SWhile the HyperCube is the main object for calculating data the ListboxObject is a way to list available values for a field. Its the object behind the listboxes in the Filter Panel. It is also the object used for the listboxes that are created when you click on a field in the selection toolbar.
An example setup from the horizontal listbox extension example, included with the Qlik Sense installation:
This contains defaults for most of the parameters, except the actual field, which the user selects in the property panel, which looks like this:
As you can see the Listbox has either a predefined measure from the library, in which case qListObjectDef.qLibraryId will contain the id of the measure (some UID string) or it has a field name, which will be in the array qListObjectDef.qDef.qFieldDefs at the first position. You don’t really have to bother about which one the user selects to use, the ListboxObject will work the same anyhow.
Frequencies and sort order
There are also some other properties in the ListboxObject that are well known to QlikView users. The frequence mode gives you some additional info on the frequency of the respective values in the ListboxObject. Look to horizontal listbox extension for an example. There is also the qSortCriterias array, which allows you to specify the sort order. The default is to have the selected values first, but you might want to for example keep months order from January to December irrespective of which month is selected.
Mashup editor – even more properties
Like with the Hypercube, you can also build a ListboxObject in the mashup editor. The tool to do this looks like this:
As you can see, you also get the option to include expressions in your listbox, usable if you want to make some calculations for each value in the list. The mashup editor will create a ListboxObject for you like this:
The expressions are added to the ListboxObject in the qExpressions array. In this example I have used predefined measures, but you can also use measures defined in the actual listbox object. The mashup editor includes a expression editor (actually the same used in the Qlik Sense client) to help you with this.
Somtimes your extension does not work as expected. Here are some things you should do
1. Use your favorite browser
The browser that is built in in desktop might cache your extension files, so it is not really suited for extension development. Also in a browser you have better tools for troubleshooting and debugging. I use Google Chrome, since I think the developer tools are pretty good, but other browsers also have developer tools.
2. Look in the browser console
3. Turn off caching
When you are doing extension development the cache is your enemy: caching might mean that you are actually running an older version of your extension than you think. In Chrome you can turn it off in developer tools, in the network tab:
Note that the cache will only be disabled if you have developer tools open, so you should keep them open when developing.
4. Use the developer tools to look at your source code
Open your source code in the browsers developer tools:
Verify that this is the correct version.
5. Use the debugger to step through your code
The developer tools includes a very good debugger. Use it! Good places to set a breakpoint would be:
any methods triggered by an event (click etc)
Note that you can also see the contents of structures like the layout and evaluate expressions used. And, of course step through your code.
6. Verify that you have only one copy of your extension under Extensions folder
Filenames of your qext file needs to be unique. If you are developing on Qlik Sense desktop it is your own responsibility to make sure that this is the case. If you make backup copies of your extension, do not save them under MyDocuments/Qlik/Sense/Extensions.
This post was originally published in Qlik Community: https://community.qlik.com/docs/DOC-8985
Probably the most important object you can have in your Generic Object is the HyperCube. It is what is used in most charts and is the way to tap into engine associative logic and calculation engine. Hypercubes reflect the users selections and calculations will be made on the current selections.
The hypercube properties are in a structure called qHyperCubeDef. A common setup is the one from the peoplechart extension example we have seen before:
This will create a hypercube definition with an empty array of dimensions and an empty array of measures. It will also tell engine to include 2 columns (probably 1 dimension and 1 measure) and 50 rows of data with the initial fetch of data, that is in the reply to the getLayout call. This works because the user can add dimensions and measures using the property panel, which is defined like this:
In a mashup you would in most cases need to list the dimensions and measures you want, something like this (taken from my angular-based mashup example available on GitHub:
This will create a hypercube with eight dimensions and no measures, tell engine that we want all eight columns and 400 rows in the initial fetch, set some other properties and define a call back function called setCases (not included above) that will be called every time the hypercube data has changed.
While it is possible to have a hypercube without dimensions, you probably could use a simple expression instead in most cases. So you normally would have a dimension array. This array should contain one or more NxDimenion object(found here, you need to scroll down a bit). There are two alternatives:
use a predefined dimension from the list of dimensions. If you do that you should set the qLibraryId to the id of the dimension you want to use.
use a dimension that is defined only in this dimension array. In that case you should set qDef to an object that in turn contains the dimension definition. Note that qFieldDefs is actually an array, and so can contain multiple definitions. You can actually define a cyclic group here, though I have never seen it used and don’t think it is supported in the client.
Whether you use a predefined dimension or a locally defined dimension there are some additional properties that might be useful. The most complicated is qOtherTotalSpec, which you can use to limit your hypercube to the top 10 values, or bottom 10 etc.
The measures array works much like the dimensions array. It also has two alternatives: referring to a predefined mease with the qLibraryId field or defining the expression in a qDef structure. Note that the measure qDef structure is not the same as the dimension qDef structure: instead of the qFieldDefs array it holds just a string field (also named qDef) with the actual expression.
