In building a code generator I found the need to write a number of helper methods for doing basic modifications of arrays that are indexed by integer – such as appending one array onto another, inserting, and shifting. These arrays represent an ordered sequence of strings (e.g. lines of source code).
I think these would be a useful addition to the language if they were made native – e.g. (new commands in UPPERCASE):
type str_array_type is table of varchar2(32767)
index by binary_integer;
.. (some code to fill the arrays here) ..
-- get a subset of lines
l_new := l_lines.SLICE(50, 59);
-- extend l_lines with l_new at the end:
-- shift l_lines forwards and insert l_new
-- at the beginning:
-- insert l_new into l_lines at the given index;
-- shift any existing lines at that location
l_lines.INSERT(l_new, at_idx => 21);
-- remove the given range of indices from
-- l_lines, replace with whatever is in l_new:
from_idx => 120,
to_idx => 149);
-- apply the given substitution on each line
old_val => 'foo',
new_val => 'bar');
-- shift the given range of lines by the given
-- offset (raise exception if existing data
-- would get overwritten):
from_idx => 20,
to_idx => 29,
offset => 1000);
-- shift and renumber all indices in the array
-- with the given starting index and increment:
l_lines.RENUMBER(start_idx => 10, increment => 10);
-- make the array contiguous (i.e. remove gaps):
-- loop over every line in the array that contains
-- the given string:
l_idx := l_lines.FIND_NEXT(contains => 'hello');
exit when l_idx is null;
.. do something with l_lines(l_idx) ..
l_idx := l_lines.FIND_NEXT(contains => 'hello',
from_idx => l_idx);
I’ve illustrated these with a little sample package that may be viewed here:
The plugin now supports Overlays, which allows you to add almost any arbitrary HTML or image content to particular points on the map. For example, instead of showing the default red pin, you might want to show a pretty Information card at a location. The cards are clickable as well, and you can use a dynamic action to make your app respond however you wish.
You can even show an image as a map overlay, which will be scaled automatically as the user zooms and pans the map.
The Australian Oracle User Group is hosting a series of webinars this year and on 17 February I’ll be speaking about how to add an interactive Google Map to your APEX application. If you’re using APEX and want to see how easy it can be to integrate Google Map capabilities into your application, this is for you.
My session is at 9am in Perth time (1am UTC) – which is:
One of the nice things about PL/SQL is that it implements short circuit evaluation, a performance enhancement which takes advantage of the fact that an expression using logical AND or OR does not necessarily to evaluate both operands to determine the overall result.
For an expression using AND, if the first operand is not TRUE, the overall expression cannot be TRUE; for one using OR, if the first operand is TRUE, the overall expression must be TRUE. In the case of AND, what if the first operand is Unknown? It seems to depend on how the expression is used.
In my examples below, I have an expression that looks up an array. When an array is accessed with a key that is null, it will raise an exception. If short circuit evaluation is applied, the array is never accessed so the exception is not raised.
In the first example below, the PL/SQL engine never evaluates the second expression since the first expression ('abc' = p_param) is not TRUE:
l_result boolean := false;
if 'abc' = p_param and l_arr(p_param) = 'bla' then
l_result := true;
This does not apply if the expression is being assigned to a variable. In the second example below, the exception ORA-06502: PL/SQL: numeric or value error: NULL index table key value is raised:
l_result := 'abc' = p_param and l_arr(p_param) = 'bla';
If the first expression were to result in FALSE, it runs without error. If the first expression is Unknown (NULL), the second operand must be evaluated to determine whether to assign FALSE or NULL to the result.
A workaround is to use an IF statement to make the evaluation order explicit:
l_result boolean := false;
if 'abc' = p_param then
l_result := l_arr(p_param) = 'bla';
Thanks to Connor for clearing up my understanding for this one.
8/10/2020 updated with better example code – instead of comparing to a literal null (which is never right), we compare to a variable which may or may not be null at runtime.
Need to run DBMS_MVIEW.explain_mview in APEX SQL Workshop, but don’t have the MV_CAPABILITIES_TABLE? You’ll get this error:
ORA-30377: table ORDS_PUBLIC_USER.MV_CAPABILITIES_TABLE not found
You don’t need to create this table. You could create this table by running admin/utlxmv.sql (if you have it). Instead, you can get the output in an array and do whatever you want with its contents, e.g.:
dbms_output.put_line('Explain MV '
|| a(1).mvowner || '.' || a(1).mvname);
for i in 1..a.count loop
|| ' [' || case a(i).possible
when 'T' then 'TRUE'
when 'F' then 'FALSE'
end || ']'
|| case when a(i).related_num != 0 then
' ' || a(i).related_text
|| ' (' || a(i).related_num || ')'
|| case when a(i).msgno != 0 then
' ' || a(i).msgtxt
|| ' (' || a(i).msgno || ')'
The result will be something like this:
Now, the challenge is merely how to resolve some of those “FALSEs” …
This is implemented as a radio item with a dynamic action on the Change event:
The dynamic action has the following attributes:
Note that in this case, it sets an Option – Map Type, based on the triggering element (the P28_MAP_TYPE item). The Affected Elements is required, and must refer to the map region that we want to change.
