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Last update: January 30, 2024

How to Extend Dynamic Expression Tree

This article will show you how to extend the existing promotion expression tree of the Marketing module with these new elements:

  • New expression block:

New expression block

  • New block element:

New block element

To view or download our sample code, click here.


Prior to extending your dynamic expression tree, you need to:

Defining New Class for Expression Tree Prototype

The following example creates a new derived prototype from PromotionConditionAndRewardTreePrototype that represents the original expression tree used for marketing promotion. Here, we register a new BlockSampleConditionroot block and extend the existing BlockCatalogCondition with a new element, SampleCondition:

public sealed class SamplePromotionConditionAndRewardTreePrototype : PromotionConditionAndRewardTreePrototype
        public SamplePromotionConditionAndRewardTreePrototype()
            //Extend existing 'If any of these catalog condition' block with a new condition element
            var blockCatalogCondition = AvailableChildren.OfType<BlockCatalogCondition>().FirstOrDefault();
            blockCatalogCondition.AvailableChildren.Add(new SampleCondition());

            // Add a new block with sample condition to the beginning of the tree
            var blockSampleConditions = new BlockSampleCondition().WithAvailConditions(new SampleCondition());
            AvailableChildren.Insert(0, blockSampleConditions);
            Children.Insert(0, blockSampleConditions);

Registering Your Extension in module.cs

The next step includes overriding the original PromotionConditionAndRewardTreePrototype type with the newly created one in the module.cs file:

public void Initialize(IServiceCollection serviceCollection)
            // Override the original expression prototype tree with new type
            AbstractTypeFactory<PromotionConditionAndRewardTreePrototype>.OverrideType<PromotionConditionAndRewardTreePrototype, SamplePromotionConditionAndRewardTreePrototype>();

After that, you need to add a dependency to the Marketing module into the module.manifest file:

        <dependency id="VirtoCommerce.Marketing" version="3.0.0" />


This line is important for correct module initialization order. You can read more about module initialization here.

Defining HTML Templates for New Elements

It is a best practice to define all HTML templates for new elements within an individual file, where the templates will be loaded dynamically as resources.


Make sure to use the following schema as a template ID: expression-{C# element class name}.html.

<script type="text/ng-template" id="expression-BlockSampleCondition.html">
    For condition evaluator with
    <a class="__link" left-click-menu data-target="allAny_menu{{}}">{{element.all | boolToValue:'all':'any'}}</a> of these sample values
    <ul class="menu __context" role="menu" id="allAny_menu{{}}">
        <li class="menu-item" ng-click='element.all=true;'>all</li>
        <li class="menu-item" ng-click='element.all=false;'>any</li>
<script type="text/ng-template" id="expression-SampleCondition.html">
    Sample condition is met: 
    <a class="__link" left-click-menu data-target="yesNo_menu{{}}">{{element1.isSatisfied | boolToValue:'yes':'no'}}</a>
    <ul class="menu __context" role="menu" id="yesNo_menu{{}}">
        <li class="menu-item" ng-click='element1.isSatisfied=true;'>yes</li>
        <li class="menu-item" ng-click='element1.isSatisfied=false;'>no</li>

Registering New Elements in Main module.js File

The next steps include registering newly created expression elements in dynamicExpressionService that is used as a registry for all known tree elements:

angular.module(moduleName, [])
    .run(['virtoCommerce.coreModule.common.dynamicExpressionService', '$http', '$compile',
        function (dynamicExpressionService, $http, $compile) {
            //Register Sample expressions
                id: 'BlockSampleCondition',
                newChildLabel: '+ add sample condition',
                getValidationError: function () {
                    return (this.children && this.children.length) ? undefined : 'Promotion requires at least one eligibility';
                id: 'SampleCondition',
                displayName: 'Sample condition is []'

            $http.get('Modules/$(VirtoCommerce.MarketingSample)/Scripts/all-templates.html').then(function (response) {
                // compile the response, which will put stuff into the cache

Building Your Module and Restarting Platform

You can now build your solution and pack the module scripts with the following command:

npm run webpack:build

After that, you need to restart the platform instance to apply your changes.

Finally, open Platform Manager, go to Marketing>Promotions, and click New promotion. The new For condition evaluator with any of these sample values block with its single Sample condition is met: no/yes line should be there.