Custom rules ignored

[philippfromme]

Due to the way BpmnRules is implemented some rules can be used directly without the use of Rules#allowed. Therefore they can't be overridden by custom rules. This leads to a lot of frustration when people want to do exactly that.

Example:

// BpmnRules.js
function canConnect(source, target, connection) {
  // ...
}

BpmnRules.prototype.canConnect = canConnect; // ignores rules.allowed

is used directly

// Modeling.js

Modeling.prototype.connect = function(source, target, attrs, hints) {

  var bpmnRules = this._bpmnRules;

  if (!attrs) {
    attrs = bpmnRules.canConnect(source, target); // use rules.allowed('connection.create', ...) instead
  }

  if (!attrs) {
    return;
  }

  return this.createConnection(source, target, attrs, source.parent, hints);
};

Improvement

• make sure BpmnRules uses 'rules.allowed' which will ensure that rules can be overridden

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Related to this forum post

[jan-ladleif]

Sorry to intrude, but this seems related to two issues I had when adding custom rules for chor-js.

1. Basically what @philippfromme said: Since various classes call bpmnRules directly, e.g. bpmnRules.canConnect(source, target), one can not add refinements or additions to these rules by adding another RuleProvider. Instead, we need to override BpmnRules and inject our version globally (see our code).

2. The rules themselves often call local helper functions instead of prototype functions. Example: The rule for connection.create calls the local canConnect(...) instead of the prototype variant.

   As a consequence, just overriding the prototype method has no effect. That's why we had to copy the code of all the rules to make sure they call the prototype.