Notice anything missing? That’s right – No Code needed!
The plugin makes it easy to customise which of the default Google Map controls (buttons, etc.) are shown to the user:
Full Screen control
Map Type control
Street View Pegman control
Other options that can be set include:
Disable default UI
Maximum Zoom level
Minimum Zoom level
Restrict search to Country
In addition, the plugin allows you to restrict the map to a set of bounds, via the Restrict to Bounds or Restrict to Bounds Strict Mode actions.
Another enhancement included in this release is explicit support for the Table / View data source. This is simple to use, although not quite as flexible as the SQL Query option. Your table or view must include columns with the correct column names expected by the selected Visualisation – for example, if your Visualisation is Pins, the table or view must have columns named lat, lng, name and id. Click the Help tab on Table Name for more details, or review the WIKI (https://github.com/jeffreykemp/jk64-plugin-reportmap/wiki/SQL-Query-Examples).
NOTE: the plugin supports APEX 18.2 and later. It is no longer planned to include backports for older versions of APEX.
A big thanks to many APEX developers around the world who have installed and used the map plugin over the years. Your suggestions, questions and bug reports have contributed a great deal to improving the plugin.
Sometimes we can too quickly say “No” when we should take a moment to think about whether we can actually say “Yes”. This was one of those times for me.
We had just gone live with a fairly big system move + upgrade – a suite of APEX applications shifted from one database instance running APEX 5 to another instance running version 19.1. The migration went smoothly. After the new instance was released to the business to do some final shakedown testing, they noticed one problem:
“All our saved reports are gone.”
Oops. We had built the new instance by simply importing each application from source control; since these scripts don’t include the Saved Report formats that users had customised in many of the Interactive Reports in prod, they didn’t get migrated to the new database.
When they asked if we can transfer the saved reports across, I initially replied, “Sorry, we can’t” – thinking that redoing the migration from scratch with a full export from the old database, followed by re-doing all the app changes, was going to take too much time and effort.
A minute later, I sent another email. “Hold that thought – there is a way.” I’d forgotten that my script for exporting the applications uses an APEX API with some parameters that until now I’d rarely used, but which would solve our problem. My script included this:
Version 1.2 of the ReportMap Google Map plugin has been released today. While the rest of you have been idling away under Covid-19 restrictions, I’ve been happy as a clam working on some exciting enhancements to the plugin.
Included in this release are the following new features:
New visualisation: Spidifier
Show turn-by-turn Directions
Load large data sets in batches
Show spinner while data is loading
A bug when the new Friendly URLs feature of Oracle APEX 20.1 is used with the Clustering visualisation has also been fixed in this release.
The full list of enhancements and bugfixes, with links to the issues register, may be viewed here.
If you have a map that needs to show a lot of pins, especially ones that are close together, the plugin previously had the option of Clustering them at high zoom levels. The user could click on a cluster to zoom in enough to show the individual pins. One weakness of this approach is that if one or more pins are almost (or exactly) overlapping, the cluster never “unclusters” – the user cannot zoom in far enough to get the pins to show individually.
This release provides another Visualisation option, Spiderfier. This uses the OverlappingMarkerSpiderfier to control how pins react when clicked. When the user clicks a pin that is close or overlapping with other pins, it shifts the pins in that area into a ring, or a spiral (depending on how many pins are there) with lines pointing back to their original location. It also colours them blue to indicate they’ve been “spiderfied”. The user can then hover and click each marker separately.
If the user zooms in, the Spiderfier automatically returns all the pins to their original location.
The WIKI has been augmented with a handy guide to Map Icons. The plugin has long supported the ability to specify custom images for the marker icons. This release gives a whole lot more control over the markers to the developer:
If all the icons in the query are being loaded from the same location, you can now set the iconBasePath option once and just have a relative icon file name in the query. When there is a lot of data to show in the map, this can significantly reduce the volume of data loaded to the client, which can lead to a significant performance improvement.
For example, if the marker icon needs to be different according to some data value, you can send the data via one of the flex fields, and then write your custom function to set the marker icon depending on the value of the flex field.
