Category: PL/SQL

Send SMS, MMS and Voice messages from Oracle PL/SQL

testing receipt of sms and mms

If you need to send almost any message to almost any phone from your Oracle database, and you want to use straight PL/SQL, you may want to consider using my Clicksend API.

  • SMS (Short Message Service)
  • MMS (Multimedia Message Service)
  • Text to Voice

I have released the first beta version of my Oracle PL/SQL API for Clicksend. Read the installation instructions, API reference and download the release from here:

https://jeffreykemp.github.io/clicksend-plsql-api/

Sending an SMS is as simple as adding this anywhere in your code:

begin
  clicksend_pkg.send_sms
    (p_sender  => 'TheDatabase'
    ,p_mobile  => '+61411111111'
    ,p_message => 'G''day, this is your database!'
    );
  clicksend_pkg.push_queue;
  commit;
end;

All you need to do is signup for a Clicksend account. You’ll only be charged for messages actually sent, but they do require you to pay in advance – e.g. $20 gets you about 300 messages (Australian numbers). You can get test settings so that you can try it out for free.

I’ve been using Clicksend for years now, and have been satisfied with their service and the speed and reliability of getting messages to people’s mobiles. When I encountered any issues, a chat with their support quickly resolved them, and they were quick to offer free credits when things weren’t working out as expected.

If you want to send a photo to someone’s phone via MMS (although I’m not sure what the use-case for this might be), you need to first upload the image somewhere online, because the API only accepts a URL. In my case, I would use the Amazon S3 API from the Alexandria PL/SQL Library, then pass the generated URL to the clicksend API. There is a file upload feature that ClickSend provides, I plan to add an API call to take advantage of this which will make this seamless – and provide some file conversion capabilities as well.

begin
  clicksend_pkg.send_mms
    (p_sender  => 'TheDatabase'
    ,p_mobile  => '+61411111111'
    ,p_subject => 'G''Day!'
    ,p_message => 'This is an MMS from your database!'
    ,p_media_file_url =>
'https://s3-ap-southeast-2.amazonaws.com/jk64/jk64logo.jpg'
    );
  clicksend_pkg.push_queue;
  commit;
end;

You can send a voice message to someone (e.g. if they don’t have a mobile phone) using the Text to Voice API.

begin
  clicksend_pkg.send_voice
    (p_phone_no     => '+61411111111'
    ,p_message      => 'Hello. This message was sent from your database. '
                    || 'Have a nice day.'
    ,p_voice_lang   => 'en-gb' -- British English
    ,p_voice_gender => 'male'
    ,p_schedule_dt  => sysdate + interval '2' minute
    );
  clicksend_pkg.push_queue;
  commit;
end;

You have to tell the API what language the message is in. For a number of languages, you can specify the accent/dialect (e.g. American English, British English, or Aussie) and gender (male or female). You can see the full list here.

All calls to the send_sms, send_mms and send_voice procedures use Oracle AQ to make the messages transactional. It’s up to you to either COMMIT or ROLLBACK, which determines whether the message is actually sent or not. All messages go into a single queue.

You can have a message be scheduled at a particular point in time by setting the p_schedule_dt parameter.

The default installation creates a job that runs every 5 minutes to push the queue. You can also call push_queue directly in your code after calling a send_xxx procedure. This creates a job to push the queue as well, so it won’t interfere with your transaction.

All messages get logged in a table, clicksend_msg_log. The log includes a column clicksend_cost which allows you to monitor your costs. To check your account balance, call get_credit_balance.

Please try it out if you can and let me know of any issues or suggestions for improvement.

Link: https://jeffreykemp.github.io/clicksend-plsql-api/

Email made Easier

an e-mail letter that has a @ sign on itSending emails from the Oracle database can be both simply deceptively braindead easy, and confoundingly perplexingly awful at the same time. Easy, because all you have to do is call one of the supplied mail packages to send an email:

UTL_MAIL.send
  (sender     => 'sender@host.com'
  ,recipients => 'recipient@example.com'
  ,subject    => 'Test Subject'
  ,message    => 'Test Message');
APEX_MAIL.send
  (p_from => 'sender@host.com'
  ,p_to   => 'recipient@example.com'
  ,p_subj => 'Test Subject'
  ,p_body => 'Test Message');

If you want more control over your emails you can use UTL_SMTP instead; this is what I’ve been using for the past few years because I like feeling in control (doesn’t everyone?). This is the package that APEX_MAIL is built on top of.

If you just don’t trust these high-level abstractions you can use UTL_TCP and interact directly with the mail server. I don’t know, maybe your mail server does some weird stuff that isn’t supported by the standard packages.

If you want to send attachments, you can build this yourself in UTL_SMTP or UTL_TCP, but it’s easier with APEX_MAIL which can send BLOBs. UTL_MAIL can send attachments but only up to 32K in size (half that for binary files which become base64 encoded).

Let’s make up a checklist of features supported out of the box (i.e. without requiring you to write non-trivial code) and see how they stack up:

APEX_MAIL UTL_MAIL UTL_SMTP UTL_TCP
Attachments Yes Yes (<32K) No* No*
Asynchronous Yes No No No
Rate limited Yes No No No
Anti-Spam No* No* No* No*
SSL/TLS Yes No No* No*
Authentication Yes No No* No*

Features marked “No*”: these are not natively supported by the API, but generic API routines for sending arbitrary data (including RAW) can be used to build these features, if you’re really keen or you can google the code to copy-and-paste.

(Note: of course, you can add the Asynchronous and Rate limiting features to any of the UTL_* packages by writing your own code.)

Asynchronous

Calls to the API to send an email do not attempt to connect to the mail server in the same session, but record the email to be sent soon after in a separate session.

This provides two benefits:

  1. It allows emails to be transactional – if the calling transaction is rolled back, the email will not be sent; and
  2. It ensures the client process doesn’t have to wait until the mail server responds, which might be slow in times of peak load.

Anti-Spam

Sending an email within an organisation is easy; internal mail servers don’t usually filter out internal emails as spam. Sending an email across the internet at large is fraught with difficulties, which can rear their ugly heads months or years after going live. One day your server tries to send 100 emails to the same recipient in error, and all of a sudden your IP is blocked as a spammer and NO emails get sent, with no warning.

