Fixed the issue of getAllBaseClasses() function not returning all the base classes (backport #8912) [release/5.5.x] (#8918)

Co-authored-by: Soham Bhattacharjee <177123878+soham-bentley@users.noreply.github.com>
Co-authored-by: naveedkhan8067 <38525837+naveedkhan8067@users.noreply.github.com>
Co-authored-by: Nam Le <50554904+hl662@users.noreply.github.com>

Author: 4 people

common/changes/@itwin/ecschema-metadata/soham-bentley-fixing-getbaseclass_2026-01-20-10-44.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@itwin/ecschema-metadata",
+      "comment": "Fixed the issue of getAllBaseClasses() method of ECClass not returning all the base classes",
+      "type": "none"
+    }
+  ],
+  "packageName": "@itwin/ecschema-metadata"
+}

core/ecschema-metadata/src/Metadata/Class.ts

@@ -6,7 +6,7 @@
  * @module Metadata
  */
 
-import { assert } from "@itwin/core-bentley";
+import { assert, Logger } from "@itwin/core-bentley";
 import { DelayedPromiseWithProps } from "../DelayedPromise";
 import { ClassProps } from "../Deserialization/JsonProps";
 import { XmlSerializationUtils } from "../Deserialization/XmlSerializationUtils";
@@ -23,6 +23,8 @@ import { Schema } from "./Schema";
 import { SchemaItem } from "./SchemaItem";
 import { ECSpecVersion, SchemaReadHelper } from "../Deserialization/Helper";
 
+const loggingCategory = "ECClass";
+
 /**
  * A common abstract class for all of the ECClass types.
  * @public @preview
@@ -86,7 +88,13 @@ export abstract class ECClass extends SchemaItem implements CustomAttributeConta
   public async getDerivedClasses(): Promise<ECClass[] | undefined> {
     const derivedClasses: ECClass[] = [];
     for(const derivedClassKey of this.schema.context.classHierarchy.getDerivedClassKeys(this.key)) {
-      const derivedClass = await this.schema.context.getSchemaItem(derivedClassKey, ECClass);
+      let derivedClass = await this.schema.getItem(derivedClassKey.name, ECClass); // if the derived class is in the same schema this will get it without going to the context
+      if (derivedClass) {
+        derivedClasses.push(derivedClass);
+        continue;
+      }
+      Logger.logInfo(loggingCategory, `Derived class ${derivedClassKey.name} not found in schema ${this.schema.name}, looking in schema context.`);
+      derivedClass = await this.schema.context.getSchemaItem(derivedClassKey, ECClass);
       if (derivedClass)
         derivedClasses.push(derivedClass);
     }
@@ -586,20 +594,60 @@ export abstract class ECClass extends SchemaItem implements CustomAttributeConta
    */
   public async *getAllBaseClasses(): AsyncIterable<ECClass> {
     for (const baseClassKey of this.schema.context.classHierarchy.getBaseClassKeys(this.key)) {
-      const baseClass = await this.schema.lookupItem(baseClassKey, ECClass);
+      const baseClass = await this.getClassFromReferencesRecursively(baseClassKey); // Search in schema ref tree all the way to the top
       if (baseClass)
         yield baseClass;
     }
   }
 
+  /**
+   * gets a class from this schema or its references recursively using the item key
+   * @param itemKey
+   * @returns ECClass if it could be found, undefined otherwise
+   * @internal
+   */
+  private async getClassFromReferencesRecursively(itemKey: SchemaItemKey): Promise<ECClass | undefined> {
+    const schemaList: Schema[] = [this.schema];
+    while(schemaList.length > 0) {
+      const currentSchema = schemaList.shift();
+      if(currentSchema!.schemaKey.compareByName(itemKey.schemaKey)) {
+        const baseClass = await currentSchema!.getItem(itemKey.name, ECClass);
+        schemaList.splice(0); // clear the list
+        return baseClass;
+      }
+      schemaList.push(...currentSchema!.references);
+    }
+    return undefined;
+  }
+
   public *getAllBaseClassesSync(): Iterable<AnyClass> {
-    for(const baseClassKey of this.schema.context.classHierarchy.getBaseClassKeys(this.key)) {
-      const baseClass = this.schema.lookupItemSync(baseClassKey, ECClass);
+    for (const baseClassKey of this.schema.context.classHierarchy.getBaseClassKeys(this.key)) {
+      const baseClass = this.getClassFromReferencesRecursivelySync(baseClassKey); // Search in schema ref tree all the way to the top
       if (baseClass)
         yield baseClass;
     }
   }
 
+  /**
+   * gets a class from this schema or its references recursively using the item key synchronously
+   * @param itemKey
+   * @returns ECClass if it could be found, undefined otherwise
+   * @internal
+   */
+  private getClassFromReferencesRecursivelySync(itemKey: SchemaItemKey): ECClass | undefined {
+    const schemaList: Schema[] = [this.schema];
+    while(schemaList.length > 0) {
+      const currentSchema = schemaList.shift();
+      if(currentSchema!.schemaKey.compareByName(itemKey.schemaKey)) {
+        const baseClass = currentSchema!.getItemSync(itemKey.name, ECClass);
+        schemaList.splice(0); // clear the list
+        return baseClass;
+      }
+      schemaList.push(...currentSchema!.references);
+    }
+    return undefined;
+  }
+
   /**
    *
    * @param cache