You could also modify other characteristics of the marker, such as the title (hover text), info text (popup window), icon anchor point, opacity, and even position (although usually I’d expect your query would provide the correct lat/lng coordinates).
If you have a large number of custom icons you wish to use, along with a large data set of pins to render on the map, you could even compile the icons into a single sprite map to reduce network overhead. This means the image file is loaded once to the client, and then the map “cuts out” bits of the sprite map to render the marker icons. This can be done by setting just a few attributes of the marker’s Icon object. I haven’t tried it myself yet, but this tool looks like it would be useful for this purpose.
Loading Large Datasets
This release adds the Show Spinner and the Rows Per Batch attributes. These attributes are independent of each other, and they help to improve the quality of the experience for your end users when you are rendering a large number of pins on the map.
By default, new maps will have Show Spinner set on. For any existing maps, after upgrading you can turn this option on by setting it in the plugin attributes. This option causes the map to show the default APEX spinner while the data is loaded. The spinner is then removed when the last marker has been rendered. The effect is to give the user an indication that the map is “working”, and gives them immediate feedback when the data has finished loading and they may now interact with the map.
If the spinner seems to stay forever, it may indicate an issue with connectivity to the server (or perhaps that the server is under severe load or has stopped responding to requests).
When the APEX page has been rendered on the client, the Google Map is shown but the data is not immediately loaded; instead, a separate AJAX request is sent to the server to run your query and download all the data to render the pins on the map. By default, this is all done in one single AJAX call, which is the fastest way to get from start to finish; the downside is that the user will not see any pins on the map until all the data has been downloaded. You can change this behaviour by setting Rows Per Batch to some number (e.g. 1000). With this attribute set, the plugin will send a series of AJAX calls to the database (one at a time) and get a batch of records at a time. After loading a batch, the plugin will render the pins on the map (and if necessary, it will pan / zoom the map to show them all) and then send another AJAX request to get the next batch. When it has finished receiving all the batches, it adds any finishing touches needed (e.g. for a visualisation) and returns control to the user.
The advantage of this approach is that the user can see the pins being shown gradually, and they will know that “something is working”. This may help to give them a nicer user experience.
The downside of this approach is that it may cause a bigger load on the server (because each AJAX request requires running a new query, with an offset) and will usually take longer from start to finish. Generally, if your data comprises only a few hundred records at most, you will probably want to leave the Rows Per Batch setting blank.
There are still a few little enhancements on my “todo” list, but I’m keen to hear how you are using (or perhaps planning to use) this plugin, and if there are any new features or improvements that you need or want. If so, please raise them on the GitHub Issues page.
Quite a few people have raised questions or ideas in the past and sometimes I’ve incorporated them straight away, and other times it’s taken a little longer but I get there eventually. If you’re keen to contribute, feel free to have a poke around in the code and perhaps even do a pull request on the GitHub source to suggest a change. It would be great to collaborate with you because everyone has something unique to offer.
Long-term, I’m watching with interest the future direction of Oracle APEX. I remember at one point they were talking about incorporating some sort of new map region into the product, although the mention of this seems to have been dropped from the Statement of Direction (or maybe my memory is misleading me). I guess time will tell.
Font APEX is preferred most of the time but sometimes there are icons I really want to use which are not (yet) included. For these cases I want to load the latest Font Awesome library.
It is possible to load Font Awesome instead of Font APEX by opening Shared Components -> Themes -> Universal Theme, and setting Custom Library File URLs to the location of the library (wherever you have loaded it). However, this replaces the Font APEX font completely so you can’t use both at the same time using this method.
In order to use both at the same time, I’ve downloaded the latest free version of Font Awesome 5 from here (fontawesome.com), taken a copy of the file css/all.css and edited it to replace all occurrences of “.fa” with “.fa5” (if you use CSS precompiler you can do this by editing the appropriate variables file, e.g. _variables.less). This is necessary because the “fa” class prefix would conflict with Font APEX. I named my custom file “fa5.css” and created a minified version as well.
On my web server I created the folder /fa5 under my public html folder, and copied the following files / folders into it:
/fa5/webfonts/* (all contents)
In my APEX application, in the Universal Theme properties I set:
Custom Library File URLs = /fa5/css/fa5#MIN#.css
Custom Prefix Class = fa5
(optional)Custom Classes = (comma-delimited list of your favourite icons)
Alternatively, you could upload the library into your Static Application Files and load them from there.