For the last two years I’ve been battling this problem, because my site allows my clients to broadcast messages to their customers and partners via email and SMS. The SMS side worked fine, but emails frequently went AWOL and occasionally the whole site would get spam blocked. Most emails to hotmail went into a black hole and I was always having to apologise to anyone complaining about not getting their emails – “You’re not using a hotmail address by any chance? ah, that’s the problem then – sorry about that. Do you have any other email address we can use?”

I added some rate-limiting code to ensure that my server trickled the emails out. My server was sending about 2,000 to 3,000 per month, but sometimes these were sent in short spikes rather than spread out over the month. My rate-limiting meant a broadcast to 200 people could take several hours to complete, which didn’t seem to bother anyone; and this stopped the “too many emails sent within the same hour” errors from the mail server (I was using my ISP’s mail server).

I managed to improve the situation a little by implementing SPF (Sender Policy Framework). But still, lots of emails went missing, or at least directly into people’s spam folders.

I looked into DKIM as well, but after a few hours reading I threw that into the “too hard basket”. I decided that I’d much prefer to outsource all this worry and frustration to someone with more expertise and experience.

Searching for an Email Gateway

I’ve been hosting my site on Amazon EC2 for a long time now with great results and low cost, and I’ve also been using Amazon S3 for hosting large files and user-uploaded content. Amazon also provides an Email Gateway solution called SES which seemed like a logical next step. This service gives 62,000 messages per month for free (when sent from an EC2 instance) and you just get charged small amounts for the data transfer (something like 12c per GB).

I started trying to build a PL/SQL API to Amazon SES but got stuck trying to authenticate using Amazon’s complicated scheme. Just to make life interesting they use a different encryption algorithm for SES than they do for S3 (for which I already had code from the Alexandria PL/SQL library). It was difficult because their examples all assumed you’ve installed the Amazon SDK.

It always rejected anything I sent, and gave no clues as to what I might be doing wrong. In the end I decided that what I was doing wrong was trying to work this low-level stuff out myself instead of reusing a solution that someone else has already worked out. A good developer is a lazy developer, so they say. So I decided to see what other email gateways are out there.

I looked at a few, but their costs were prohibitive for my teeny tiny business as they assumed I am a big marketing company sending 100,000s of emails per month and would be happy to pay $100’s in monthly subscriptions. I wanted a low-cost, pay-per-use transactional email service that would take care of the DKIM mail signing for me.

Mailgun

In the end, I stumbled upon Mailgun, a service provided by Rackspace. Their service takes care of the DKIM signing for me, do automated rate limiting (with dynamic ramp up and ramp down), it includes 10,000 free emails per month, and extra emails are charged at very low amounts per email with no monthly subscription requirement.

Other benefits I noticed was that it allows my server to send emails by two methods: (1) RESTful API and (2) SMTP. The SMTP interface meant that I was very quickly able to use the service simply by pointing my existing Apex mail settings and my custom UTL_SMTP solution directly to the Mailgun SMTP endpoint, and it worked out of the box. Immediately virtually all our emails were getting sent, even to hotmail addresses. I was able to remove my rate limiting code. Other bonuses were that I now had much better visibility of failed emails – the Mailgun online interface provides access to a detailed log including bounces, spam blocks and other problems. So far I’ve been using it for a few weeks, and of 2,410 emails attempted, 98.55% were delivered, and 1.45% dropped. The emails that were dropped were mainly due to incorrect email addresses in my system, deliberately “bad” test emails I’ve tried, or problems on the target mail servers. One email was blocked by someone’s server which was running SpamAssassin. So overall I’ve been blown away by how well this is running.

Once I had my immediate problem solved, I decided to have a closer look at the RESTful API. This provides a few intriguing features not supported by the SMTP interface, such as sending an email to multiple recipients with substitution strings in the message, and each recipient only sees their own name in the “To” field. My previous solution for this involved sending many emails; the API means that I can send the request to Mailgun just once, and Mailgun will send out all the individual emails.

Another little bonus is that Mailgun’s API also includes a souped-up email address validator. This validator doesn’t just check email addresses according to basic email address formatting, it also checks the MX records on the target domain to determine whether it’s likely to accept emails. For some domains (such as gmail.com and yahoo.com) I noticed that it even does some level of checking of the user name portion of the email address. It’s still not absolutely perfect, but it’s better than other email validation routines I’ve seen.

Note: Mailgun supports maximum message size of 25MB.

Email Validation Plugin

Mailgun also provide a jQuery plugin for their email address validator which means you can validate user-entered email addresses on the client before they even hit your server. To take advantage of this in Oracle Apex I created the Mailgun Email Validator Dynamic Plugin that you can use and adapt if you want.

PL/SQL API

If you follow me on twitter you are probably already aware that I’ve started building a PL/SQL API to make the Mailgun RESTful API accessible to Oracle developers. You can try it out for yourself by downloading from here if you want. The WIKI on Github has detailed installation instructions (it’s a little involved) and an API reference.

The API supports the following Mailgun features:

  • Email validation – does the same thing as the jQuery-based plugin, but on the server
  • Send email
    • Attachments (CLOB or BLOB)
    • Inline images
    • Mailgun tags
    • Custom mail headers
  • Query Mailgun logs – bounces, unsubscribes, spam complaints

e.g.

MAILGUN_PKG.send_email
  (p_from_email => 'sender@host.com'
  ,p_to_email   => 'recipient@example.com'
  ,p_subject    => 'Test Subject'
  ,p_message    => 'Test Message'
  );

The API Reference has a lot more detailed examples.

My implementation of the Send Email API so far supports the following features:

MAILGUN_PKG
Attachments Yes
Asynchronous Yes
Rate limited Yes*
Anti-Spam Yes*
SSL/TLS Yes, required
Authentication Yes

Features marked “Yes*”: these are provided by the Mailgun service by default, they are not specific to this PL/SQL API.

