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Using Connection Filters for state-based rendering and value formatting


Using Connection Filters for state-based rendering and value formatting

Using Connection Filters for state-based rendering and value formatting

State-based rendering of properties that come from user inputs or from connected ThingWorx data is a common requirement.

Think about the following scenario: from ThingWorx you get the state of a as one of these values: [ OK | At-Risk | Issue ].

You would like to visualize it with a 3D image or a changed 3DGauge icon.

You can achieve that easily with a ThingWorx Studio functionality that is often overseen: The Connection Filters.

With connection filters you can achieve a lot of very nice a common features, mainly:

  • number and date formatting
  • value pre- and postfixing (specifically units for numbers but also anything else)
  • state-based formatting, e.g. changing the image or style based on a number change

Here is what I mean in practice:

Step 1:


Step 2:


Here is the stateBasedStyling Connection Filter content:

return value < 3000 ?

   "fill:rgba(255, 255, 255, 1);textbaseline:middle;textalign:center" :

   "fill:rgba(255,   0,   0, 1);textbaseline:middle;textalign:center" ;

value is a key word and represents the value on the connection before applying the filter function. The returned value is the one that is used in the bound-to attribute. I found that the expression has to be a one-liner (technically), i.e. you have to start your expression with 'return' and can't do something like:

if(value < 3000) return "fill:rgba(255, 255, 255, 1);textbaseline:middle;textalign:center";

else return "fill:rgba(255,   0,   0, 1);textbaseline:middle;textalign:center";

Resulting Filter in ThingWorx Studio:


You can add multiple filters but I didn't check yet in which sequence they'll be evaluated (top-to-bottom or bottom-to-top).

Examples of Usage

1. Show icons for Enum values:

I used it often to display enumerated-type values (i.e. the input values are from a discrete value set e.g.named colors) with images/icons:

return "app/resources/Uploaded/colorImg_"+value+".png"; 

in combination with the corresponding uploaded images, in this case named colorImg_red.png, colorImg_blue.png, etc.

2. Format Numbers and postfix with unit

The following formats the input number 12.769 to 12.8 mph.

return $filter('number')(value, 1) + " mph"; 

See the AngularJS documentation for the available filter types. Relevant are:

I haven't tested yet if these filters can also be applied to input arrays of objects that come from a service (e.g. for a repeater widget). If this is supported the array-based filters may be applicable/usable as well.


Great post,

I only have problems with reading a variabel where I construct the name with the value.

return $["Step"+value];

What I have is a number of application parameters with the name Step1, Step2, Step3 etc and I want the filter to return the value of Step2 when current step in the sequence is "2"

Any typos or is there another way?


Per, you can try assigning a new variable with value as "Step"+value, and use the new variable reference in the params.


Done that without any luck

, also created my own function that I tried to call from the filter without any success.

Manage to get it to work via calling the function from a "value changed" event.

Thanks for the input!


Hi Per,

I have done quite some tests on using $scope parameters in Connection Filters - without luck! It seems that the filter is an encapsulated namespace (it's a closure/lambda expression in fact) and thus doesn't provide access to any parameter outside its own scope.

if you need to combine $scope params with connected and changed values you rather have to use the $scope.$watch AngularJS service. See examples of it:

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