feat: provide variables used in feel expressions

Related to camunda/camunda-modeler#5639

Author: Buckwich

lib/base/VariableResolver.js

@@ -159,6 +159,7 @@ export class BaseVariableResolver {
       variables.forEach(variable => {
         const existingVariable = mergedVariables.find(v =>
           v.name === variable.name && v.scope === variable.scope
+          && !v.usedBy && !variable.usedBy
         );
 
         if (existingVariable) {
@@ -251,7 +252,7 @@ export class BaseVariableResolver {
    *
    * @async
    * @param {ModdleElement} element
-   * @returns {Array<ProcessVariable>} variables
+   * @returns {Promise<Array<ProcessVariable>>} variables
    */
   async getVariablesForElement(element) {
     const bo = getBusinessObject(element);
@@ -261,14 +262,14 @@ export class BaseVariableResolver {
 
     // (1) get variables for given scope
     var scopeVariables = allVariables.filter(function(variable) {
-      return variable.scope.id === bo.id;
+      return variable.scope && variable.scope.id === bo.id;
     });
 
     // (2) get variables for parent scopes
     var parents = getParents(bo);
 
     var parentsScopeVariables = allVariables.filter(function(variable) {
-      return parents.find(function(parent) {
+      return variable.scope && parents.find(function(parent) {
         return parent.id === variable.scope.id;
       });
     });
@@ -294,6 +295,31 @@ export class BaseVariableResolver {
       return false;
     });
   }
+
+  /**
+   * Returns consumed variables for an element — variables
+   * the element needs as input for its expressions and mappings.
+   *
+   * Uses `getVariables()` instead of `getVariablesForElement()` to
+   * bypass the name-based deduplication that would drop requirement
+   * entries for variables that also exist in ancestor scopes.
+   *
+   * @param {Object} element
+   * @returns {Promise<Array<ProcessVariable>>}
+   */
+  async getConsumedVariablesForElement(element) {
+    const allVariablesByRoot = await this.getVariables()
+      .catch(() => {
+        return {};
+      });
+
+    const allVariables = Object.values(allVariablesByRoot).flat();
+
+    return allVariables.filter(v =>
+      v.usedBy && v.usedBy.length > 0
+      && v.origin.length === 1 && v.origin[0].id === element.id
+    );
+  }
 }
 
 BaseVariableResolver.$inject = [ 'eventBus', 'bpmnjs' ];

lib/zeebe/VariableResolver.js

@@ -98,9 +98,9 @@ export default class ZeebeVariableResolver extends BaseVariableResolver {
 
     for (const key in rawVariables) {
       const variables = rawVariables[key];
-      const newVariables = parseVariables(variables);
+      const { resolvedVariables, consumedVariables } = parseVariables(variables);
 
-      mappedVariables[key] = [ ...variables, ...newVariables ];
+      mappedVariables[key] = [ ...variables, ...resolvedVariables, ...consumedVariables ];
     }
 
     context.variables = mappedVariables;