Make sure you get some rows
To make sure you actually get some data in your hypercube you need to set the qInitialDataFetch property. This is actually an array, but I have never seen an example with more than one entry in the array. You should set qWidth to the number of columns (that is dimensions plus measures) in your cube and qHeight to the number of rows you need for the initial rendering of your cube.
If you do not set this property, the default is 0 rows and 0 columns, so you will get no data. A very common problem in extension development is that you add dimensions or measures and forget to update the qWidth parameter, so you do not get any values for your measures. Also rememeber that what you specify in your extension is the initial properties, so when you change your code, the objects already created will not change. A way to avoid this problem is to set qWidth to something high (10, for example) since a value that is higher than the actual number of columns will work and get you all columns.
Create a hypercube in the mashup editor
A feature not well known in Qlik Sense mashup editor is that it can help you create a hypercube. In the left column of the editor there is a button labeled ‘Add hypercube’. Select the app you want to work with and click it, and you will get a popup, something like this:
When you click the ‘Add’ button, it will create a createCube call for you, with most of the properties filled in:
Even if you don not use the mashup editor for creating your mashup, this feature can be useful.
Getting data out of a Qlik Sense app is based on a concept called Generic Object. Behind all charts, tables and listboxes in Qlik Sense lies a generic object. Also behind many of the other things you see in the Qlik Sense client lies generic objects:
the selection toolbar
the panel on the left side of the page, with lists of dimensions, measures and master objects
the sheet is a generic object
The purpose of the Generic Object is to make it easier to make client-side changes without having to change the QIX engine. Since the Generic Object is very flexible, many client side changes do not require any changes to the engine. This is in contrast to how it works in QlikView, where all charts have different server-side implementations and client and server code are tightly coupled. This is also a reason why extensions are so powerful in Qlik Sense: to the QIX engine there is really no difference between built-in visualizations and extensions, they are all represented with a Generic Object.
Properties and layout
When you create a Generic Object you define its properties. This is a JSON structure, which you can define yourself. An example (from the peoplechart extension example):
There are two kind of properties:
user defined. Qlik only persists those and include them as-is in the layout, it is up to your code to use them for something
defined by Qlik Engine. These are validated by the Engine, and replaced in Engine output, the layout, by the calculated counterparts.
All properties defined by Engine start with a q, so it is good programming practice to let your own properties start with some other letter. The properties defined by Engine are documented here and the corresponding out data is documented here. Note that properties defined by the Qlik Sense client(like title etc) do NOT start with a q, the QIX engine does not really know what these are used for.
But the parameters known by the QIX Engine will determine the engines calculation. In the output from engine, called layout (though it’s not really the layout of a Generic Object) the definition of those properties will be replaced by the results. A hypercube definition (qHyperCubeDef) will be replaced by a actual hypercube (qHyperCube) containing the results from the calculation.
Generic Object context
Generic objects are everywhere in Qlik Sense. If you are building an extension, you define your Generic Object structure in the initialProperties property. If you are using the mashup API, you create generic objects with the createGenericObject method or one of the wrappers around it (createCube, createList, getList). In both these cases the Qlik Sense client framework will automatically refresh the Generic object with new data when it is invalidated (by for example new selections). If you are working directly on the protocol level, you need to fetch they new data yourself.
The main use of Qlik Sense mashup API is to visualize data from Qlik Sense apps and reuse visualizations in an app, allowing your users to interact with the data. But you can use it for other things to, like running a reload or interacting with Qlik Sense server.
But a Qlik Sense app can be used in two different contexts: desktop and server. While visualizations and interactions with those work the same in Server and Desktop, the server API (which is a REST API, unlike the QIX Engine API which works over the web socket. So the first thing we need to do is check our environment, are we in Server or Desktop. Luckily, there is a method for that, the isPersonalMode method.
Once we know if we are in Desktop or Server we can acct accordingly. If we are in Desktop, we can just call the doReload method. While this might work in Server too, we really shouldn’t use it. In a server environment you might very likely have different Qix Engines for interaction with the user and reloads. In fact it is very likely that the engine we are connected to does not have the right database connections for the reload, so running the reload there would fail. Instead we call the Qlik Server for the reload, and let it determine which computer should do the actual job. We can do this with the callRepository method.
If you are using the Qlik Sense standard client there is a Selection toolbar displayed at the top of the page. It has lots of useful functionality, including search support, so in many cases you would want to use this in a mashup, which is perfectly possible.
But sometimes the selection toolbar does not fit in your web page or you want something more compact. In that case you can listen to selection changes yourself and visualize the selection state.
