topic How do you get a measures expression from Hypercube? and is it possible to change it? in Integration, Extension & APIs

How do you get a measures expression from Hypercube? and is it possible to change it?

Tue, 11 Nov 2014 22:00:41 GMT

Hi,

I'm new to extension and Javascript in general. Have started poking around and experimenting with extensions.

I am wondering if it's possible to retrieve the expression of a measure and change it.

And if it's possible how, where and when should you do it.

Best regards

Karl

Re: How do you get a measures expression from Hypercube? and is it possible to change it?

yblake — Wed, 12 Nov 2014 09:28:08 GMT

All measures informations come in : layout.qHyperCube.qMeasureInfo

The Backend API GetMeasureInfos will also return measures informations.

https://help.qlik.com/sense/en-US/developer/#../Subsystems/Workbench/Content/BuildingExtensions/API/backendApi/MethodGet…

Modifying an expression syntax will require use of Mashup API, a good starting point is the createCube method :

https://help.qlik.com/sense/en-US/developer/#../Subsystems/Workbench/Content/BuildingWebsites/API/Methods/MethodCreateCu…

Re: How do you get a measures expression from Hypercube? and is it possible to change it?

ErikWetterberg — Wed, 12 Nov 2014 12:43:45 GMT

Hi Karl,

You could check out this thread.

When you do getProperties() in an extension with a qHyperCubeDef you will get a structure thats described here. The measure will be in qMeasures[index].qDef. Modify it and call setProperties:

var me = this;
this.backendApi.getProperties().then(function(reply){
reply.qHyperCubeDef.qMeasures[0].qDef.qDef = '1+1'; //your new expression
me.backendApi.setProperties(reply);
});

Note that both setProperties and getProperties are asynchronous calls.

Erik

edit: added the trailing );

edit2: added another qDef..

Re: How do you get a measures expression from Hypercube? and is it possible to change it?

Wed, 12 Nov 2014 13:27:58 GMT

Thanks Erik!

There where a type-o in your answer code, so for future readers could you add ); to the end of the codesnippet?

Re: How do you get a measures expression from Hypercube? and is it possible to change it?

ErikWetterberg — Wed, 12 Nov 2014 13:44:20 GMT

OK, fixed. Thanks for pointing that out.

/Erik

Re: How do you get a measures expression from Hypercube? and is it possible to change it?

Wed, 12 Nov 2014 14:14:17 GMT

Found one more thing, there where a qDef missing also. Got a JSON Parse error

reply.qHyperCubeDef.qMeasures[0].qDef.qDef = '1+1'; //your new expression

Re: How do you get a measures expression from Hypercube? and is it possible to change it?

Wed, 12 Nov 2014 14:24:40 GMT

I have one more question, is there a notification when the properties in a hypercube changes?

What I am trying to do is add a set analsysis to a measure and only wan't to do that once every time the user changes/adds a measure.

Re: How do you get a measures expression from Hypercube? and is it possible to change it?

Wed, 12 Nov 2014 14:41:41 GMT

You will get a change notification in the form of a call to the paint method on all invalidations of the object. changing properties are one action that will invalidate for you. reload of data and change of related selections are other.

Re: How do you get a measures expression from Hypercube? and is it possible to change it?

Wed, 12 Nov 2014 14:45:15 GMT

My Javascript knowledge is very limited. I don't understand what you mean, could you explain with a code snippet?

Re: Re: How do you get a measures expression from Hypercube? and is it possible to change it?

Wed, 12 Nov 2014 14:54:33 GMT

define( [
],
function ( ) {
  return {
  paint: function () {
  // This segment will be called every time 
  // the visualization needs to handle the
  // change induced by an invalidation
  }
  };
} );

Re: How do you get a measures expression from Hypercube? and is it possible to change it?

Wed, 12 Nov 2014 15:04:21 GMT

Aha, but there is no specific notification for changes in properties?

So I need to cache my properties and check if they have changed since last time paint was invoked.

Re: How do you get a measures expression from Hypercube? and is it possible to change it?

Thu, 13 Nov 2014 00:22:43 GMT

That is correct. Perhaps something that will be adressed in a later version.

Re: How do you get a measures expression from Hypercube? and is it possible to change it?

Thu, 13 Nov 2014 08:53:18 GMT

Thanks for the references.

qMeasureInfo doesn't include the qDef with the expression as far as I can see. Maybe it should be added in a future release.

Regarding the Mashup API, for a beginner the name of the API is confusing. I thought it where only to be used when creating Mashups. But it's not, right?

I am experimenting with an extension and I want to create 2 new measures based of the measure from the layouts hypercube with some additional set analsysis added. Is it best practise to create another hypercube with the new measures using app.createCube()?

Re: Re: How do you get a measures expression from Hypercube? and is it possible to change it?

ErikWetterberg — Thu, 13 Nov 2014 10:39:10 GMT

Hi Carl,

No you should in most cases not use createCube etc in your extension, they are designed for the pure mashup case, with a web page that connects to Qlik Sense. In an extension you define your hypercube in initialproperties instead.

We are not ready with an API to do this, but you could probably make a partial solution in paint. You would then need to check how many measures are defined and if your extra measures are not there add them. Something like this:

paint : function($element, layout) {
if(this.backendApi.getMeasureInfos().length === 1){
     //only do this if there is only one measure
     var me = this;
     this.backendApi.getProperties().then(function(reply){
          reply.qHyperCubeDef.qMeasures.push({......}); //add measure
          me.backendApi.setProperties(reply);
     });
     //probably dont want to paint with just one measure
     return;
}
//painting with no or several measures
}

But there are some problems with this...The user might not have update rights to the visualization. Also if the user modifies the measure it will probably not work.

Re: How do you get a measures expression from Hypercube? and is it possible to change it?

Thu, 13 Nov 2014 11:14:52 GMT

I get it, and I should probaly work on the visualisation part of my extension instead until the API is more fleshed out.

Do you have a roadmap for the public?

Alot of companies I have seen share their roadmaps on Trello. A great way for the community to see what's coming and a rough when.

Re: Re: How do you get a measures expression from Hypercube? and is it possible to change it?

Fri, 21 Nov 2014 12:03:34 GMT

I made some digging around and found that you can use change and globalChange in properties that seems to works as I want.

change : function(data) {
                                    updateStuff(data);
                                    return true;
                                },

Can you explain what's the difference between change and globalChange?