Set color by expression in extension

[#1]

Hi all,

I would like to define the coloring option by expression in the properties panel of a visualization extension.

I looked at several extensions and none of them have used any expressions in the properties panel excluding dimension, measure, and appearance > general panes which are all auto created/defined parts of the properties panel, having no setting attributes in the js file.

When I tried the expression: "always" element  in the js file I got the orange fx sign show up in the properties panel but the calculations were not carried out...

Any kind of help would be greatly appreciated!

[jonvitale]

Barnabas,

I wonder if you are still working on this after two months, if so do you have any updates? I'm working on a similar issue, I've gotten maybe one step further, but still a bit lost:

I want to add custom coloring options to my dimensional values. I add new items to my properties panel like this:

dimensions: {

uses: "dimensions",

min: 2,

max: 6,

items: {

colorExpression:{

type: "string",

label: "Enter color expression",

ref:"qDef.myColorSelection.expression",

expression:"always"

}

}

}

This allows me to enter an expression for each dimension within my properties panel user interface. So, if my dimension is called D1 and includes some value like "monkey", I might write:

     = If(D1 = "money", '#665522', '#000000')

Now, if I run the app and break somewhere in the paint function, I'll see the following in

layout.qHyperCube.qDimensionInfo[0].myColorSelection.expression

which evaluates to '#000000' (i.e., the 'else' clause of my expression).

This is not what I want. I do not want a single color for each dimension. I want each different value in the dimension to evaluate to its own color. So 'monkey' values in D1 should be '#665522', 'tiger' should be '#DDCC33', etc.

Hopefully someone picks up this thread. Looking at erik.wetterberg‌ and akl‌

[ErikWetterberg]

Hi,

The easiest way to achieve this is to simply add another measure and use that for color.

Erik Wetterberg

[jonvitale]

Erik,

Thanks for replying, but I'm not sure I understand. I have multiple dimensions that need to be colored independently. I think a close relative of what I'm looking for is in the out-of-the-box Table object. In this object, within the Data tab, you can add multiple Dimensions as columns. Expanding the added dimensions, you get the option of entering a "Background color expression" and a "Text color expression". This is then evaluated on a row-by-row basis in the table.

Any ideas or alternatively, do you know if there is a way to look at the source for the Table object?

[ErikWetterberg]

Hi,

You are right, adding an extra measure is for a one dimension scenario. The built-in table uses qAttributeExpressions, mentioned here. I don't think Qlik has published any property panel component for this, so you have the alternatives of trying to see what the table does or building something yourself.

Erik Wetterberg

[jonvitale]

Erik,

I'll play around with and see what I come up with. By the way, your link was broken for me. But this one seems to work.

I may also open up a new thread about this topic - just in the hopes that someone who knows might stumble by a new question. Seems unlikely, but at least I would be able to curate the thread a bit.

[jonvitale]

erik.wetterberg‌

I was able to successfully color my dimensions by using this as an item in my dimensions.

colorExpression:{
     type: "string",
     label: "Enter color expression",
     ref:"qAttributeExpressions.0.qExpression",
     expression:"optional"
}

This applies the expression to all of the rows in the hypercube matrix. It's very nice. I can then use some app-specific logic to figure out what colors to display to represent the dimensional objects.

However, the problem I'm running into now, is I want another way to color that has nothing to do with dimensions. I'd like to put a "color by expression" somewhere in an "appearance" section of the properties panel. The syntax of the item I use is almost identical to above. However, using the ref "qAttributeExpressions.0.qExpression" doesn't actually run the expression on each row of the matrix. Instead I'll find something like layout.qAttributeExpressions[0].qExpression, with an un-evaluated expression (e.g., "=IF(...)")

Do you know if there is any kind of way to force Qlik to evaluate the expression on each row from within the properties channel? I suppose the other option is to grab the unevaluated color expression in the paint function, evaluate it on each row, and color accordingly.

Thanks - and when I get this all worked out I'll try to put some documentation up so others can benefit.

[ErikWetterberg]

Hi,

If you want it evaluated for each row in the matrix you have as far as I know two alternatives:

• add it as a measure
• use qAttributeExpression

BTW well done with the attribute expression!

Erik Wetterberg

[jonvitale]

erik.wetterberg‌

So, in my app, we are using the first measure for sizing a visualization. I suppose I could make the minimum number of measures 2, and then use the second measure as a color measure.

However, this doesn't seem like good practice. In most of the out-of-the-box visualizations you can create a new measure in the "Appearances" section of the app. This way it is absolutely clear to users that they are making a measure specifically for coloring. As far as you know, is there a way to do this in an extension? Is there a way to tell Qlik that "some expression" should be an attribute of a new measure?

To be perfectly clear, let's say that I have this as part of my definition code:

measures: {
     uses: "measures",
     min: 1,
     max: 3
},
myAppearancePanel: {
     label: "My Appearance Section where you can create a new measure to color the visualization",
     I_Want_A_New_Measure_For_Color:{
          type: "string",
          expression: "optional",
          label: "Color by expression",
          ref:"qAttributeExpressions.0.qExpression"
     }
}

This code is not creating a new measure. It just puts an un-evaluated expression in the layout at qAttributeExpressions[0].qExpression

Thanks again for the help.

[ErikWetterberg]

Hi,

AttributeExpression  will work only in dimensions. I haven't tried this, but you probably could set ref to something like:

qHypercubeDef.qMeasures.1.qDef

Probably the best way is to look at how this is done in the built-in charts.

Hope this helps

Erik Wetterberg