I’m planning to add more features to the API as-and-when I have a use for them, or if someone asks me very nicely to build them. I’ll be pleased if you fork the project from Github and I welcome your pull requests to merge improvements in. I recommend reading through the Mailgun API Documentation for feature ideas.

If you use either of these in your project, please let me know as I’d love to hear about your experience with it.

Link: Oracle PL/SQL API for Mailgun

This article was not solicited nor paid for by Mailgun. I just liked the service so I wanted to blog about it.

UPDATE 26/4/2016: release 0.4 now uses Oracle AQ to enable asynchronous calls.

UPDATE 5/11/2016: release 0.6 adds APIs for querying your Mailgun logs. Also, added a note about UTL_MAIL’s attachment size limit.

Dumb triggers? Let’s make ’em a bit smarter

Some time back, Connor rightly pointed out that triggers that modify data can get in the way when you need to do out-of-the-ordinary data maintenance, e.g. when you need to fix up a row here or re-insert a row over there. You can’t just disable the trigger or else make your users suffer down-time.

Now, the only purpose for which I use triggers is to do common things like setting audit columns and incrementing a VERSION_ID column, and in certain special cases for carefully implementing cross-row constraints; also, I use them to populate a journal table with all changes to the table. Mind you, in recent times features have been added and improved in the Oracle database (such as Flashback Query and Flashback Data Archive) to the point where I’m almost ready to stop doing this. However, there are still some minor use-cases where having a separate “journal” table can be useful. Any argument about that assertion is ruled “out of scope” for this article! :)

So, assuming we’re sticking with triggers that might change data, a solution to this problem is already built-in to the journal triggers and Table APIs (TAPI) that my PL/SQL code generator creates. This allows me to disable the trigger on any table, just for my current session without affecting any other concurrent activity – and no DDL required.

UPDATED 16/2/2016: now uses a context variable (thanks Connor for the idea)

In the trigger I have this code:

create or replace TRIGGER EMPS$TRG 
  FOR INSERT OR UPDATE OR DELETE ON EMPS 
  COMPOUND TRIGGER 
 
  BEFORE EACH ROW IS 
  BEGIN 
    IF SYS_CONTEXT('SAMPLE_CTX','EMPS$TRG') IS NULL THEN 
      ...etc... 
    END IF; 
  END BEFORE EACH ROW; 
 
  AFTER EACH ROW IS 
  BEGIN 
    IF SYS_CONTEXT('SAMPLE_CTX','EMPS$TRG') IS NULL THEN 
      ...etc... 
    END IF; 
  END AFTER EACH ROW; 
 
END EMPS$TRG;

The trigger takes advantage of some extra code that is generated in the Table API:

create or replace PACKAGE EMPS$TAPI AS 
/***********************************************
 Table API for emps 
 10-FEB-2016 - Generated by SAMPLE
***********************************************/ 

... 
 
-- Use these procedures to disable and re-enable the
-- journal trigger just for this session (to disable for
-- all sessions, just disable the database trigger 
-- instead). 
PROCEDURE disable_journal_trigger; 
PROCEDURE enable_journal_trigger; 
 
END EMPS$TAPI; 

The package body code is quite simple:

create or replace PACKAGE BODY EMPS$TAPI AS 
/***********************************************
 Table API for emps 
 10-FEB-2016 - Generated by SAMPLE
***********************************************/ 
 
...

-- may be used to disable and re-enable the journal trigger for this session 
PROCEDURE disable_journal_trigger IS 
BEGIN 
  log_start('disable_journal_trigger'); 
 
  SECURITY.disable_journal_trigger('EMPS$TRG');
 
  log_end;
EXCEPTION 
  WHEN OTHERS THEN 
    UTIL.log_sqlerrm; 
    RAISE; 
END disable_journal_trigger; 
 
PROCEDURE enable_journal_trigger IS 
BEGIN 
  log_start('enable_journal_trigger'); 
 
  SECURITY.enable_journal_trigger('EMPS$TRG');
 
  log_end; 
EXCEPTION 
  WHEN OTHERS THEN 
    UTIL.log_sqlerrm; 
    RAISE; 
END enable_journal_trigger; 
 
END EMPS$TAPI;

A context variable is set with the name of the trigger to disable it – the default state for a new session (i.e. the context variable not set) means the trigger is enabled.

create or replace PACKAGE BODY SECURITY AS

...

PROCEDURE disable_journal_trigger
  (trigger_name IN VARCHAR2
  ,client_id    IN VARCHAR2 := NULL) IS
BEGIN
  -- set the context to any non-null value
  DBMS_SESSION.set_context 
    (namespace => 'SAMPLE_CTX'
    ,attribute => trigger_name
    ,value     => 'DISABLED'
    ,client_id => NVL(client_id, SYS_CONTEXT('USERENV','CLIENT_IDENTIFIER')));
END disable_journal_trigger;

PROCEDURE enable_journal_trigger
  (trigger_name IN VARCHAR2
  ,client_id    IN VARCHAR2 := NULL) IS
BEGIN
  -- clear the context
  DBMS_SESSION.clear_context 
    (namespace => 'SAMPLE_CTX'
    ,attribute => trigger_name
    ,client_id => NVL(client_id, SYS_CONTEXT('USERENV','CLIENT_IDENTIFIER')));
END enable_journal_trigger;

END SECURITY;

So now, to run some data maintenance, I can simply call the TAPI to disable, then re-enable, the trigger:

BEGIN EMPS$TAPI.disable_journal_trigger; END;
/

... do the data maintenance...

BEGIN EMPS$TAPI.enable_journal_trigger; END;
/

Unless the data maintenance is doing something very unusual, this script should be safe to run while the system is still up and running for users.

Also, it would be a trivial exercise to write a routine which disables or enables all the journal triggers at once.

The point of this, of course, is that you should be able to do all this sort of thing without writing a lot of code for each table in your schema – solve it for one table, and then generate the code for all your tables.

Source code/download: https://bitbucket.org/jk64/jk64-sample-apex-tapi

TAPI Generator MkII

The last few weeks I’ve made quite a few improvements to my TAPI generator which I thought I’d share. I’ve also added an Apex API generator which generates code suitable for interfacing between simple Apex applications and my TAPIs. This reduces the volume of PL/SQL required within Apex to a bare minimum.