If I want my page to use an icon from Font APEX, I use the fa- icons as usual, e.g. fa-apex. Where I need an icon from Font Awesome, I have to include both the fa5 class as well as the icon class, e.g. fa5-restroom. For brand icons, of which Font Awesome has a large selection, the class is fa5b, e.g. fa5b fa5-amazon-pay. Font Awesome also includes a range of modifiers including sizes, spin, pulse, rotating, mirroring, and stacking.
You are, of course, asking, can I stack two icons AND spin just one of them? The answer, of course, is yes:
Issue #1: Featured Hero Region Icon
When I tried to use a Font Awesome icon in a Hero region with the “Featured” style, the font failed to load. This is because the “Featured” style overrides the font-family causing it to fail to use the Font Awesome font. To fix this, on the page I added the following CSS:
In a navigation menu, APEX includes the “fa” class which controls the positioning of the icons in the menu, but it also overrides the font library and fails to load the icon from Font Awesome. To fix this, I further edited my fa5.css file (as well as the minified version) to add the following:
The Icon attribute on a region can only be used to provide a class (or list of classes) to serve as the icon for the region. To use a Stacked icon in this case is impossible as the stack must be specified using a span with nested nodes for each icon in the stack. A workaround for this is to use some jQuery to modify the html at runtime, as follows:
Set the region’s Static ID, e.g. stacked
Add this to the page’s Execute When Page Loads (this example is for a Hero region:
It’s a messy kludge, and you’ll have to adapt it if you want to use it in other region templates (check what the span class is), but if this provides significant business benefit then it might be worthwhile.
Comparing Font Awesome 5 Free with Font APEX
I’ve loaded lists of all the icons in the Font Awesome 5 Free and the Font APEX libraries into a table and created a little application that allows me to compare them.
Note: these stats are not perfect because some of the icon names are slightly different between the libraries – for example, all of the “hand” icons have slightly different names between the two libraries.
Oracle has updated apex.oracle.com to APEX 20.1 which includes among other features the new “Friendly URL” option. The legacy URL structure concatenated a string of parameters into a single “p” parameter, which works fine; but it can make it difficult to configure web server rules to match and rewrite URLs. Apart from the application ID or alias (the first part), all the parameters are optional; if all were specified the URL will be something like this (line breaks added for clarity):
When the documentation says the URLs should be “easier to read” I’m pretty sure they mean “by developers”, not end users. I suppose this means the URLs make more sense to developers of other web-based applications, because they conform better to REST URL conventions.
In its simplest form, the URL generated by APEX will include just the workspace path prefix, application, page, and session ID:
Calling APEX_PAGE.GET_URL generates the URLs correctly for the application according to whether the Friendly URL setting is on or not.
I noticed the following features of this new format:
The URL generated by APEX_PAGE.GET_URL now includes a full path (excluding the domain).
Instead of the “c” workspace query parameter, the application’s Path Prefix (which could be set to something other than the workspace name) is used (jk64 in my example). This is not the workspace name, although in most cases it usually will happen to be the same because it’s defaulted that way. This attribute is set at the workspace level, under Administration / Manage Service / Set Workspace Preferences / SQL Workshop.
If not specified, the application and page alias will be used rather than the application or page ID, which is nice.
Even if you specify the application or page alias in uppercase, APEX_PAGE.GET_URL returns them in all lowercase.
The more important attributes relevant to a user navigating the application are now further towards the start of the URL, such as page and item values, so they will be more likely to be noticed by the end user.
The “/r/” bit in the URL is just that. It’s just “r” and can’t be anything else, don’t ask me what it means. EDIT: apparently it stands for “router”…
If your users have bookmarked your application using the legacy URL format, you can still safely upgrade your application to use Friendly URLs because both are still supported. This also means that if you have some old code that generates links programmatically they should still work the same (although it is best practice to call APEX_PAGE.GET_URL for this purpose).
In case you’re wondering, it is not possible to change the URL format when calling APEX_PAGE.GET_URL, it will follow your application’s Friendly URL setting. If you call APEX_PAGE.GET_URL for another application, it will return the correct format of URL for the target application. If you call APEX_PAGE.GET_URL for an application that does not exist, it will return the URL in the legacy format.
Existing applications after upgrading, or ones you import from an older version of APEX, will still use the legacy URL syntax. New applications will use the new Friendly URLs by default – but you can revert them to the legacy URLs if you wish.
On a side note, in earlier versions when you create a new application the application alias was set to the application ID by default. In APEX 20.1, a new application will have an application alias generated from the initial application name; when I tried it, it added a number as well for some reason.
At this very early stage, the legacy URL format is still fully supported – I imagine it will eventually be deprecated, but not yet.