DeleteElementTree throws Foreign Key Constraint error when deleting an element that is referenced in other elements as code scope

[DeividasDavidav]

Describe the bug
When using deleteElementTree() function from ElementTreeWalker.ts to delete an element, if an element is referenced by other elements in their code scopes, it throws Foreign key constraint error.

To Reproduce
Steps to reproduce the behavior:

1. Create the first element
2. Create the second element that references the first element in its code scope
3. Use deleteElementTree() on the first element
4. See "error deleting element" error (errorNumber: 65553)

Expected behavior
When deleting an element, processElementTree() function in ElementTreeBottomUp class should also process the elements that reference the element in their code scopes.

Possible solution to this issue:

export abstract class ElementTreeBottomUp {

+ protected shouldVisitCodeScopes(_elementId : string, _scope : ElementTreeWalkerScope) { return true; }

  /** The main tree-walking function */
  protected processElementTree(element: Id64String, scope: ElementTreeWalkerScope) {
    const subModel = this._iModel.models.tryGetModel<Model>(element);
    if (subModel !== undefined) {
      if (this.shouldExploreModel(subModel, scope))
        this._processSubModel(subModel, scope);

      if (this.shouldVisitModel(subModel, scope))
        this.visitModel(subModel, scope);
    }

+   if (this.shouldVisitCodeScopes(element, scope))
+     this._processCodeScopes(element, scope);

    if (this.shouldExploreChildren(element, scope))
      this._processChildren(element, scope);

    if (this.shouldVisitElement(element, scope))
      this.visitElement(element, scope);
  }

+ private _processCodeScopes(element: string, parentScope: ElementTreeWalkerScope) {
+   const scope = new ElementTreeWalkerScope(parentScope, element);
+   this._iModel.withPreparedStatement("select ECInstanceId from bis.Element where CodeScope.id=? and Parent.id is null", stmt => {
+       stmt.bindId(1, element);
+       while (stmt.step() === DbResult.BE_SQLITE_ROW) {
+           const elementId = stmt.getValue(0).getId();
+           this.processElementTree(elementId, scope);
+       }
+   });
+ }
} 

Desktop (please complete the applicable information):

• iTwin.js Version 3.6.1
• Node Version 18.16.0

[pmconne]

The "element tree" is based on parent-child relationships between elements. Your repro steps describe a different relationship, based on code scope. Your second element is therefore not part of the first element's tree and the behavior you describe is expected.

@swwilson-bsi can correct me if I misunderstand.