  • Templates are now defined in a package spec, so they are easier to edit in a tool with syntax highlighting (more or less)
  • Most dynamic code generation is defined within the template using a simple syntax
  • Makes inferences from schema metadata to generate code, including some guesses based on object and column naming conventions.
  • Ability to insert table-specific code into the template so that it is retained after re-generating the TAPI.
  • As much as possible, allow generated code to follow my preferred code formatting rules as possible.
  • The Table API (“TAPI”) package defines two record types; one (rowtype) is based on the table, the other (rvtype) uses mostly VARCHAR2(4000) columns in order to hold a pre-validated record.

Assumptions

My generator makes the following assumptions:

  • All tables and columns are named non-case-sensitive, i.e. no double-quote delimiters required.
  • (APEX API) All columns are max 26 chars long (in order to accommodate the Apex “P99_…” naming convention)
  • (APEX API) Table has no more than 1 CLOB, 1 BLOB and 1 XMLTYPE column (in order to support conversion to/from Apex collections)

If any of the above do not hold true, the TAPI will probably need to be manually adjusted to work. All TAPIs generated should be reviewed prior to use anyway.

Example

For example, given the following schema:

CREATE TABLE emps
  (emp_id       NUMBER NOT NULL
  ,name         VARCHAR2(100 CHAR) NOT NULL
  ,emp_type     VARCHAR2(20 CHAR) DEFAULT 'SALARIED' NOT NULL
  ,start_date   DATE NOT NULL
  ,end_date     DATE
  ,dummy_ts     TIMESTAMP(6)
  ,dummy_tsz    TIMESTAMP(6) WITH TIME ZONE
  ,life_history CLOB
  ,CONSTRAINT emps_pk PRIMARY KEY ( emp_id )
  ,CONSTRAINT emps_name_uk UNIQUE ( name )
  ,CONSTRAINT emp_type_ck
     CHECK ( emp_type IN ('SALARIED','CONTRACTOR')
  );
CREATE SEQUENCE emp_id_seq;

I can run this:

BEGIN GENERATE.tapi('emps'); END;
/

This generates the following package (I’ve removed large portions, the full version is linked below):

create or replace PACKAGE EMPS$TAPI AS 
/**********************************************************
 Table API for emps 
 10-FEB-2016 - Generated by SAMPLE
**********************************************************/ 
 
SUBTYPE rowtype IS emps%ROWTYPE; 
 
TYPE arraytype IS TABLE OF rowtype INDEX BY BINARY_INTEGER; 
 
TYPE rvtype IS RECORD 
  (emp_id       emps.emp_id%TYPE 
  ,name         VARCHAR2(4000) 
  ,emp_type     VARCHAR2(4000) 
  ,start_date   VARCHAR2(4000) 
  ,end_date     VARCHAR2(4000) 
  ,dummy_ts     VARCHAR2(4000) 
  ,dummy_tsz    VARCHAR2(4000) 
  ,life_history emps.life_history%TYPE 
  ,version_id   emps.version_id%TYPE 
  ); 
 
TYPE rvarraytype IS TABLE OF rvtype INDEX BY BINARY_INTEGER; 
 
-- validate the row (returns an error message if invalid) 
FUNCTION val (rv IN rvtype) RETURN VARCHAR2; 
 
-- insert a row 
FUNCTION ins (rv IN rvtype) RETURN rowtype; 
 
-- insert multiple rows, array may be sparse
-- returns no. records inserted 
FUNCTION bulk_ins (arr IN rvarraytype) RETURN NUMBER; 

$if false $then/*need to grant DBMS_CRYPTO*/ 
-- generate a hash for the record 
FUNCTION hash (r IN rowtype) RETURN VARCHAR2; 
$end

...
 
END EMPS$TAPI;
create or replace PACKAGE BODY EMPS$TAPI AS 
/**********************************************************
 Table API for emps 
 10-FEB-2016 - Generated by SAMPLE
**********************************************************/ 
 
FUNCTION val (rv IN rvtype) RETURN VARCHAR2 IS 
  -- Validates the record but without reference to any other rows or tables 
  -- (i.e. avoid any queries in here). 
  -- Unique and referential integrity should be validated via suitable db 
  -- constraints (violations will be raised when the ins/upd/del is attempted). 
  -- Complex cross-record validations should usually be performed by a XAPI 
  -- prior to the call to the TAPI. 
BEGIN 
  log_start('val'); 
 
  UTIL.val_not_null (val => rv.name, column_name => 'NAME'); 
  UTIL.val_not_null (val => rv.emp_type, column_name => 'EMP_TYPE'); 
  UTIL.val_not_null (val => rv.start_date, column_name => 'START_DATE'); 
   
  UTIL.val_max_len (val => rv.name, len => 100, column_name => 'NAME'); 
  UTIL.val_max_len (val => rv.emp_type, len => 20, column_name => 'EMP_TYPE'); 
  UTIL.val_date (val => rv.start_date, column_name => 'START_DATE'); 
  UTIL.val_date (val => rv.end_date, column_name => 'END_DATE'); 
  UTIL.val_timestamp (val => rv.dummy_ts, column_name => 'DUMMY_TS'); 
  UTIL.val_timestamp_tz (val => rv.dummy_tsz, column_name => 'DUMMY_TSZ'); 
   
   
  --TODO: add more validations if necessary 
 
  log_end; 
  RETURN UTIL.first_error; 
EXCEPTION 
  WHEN UTIL.application_error THEN 
    log_end('application_error'); 
    RAISE; 
  WHEN OTHERS THEN 
    UTIL.log_sqlerrm; 
    RAISE; 
END val; 
 
FUNCTION ins (rv IN rvtype) RETURN rowtype IS 
  r         rowtype; 
  error_msg VARCHAR2(32767); 
BEGIN 
  log_start('ins'); 
 
  error_msg := val (rv => rv); 
 
  IF error_msg IS NOT NULL THEN 
    raise_error(error_msg); 
  END IF; 
 