The way to get the selection state is the getList method. An example:
The reply will contain a qSelectionObject with:
qBackCount and qForwardCount, the number of steps forward and backward that is possible
a qSelections array, with on entry for every field that is selected
the array entries will contain qField – the field name, qTotal – total number of different values in the field and qSelectedCount – the number of selected values
Using this you can make your own visualization of selection state, or perhaps hide and show visualizations based on selection states.
When you use the getObject. call of the Qlik Sense mashup API (also known as the Capabilities API or qlik.js) it works a bit like a black box: you just call it and it will inject some Qlik content into your page , you don’t have to bother about the content, it might be any type of chart, it might even be an extension. But it you want to, you can access the data of the visualization.
The key to this is the return value from getObject. The method returns, as it says in the documentation ‘a promise of an object model’. That means you can use the return value to get access to the data in the visualization, or even call some methods to modify the visualization automatically.
Only you have to understand:
how a promise works
and how to find data in the model you eventually get
The fact that getObject returns a Promise means that you will get an object with a then method. The then method will take a parameter, a function, that is called when getObject is ready, that is after a while, normally just some milliseconds, so to you it will look like immediately, but for the computer this is a long time.
What happens when you call getObject is:
the browser will call the QIX engine over the web socket for the definition of the object with the id you supplied
when the definition comes back it will call the engine to get the data
Only after these two calls will the promise resolve, and the method you supplied as a parameter to the then method will be called. That means that at this stage the object you get will be a model with valid data.
A good way to find out the contents of model is to use the debugger in your browser and inspect it. Some important parts of the model:
layout: this is the data for the visualization. Expressions, hypercubes etc will be evaluated and contain data reflecting the current selections
events, most important is the Validated event, which will be triggered when there is new valid data in the model. a full list is here ( the page refers to AngularJS-based extensions, but this is general, the same events is used for all visualizations, whether they are extensions or not)
So, to sum this up, you can get the title of the visualization like this:
One of the really powerful features of Qlik Sense API’s is the possibility to dynamically modify visualizations. You can build solutions that allows the user not only to make selections and have them reflected in all charts displayed (that’s the default, you will get that automatically if you don’t turn it off) but also to dynamically change chart properties and do things like
change dimension from for example Product to Product Lin (or to Division)
change measure from Sales Amount to Quantity or Margin or Cost
add an additional dimension and make a barchart into a stacked bar chart
limit the chart to only show Top 10, or bottom 5
change the chart type from Barchart to Linechart or to an extension
And all of this can be done for both built-in visualizations and extensions in the same way. The key to all of this is the applyPatches method and soft patches.
A soft patch is a temporary change to properties for a visualization. The fact that it is temporary means:
it will not be persisted either in Desktop or Server
it will not affect other users using the same app
once the Qix engine session is closed it will be gone, so when the user reconnects, visualizations will be back to their original state
the user can make soft patches to visualizations that me does not have the right to modify
You make sure that its a soft patch by setting the second parameter in the applyPatches call to true. The first parameter is the list of patches you want to apply. Since you might want to apply several patches, it is an array, where each entry has three values:
qPath: the path to the property you want to change, with slash (/) where javascrip/json usually has a dot
qOp: the operation you want to perform, one of “add”, “replace”, “remove”
Perhaps this is clearer if we look at an example:
What we do in this example is that we show a list of dimensions and measures to the user. When the user clicks on one of them, we move it to be the first one in the sort order, and use applyPatches to update the array and the chart will be resorted. Since it is all done with soft patches, it will not affect other users.
The Qlik Sense Mashup API (also known as Capabilities API or simply qlik.js) allows you to inject Qlik Sense charts with full interactivity into your web page with just a few lines of code. It also allows you to dynamically define hypercubes, lists or simple expressions, send them to Qlik calculation engine and get results back, so you can visualize the data yourself. If you use the APIs all this would be well known to you. But there is more.. Let’s have a look at some more advanced things you can do.
Show visualizations in a tab
Sometimes you want a user interface that is a bit more advanced than just showing visualizations when the page is loaded. For example you might want to show the visualization in a tab, something like this:
This examples uses jQuery tabs, but you could use any tabs implementation, the basic ideas are the same. What you need to do to make this work:
when the user wants to add a new visualization, call the getObject method, with the html element and the id of the visualization as parameters
when the user switches between tabs, you need to call the resize method, to make sure that the visualization displayed is updated.
A code example. Note that much of this is actually more jQuery than qlik, the only part that is really qlik is the two methods calls:
You’ll find a working example in the Github repository. Note that the key to this is only two calls:
call getObject the first time the user wants to see a new chart, not when the page loads
This is a blog about extending Qlik Sense. Qlik Sense has excellent support for using Qlik objects in your own web page or app. With the tools supplied with the product you can drag-and-drop charts from your Qlik app into a web page and get it injected into basically any web page without programming. That is not what this blog is about.
Looking at the material I have for this blog I realize that some of it (possibly all of it) is not easy. You need to know a bit about programming and have an interest in learning more. You probably also need to know something about Qlik.