  INSERT INTO emps 
        (emp_id 
        ,name 
        ,emp_type 
        ,start_date 
        ,end_date 
        ,dummy_ts 
        ,dummy_tsz 
        ,life_history) 
  VALUES(emp_id_seq.NEXTVAL 
        ,rv.name 
        ,rv.emp_type 
        ,UTIL.date_val(rv.start_date) 
        ,UTIL.date_val(rv.end_date) 
        ,UTIL.timestamp_val(rv.dummy_ts) 
        ,UTIL.timestamp_tz_val(rv.dummy_tsz) 
        ,rv.life_history) 
  RETURNING 
         emp_id 
        ,name 
        ,emp_type 
        ,start_date 
        ,end_date 
        ,dummy_ts 
        ,dummy_tsz 
        ,life_history 
        ,created_by 
        ,created_dt 
        ,last_updated_by 
        ,last_updated_dt 
        ,version_id 
  INTO   r.emp_id 
        ,r.name 
        ,r.emp_type 
        ,r.start_date 
        ,r.end_date 
        ,r.dummy_ts 
        ,r.dummy_tsz 
        ,r.life_history 
        ,r.created_by 
        ,r.created_dt 
        ,r.last_updated_by 
        ,r.last_updated_dt 
        ,r.version_id; 
 
  msg('INSERT emps: ' || SQL%ROWCOUNT); 
 
  log_end; 
  RETURN r; 
EXCEPTION 
  WHEN DUP_VAL_ON_INDEX THEN 
    UTIL.raise_dup_val_on_index; 
  WHEN UTIL.application_error THEN 
    log_end('application_error'); 
    RAISE; 
  WHEN OTHERS THEN 
    UTIL.log_sqlerrm; 
    RAISE; 
END ins; 
 
FUNCTION bulk_ins (arr IN rvarraytype) RETURN NUMBER IS 
  rowcount NUMBER; 
BEGIN 
  log_start('bulk_ins'); 
 
  bulk_val(arr); 
 
  FORALL i IN INDICES OF arr 
    INSERT INTO emps 
           (emp_id 
           ,name 
           ,emp_type 
           ,start_date 
           ,end_date 
           ,dummy_ts 
           ,dummy_tsz 
           ,life_history) 
    VALUES (emp_id_seq.NEXTVAL 
           ,arr(i).name 
           ,arr(i).emp_type 
           ,UTIL.date_val(arr(i).start_date) 
           ,UTIL.date_val(arr(i).end_date) 
           ,UTIL.timestamp_val(arr(i).dummy_ts) 
           ,UTIL.timestamp_tz_val(arr(i).dummy_tsz) 
           ,arr(i).life_history); 
 
  rowcount := SQL%ROWCOUNT; 
 
  msg('INSERT emps: ' || rowcount); 
 
  log_end('rowcount=' || rowcount); 
  RETURN rowcount; 
EXCEPTION 
  WHEN DUP_VAL_ON_INDEX THEN 
    UTIL.raise_dup_val_on_index; 
  WHEN UTIL.application_error THEN 
    log_end('application_error'); 
    RAISE; 
  WHEN OTHERS THEN 
    UTIL.log_sqlerrm; 
    RAISE; 
END bulk_ins; 

$if false $then/*need to grant DBMS_CRYPTO*/ 
FUNCTION hash (r IN rowtype) RETURN VARCHAR2 IS 
  sep    CONSTANT VARCHAR2(1) := '|'; 
  digest CLOB; 
  ret    RAW(2000); 
BEGIN 
  log_start('hash'); 
 
  digest := digest || sep || r.emp_id; 
  digest := digest || sep || r.name; 
  digest := digest || sep || r.emp_type; 
  digest := digest || sep || TO_CHAR(r.start_date, UTIL.DATE_FORMAT); 
  digest := digest || sep || TO_CHAR(r.end_date, UTIL.DATE_FORMAT); 
  digest := digest || sep || TO_CHAR(r.dummy_ts, UTIL.TIMESTAMP_FORMAT); 
  digest := digest || sep || TO_CHAR(r.dummy_tsz, UTIL.TIMESTAMP_TZ_FORMAT); 
 
  ret := DBMS_CRYPTO.hash(digest, DBMS_CRYPTO.hash_sh1); 
 
  log_end(ret); 
  RETURN ret; 
EXCEPTION 
  WHEN UTIL.application_error THEN 
    log_end('application_error'); 
    RAISE; 
  WHEN OTHERS THEN 
    UTIL.log_sqlerrm; 
    RAISE; 
END hash; 
$end

...

END EMPS$TAPI;

Example Template

The following is a template which provides the source used to generate the above TAPI. The syntax may look very strange, but if you read on you can read my explanation of the syntax below. My goal was not to invent an all-singing all-dancing general-purpose syntax for code generation – but to have “just enough” expressive power to generate the kind of code I require.

create or replace PACKAGE TEMPLATES AS
$if false $then
<%TEMPLATE TAPI_PACKAGE_SPEC>
CREATE OR REPLACE PACKAGE #TAPI# AS
/**********************************************************
 Table API for #table#
 #SYSDATE# - Generated by #USER#
**********************************************************/
<%IF EVENTS>
/*Repeat Types*/
DAILY    CONSTANT VARCHAR2(100) := 'DAILY';
WEEKLY   CONSTANT VARCHAR2(100) := 'WEEKLY';
MONTHLY  CONSTANT VARCHAR2(100) := 'MONTHLY';
ANNUALLY CONSTANT VARCHAR2(100) := 'ANNUALLY';
<%END IF>
SUBTYPE rowtype IS #table#%ROWTYPE;

TYPE arraytype IS TABLE OF rowtype INDEX BY BINARY_INTEGER;

TYPE rvtype IS RECORD
  (<%COLUMNS EXCLUDING AUDIT INCLUDING ROWID,EVENTS.REPEAT_IND>
   #col#--- VARCHAR2(4000)~
   #col#--- #table#.#col#%TYPE{ID}~
   #col#--- #table#.#col#%TYPE{LOB}~
   #col#--- VARCHAR2(20){ROWID}~
   #col#--- VARCHAR2(1){EVENTS.REPEAT_IND}~
  ,<%END>
  );

TYPE rvarraytype IS TABLE OF rvtype INDEX BY BINARY_INTEGER;

-- validate the row (returns an error message if invalid)
FUNCTION val (rv IN rvtype) RETURN VARCHAR2;

-- insert a row
FUNCTION ins (rv IN rvtype) RETURN rowtype;

-- insert multiple rows, array may be sparse; returns no. records inserted
FUNCTION bulk_ins (arr IN rvarraytype) RETURN NUMBER;

...

<%IF DBMS_CRYPTO><%ELSE>$if false $then/*need to grant DBMS_CRYPTO*/<%END IF>
-- generate a hash for the record
FUNCTION hash (r IN rowtype) RETURN VARCHAR2;
<%IF DBMS_CRYPTO><%ELSE>$end<%END IF>

END #TAPI#;
<%END TEMPLATE>

<%TEMPLATE TAPI_PACKAGE_BODY>
CREATE OR REPLACE PACKAGE BODY #TAPI# AS
/**********************************************************
 Table API for #table#
 #SYSDATE# - Generated by #USER#
**********************************************************/

FUNCTION val (rv IN rvtype) RETURN VARCHAR2 IS
  -- Validates the record but without reference to any other rows or tables
  -- (i.e. avoid any queries in here).
  -- Unique and referential integrity should be validated via suitable db
  -- constraints (violations will be raised when the ins/upd/del is attempted).
  -- Complex cross-record validations should usually be performed by a XAPI
  -- prior to the call to the TAPI.
BEGIN
  log_start('val');

  <%COLUMNS EXCLUDING GENERATED,SURROGATE_KEY,NULLABLE>
  UTIL.val_not_null (val => rv.#col#, column_name => '#COL#');~
  <%END>
  <%IF EVENTS>
  IF rv.repeat_ind = 'Y' THEN
    UTIL.val_not_null (val => rv.repeat, column_name => 'REPEAT');
    UTIL.val_not_null (val => rv.repeat_interval, column_name => 'REPEAT_INTERVAL');
  END IF;
  <%END IF>
  <%COLUMNS EXCLUDING GENERATED,SURROGATE_KEY,LOBS INCLUDING EVENTS.REPEAT_IND>
  UTIL.val_ind (val => rv.#col#, column_name => '#COL#');{IND}~
  UTIL.val_yn (val => rv.#col#, column_name => '#COL#');{YN}~
  UTIL.val_max_len (val => rv.#col#, len => #MAXLEN#, column_name => '#COL#');{VARCHAR2}~
  UTIL.val_numeric (val => rv.#col#, column_name => '#COL#');{NUMBER}~
  UTIL.val_date (val => rv.#col#, column_name => '#COL#');{DATE}~
  UTIL.val_datetime (val => rv.#col#, column_name => '#COL#');{DATETIME}~
  UTIL.val_timestamp (val => rv.#col#, column_name => '#COL#');{TIMESTAMP}~
  UTIL.val_timestamp_tz (val => rv.#col#, column_name => '#COL#');{TIMESTAMP_TZ}~
  UTIL.val_integer (val => rv.#col#, range_low => 1, column_name => '#COL#');{EVENTS.REPEAT_INTERVAL}~
  UTIL.val_domain
    (val          => rv.#col#
    ,valid_values => t_str_array(DAILY, WEEKLY, MONTHLY, ANNUALLY)
    ,column_name  => '#COL#');{EVENTS.REPEAT}~
  ~
  <%END>
  <%IF EVENTS>
  UTIL.val_datetime_range
    (start_dt => rv.start_dt
    ,end_dt   => rv.end_dt
    ,label    => 'Event Date/Time Range');
  <%END IF>
  <%IF EVENT_TYPES>
  UTIL.val_cond
    (cond        => rv.event_type = UPPER(rv.event_type)
    ,msg         => 'Event Type Code must be all uppercase'
    ,column_name => 'EVENT_TYPE');
  UTIL.val_cond
    (cond        => rv.event_type = TRANSLATE(rv.event_type,'X -:','X___')
    ,msg         => 'Event Type Code cannot include spaces, dashes (-) or colons (:)'
    ,column_name => 'EVENT_TYPE');
  UTIL.val_date_range
    (start_date => rv.start_date
    ,end_date   => rv.end_date
    ,label      => 'Event Types Date Range');
  <%END IF>
  --TODO: add more validations if necessary

  log_end;
  RETURN UTIL.first_error;
EXCEPTION
  WHEN UTIL.application_error THEN
    log_end('application_error');
    RAISE;
  WHEN OTHERS THEN
    UTIL.log_sqlerrm;
    RAISE;
END val;

FUNCTION ins (rv IN rvtype) RETURN rowtype IS
  r         rowtype;
  error_msg VARCHAR2(32767);
BEGIN
  log_start('ins');

  error_msg := val (rv => rv);

  IF error_msg IS NOT NULL THEN
    raise_error(error_msg);
  END IF;

  INSERT INTO #table#
        (<%COLUMNS EXCLUDING GENERATED>
        #col#~
        ,<%END>)
  VALUES(<%COLUMNS EXCLUDING GENERATED>
         #seq#.NEXTVAL{SURROGATE_KEY}~
         rv.#col#~
         UTIL.num_val(rv.#col#){NUMBER}~
         UTIL.date_val(rv.#col#){DATE}~
         UTIL.datetime_val(rv.#col#){DATETIME}~
         UTIL.timestamp_val(rv.#col#){TIMESTAMP}~
         UTIL.timestamp_tz_val(rv.#col#){TIMESTAMP_TZ}~
        ,<%END>)
  RETURNING
         <%COLUMNS INCLUDING VIRTUAL>
         #col#~
        ,<%END>
  INTO   <%COLUMNS INCLUDING VIRTUAL>
         r.#col#~
        ,<%END>;

  msg('INSERT #table#: ' || SQL%ROWCOUNT);

  log_end;
  RETURN r;
EXCEPTION
  WHEN DUP_VAL_ON_INDEX THEN
    UTIL.raise_dup_val_on_index;
  WHEN UTIL.application_error THEN
    log_end('application_error');
    RAISE;
  WHEN OTHERS THEN
    UTIL.log_sqlerrm;
    RAISE;
END ins;

FUNCTION bulk_ins (arr IN rvarraytype) RETURN NUMBER IS
  rowcount NUMBER;
BEGIN
  log_start('bulk_ins');

  bulk_val(arr);

  FORALL i IN INDICES OF arr
    INSERT INTO #table#
           (<%COLUMNS EXCLUDING GENERATED>
            #col#~
           ,<%END>)
    VALUES (<%COLUMNS EXCLUDING GENERATED>
            #seq#.NEXTVAL{SURROGATE_KEY}~
            arr(i).#col#~
            UTIL.num_val(arr(i).#col#){NUMBER}~
            UTIL.date_val(arr(i).#col#){DATE}~
            UTIL.datetime_val(arr(i).#col#){DATETIME}~
            UTIL.timestamp_val(arr(i).#col#){TIMESTAMP}~
            UTIL.timestamp_tz_val(arr(i).#col#){TIMESTAMP_TZ}~
           ,<%END>);

  rowcount := SQL%ROWCOUNT;

  msg('INSERT #table#: ' || rowcount);

  log_end('rowcount=' || rowcount);
  RETURN rowcount;
EXCEPTION
  WHEN DUP_VAL_ON_INDEX THEN
    UTIL.raise_dup_val_on_index;
  WHEN UTIL.application_error THEN
    log_end('application_error');
    RAISE;
  WHEN OTHERS THEN
    UTIL.log_sqlerrm;
    RAISE;
END bulk_ins;

<%IF DBMS_CRYPTO><%ELSE>$if false $then/*need to grant DBMS_CRYPTO*/<%END IF>
FUNCTION hash (r IN rowtype) RETURN VARCHAR2 IS
  sep    CONSTANT VARCHAR2(1) := '|';
  digest CLOB;
  ret    RAW(2000);
BEGIN
  log_start('hash');

  <%COLUMNS EXCLUDING GENERATED,LOBS>
  digest := digest || sep || r.#col#;~
  digest := digest || sep || TO_CHAR(r.#col#, UTIL.DATE_FORMAT);{DATE}~
  digest := digest || sep || TO_CHAR(r.#col#, UTIL.DATETIME_FORMAT);{DATETIME}~
  digest := digest || sep || TO_CHAR(r.#col#, UTIL.TIMESTAMP_FORMAT);{TIMESTAMP}~
  digest := digest || sep || TO_CHAR(r.#col#, UTIL.TIMESTAMP_TZ_FORMAT);{TIMESTAMP_TZ}~
  <%END>

  ret := DBMS_CRYPTO.hash(digest, DBMS_CRYPTO.hash_sh1);

  log_end(ret);
  RETURN ret;
EXCEPTION
  WHEN UTIL.application_error THEN
    log_end('application_error');
    RAISE;
  WHEN OTHERS THEN
    UTIL.log_sqlerrm;
    RAISE;
END hash;
<%IF DBMS_CRYPTO><%ELSE>$end<%END IF>

END #TAPI#;
<%END TEMPLATE>

$end
END TEMPLATES;

Template Syntax

You may be wondering what all the <%bla> and #bla# tags mean. These are the controlling elements for my code generator.

All template code is embedded within $if false $then ... $end so that the template package spec can be compiled without error in the schema, while still allowing most syntax highlighters to make the template easy to read and edit. This source is then read by the generator from the TEMPLATES database package.

Each template within the TEMPLATES package is delineated by the following structural codes, each of which must appear at the start of a line:

<%TEMPLATE template_name>
...
<%END TEMPLATE>

Anything in the TEMPLATES package not within these structural elements is ignored by the generator.

Some simple placeholders are supported anywhere in a template:

  • #SYSDATE# – Today’s date in DD-MON-YYYY format
  • #TABLE# – Table name in uppercase
  • #table# – Table name in lowercase
  • #USER# – User name who executed the procedure
  • #Entity# – User-friendly name based on table name, singular (e.g. EVENTS -> Event)
  • #Entities# – User-friendly name based on table name
  • #TAPI# – Table API package name
  • #APEXAPI# – Apex API package name
  • \n – Insert a linefeed (not often required, since actual linefeeds in the template are usually retained)

These are all case-sensitive; in some cases an UPPERCASE, lowercase and Initcap version is supported for a placeholder.

Code portions that are only required in certain cases may be surrounded with the IF/ELSE/END IF structure:

<%IF condition>
   ...
<%ELSE>
   ...
<%END IF>

Currently the list of conditions are limited to LOBS (true if the table has any LOB-type columns), ROWID (true if the table does NOT have a surrogate key (i.e. a primary key matched by name to a sequence), or the name of a table (useful to have some code that is only generated for a specific table), or the name of a DBMS_xxx package (useful to have code that is only generated if the owner has been granted EXECUTE on the named DBMS_xxx package).

To negate a condition, simply leave the first part of the IF/ELSE part empty, e.g.:

<%IF LOBS><%ELSE> /*this table has no LOBS*/ <%END IF>

Code portions that need to be repeated for each column (or a subset of columns) in the table use the COLUMNS structure:

(<%COLUMNS>
 #col#--- => :#COL#~
,<%END>)

The COLUMNS structure looks very weird and might take a while to get used to, but basically it contains a list of sub-templates, delimited by tildes (~). The first sub-template (e.g. #col#--- => :#COL#) is used for each column, and the second sub-template (e.g. ,) is inserted between each column (if there is more than one column). In the above example, our emps table would result in the following generated:

(emp_id       => :EMP_ID
,name         => :NAME
,emp_type     => :EMP_TYPE
,start_date   => :START_DATE
,end_date     => :END_DATE
,dummy_ts     => :DUMMY_TS
,dummy_tsz    => :DUMMY_TSZ
,life_history => :LIFE_HISTORY)

Notice that #col# is replaced with the column name in lowercase, and #COL# is replaced with the column name in uppercase. In addition, the --- is a special code that causes the generator to insert additional spaces so that the code is aligned vertically. Notice also that the second sub-template (the separator bit with the comma) also includes a carriage return (after ~ and before ,). If we had instead used the following template:

<%COLUMNS>
#col#--- => :#COL#~,<%END>

This would have been the result:

emp_id       => :EMP_ID,name         => :NAME,emp_type     => :EMP_TYPE,start_date   => :START_DATE,end_date     => :END_DATE,dummy_ts     => :DUMMY_TS,dummy_tsz    => :DUMMY_TSZ,life_history => :LIFE_HISTORY

The generator gives you a great deal of control over which columns are included. The COLUMNS structure supports three optional clauses: INCLUDING, EXCLUDING and ONLY.

<%COLUMNS>
  (all columns in the table, EXCEPT for virtual columns)
<%END>

<%COLUMNS INCLUDING VIRTUAL>
  (all columns in the table, including virtual columns)
<%END>

<%COLUMNS EXCLUDING PK>
  (all columns except for Primary Key columns)
<%END>

<%COLUMNS EXCLUDING LOBS>
  (all columns except for LOB-type columns)
<%END>

<%COLUMNS EXCLUDING EMPS.NAME>
  (all columns - except for the specified column)
<%END>

<%COLUMNS EXCLUDING AUDIT>
  (all columns except for the audit columns such as CREATED_BY, etc.)
<%END>

<%COLUMNS ONLY PK>
  (only Primary Key columns)
<%END>

<%COLUMNS ONLY PK,NAME>
  (only Primary Key columns and columns named NAME)
<%END>

<%COLUMNS INCLUDING ROWID>
  (all columns in the table, plus the pseudocolumn ROWID)
<%END>

<%COLUMNS INCLUDING MADEUPNAME>
  (all columns in the table, plus a fake column)
<%END>

<%COLUMNS INCLUDING EMPS.MADEUPNAME>
  (all columns in the table, plus a fake column for the specified table)
<%END>

<%COLUMNS ONLY SURROGATE_KEY,VERSION_ID INCLUDING ROWID>
  (multiple criteria may be combined)
<%END>

Within a sub-template the following placeholders are recognised:

  • #COL# – column name in uppercase
  • #col# – column name in lowercase
  • #Label# – generated user-friendly label based on column name
  • #MAXLEN# – max length for a CHAR-type column
  • #DATA_DEFAULT# – column default value
  • #SEQ# – surrogate key sequence name
  • #00i# – 001, 002, 003 etc. in order of column id
  • --- – padding (inserts just enough extra spaces depending on length of column name so that code is aligned vertically)

For example, the following generates a comma-delimited list of user-friendly labels for each column in the table:

<%COLUMNS>#Label#~, <%END>
Emp, Name, Emp Type, Start, End, Dummy, Dummy, Life History

Side Note: it’s noteworthy that I have no need for a “#datatype#” placeholder; in most cases my templates will anchor to the column’s datatype anyway, so a template just needs to use #col#%TYPE.

Multiple additional sub-templates may be provided within a <%COLUMNS> structure, to be used for certain columns. These must end with a {X} indicator, where X can be a data type or column name. Other indicators are supported for special cases as well.

<%COLUMNS>
Default subtemplate                       ~
ID column                                 {ID}~
NUMBER column                             {NUMBER}~
Date/time column                          {DATETIME}~
Date column                               {DATE}~
Timestamp column                          {TIMESTAMP}~
Timestamp with time zone                  {TIMESTAMP_TZ}~
Indicator (Y or null) column              {IND}~
Yes/No (Y or N) column                    {YN}~
Any other VARCHAR2 column                 {VARCHAR2}~
Any LOB-type column (e.g. BLOB, CLOB)     {LOB}~
Any specific datatype                     {CLOB}~
Primary key matched to a sequence         {SURROGATE_KEY}~
Special case for a specific column        {TABLE.COLUMN}~
Extra code to be used if NO columns match {NONE}~
,<%END>

The “data type” for a column is usually just the data type from the schema data dictionary; however, there are some special cases where a special data type is derived from the column name:

  • ID: a NUMBER column with a name ending with _ID
  • DATETIME: a DATE column with name ending with _DT
  • IND: a VARCHAR2 column with a name ending with _IND
  • YN: a VARCHAR2 column with a name ending with _YN

Within a template it is possible to import the code from another template (e.g. to share code between multiple templates, or to facilitate a nested-IF structure) using this structure:

<%INCLUDE OTHERTEMPLATE>

This will cause the generator to find a template named OTHERTEMPLATE, evaluate it, then insert it at the given position.

This method has allowed my code generator to be quite flexible and powerful, makes it easy to add additional code to all my API packages and other generated code, and makes it easy to find and fix errors.

You can download all the source for the template and generator below. Note that a new Sample Apex application is included (f560.sql) which works in Apex 5 and uses the new Apex API. Disclaimer:This is a work in progress!

If you find it useful or you have suggestions for improvement please comment.

Source code/download: https://bitbucket.org/jk64/jk64-sample-apex-tapi

“Smart quotes” showing as “?” in emails

When some of my users were using my system to send emails, they’d often copy-and-paste their messages from their favourite word processor, but when my system sent the emails they’d have question marks dotted around, e.g.

“Why doesn’t this work?”

would get changed to

?Why doesn?t? this work??

Simple fix was to detect and replace those fancy-pants quote characters with the equivalent html entities, e.g.:

function enc_chars (m in varchar2) return varchar2 is
begin
  return replace(replace(replace(replace(m
    ,chr(14844060),'&#8220;')/*left double quote*/
    ,chr(14844061),'&#8221;')/*right double quote*/
    ,chr(96)      ,'&#8216;')/*left single quote*/
    ,chr(14844057),'&#8217;')/*right single quote*/
    ;
end enc_chars;

P.S. Stupid wordpress keeps mucking around with my code, trying to replace the html entities with the unencoded versions. In case this doesn’t work, here’s an image of what the above code is supposed to look like:
enc_chars