cli: Fix derived loader failing for entities with Bytes as ids (#1406)

* cli: Fix derived loader issues with Bytes as ids and added tests

* Separate interface test and derived loader test for bytes as ids

.changeset/tall-vans-drop.md

@@ -0,0 +1,5 @@
+---
+'@graphprotocol/graph-cli': minor
+---
+
+Fix derived loaders not working failing for entities with Bytes as ID's

packages/cli/src/codegen/schema.test.ts

@@ -419,11 +419,13 @@ describe('Schema code generator', () => {
     type Worker implements Employee @entity {
       id: Bytes!
       name: String!
+      tasks: [Task!]
    }
 
     type Task @entity {
       id: Bytes!
       employee: Employee!
+      workers: [Worker!] @derivedFrom(field: "tasks")
       worker: Worker!
    }
 `);
@@ -525,6 +527,12 @@ describe('Schema code generator', () => {
           returnType: undefined,
           body: "\n      this.set('worker', Value.fromBytes(value))\n    ",
         },
+        {
+          name: 'get workers',
+          params: [],
+          returnType: new NamedType('WorkerLoader'),
+          body: "\n      return new WorkerLoader('Task', this.get('id')!.toBytes().toHexString(), 'workers')\n    ",
+        },
       ],
     });
   });

packages/cli/src/codegen/schema.ts

@@ -331,12 +331,24 @@ export default class SchemaCodeGenerator {
     const name = fieldDef.name.value;
     const gqlType = fieldDef.type;
     const returnType = this._returnTypeForDervied(gqlType);
+    const obj = this.schema.ast.definitions.find(def => {
+      if (def.kind === 'ObjectTypeDefinition') {
+        const defobj = def as ObjectTypeDefinitionNode;
+        return defobj.name.value == this._baseType(gqlType);
+      }
+      return false;
+    }) as ObjectTypeDefinitionNode;
+
+    const idf = IdField.fromTypeDef(obj);
+    const idIsBytes = idf.typeName() == 'Bytes';
+    const toValueString = idIsBytes ? '.toBytes().toHexString()' : '.toString()';
+
     return tsCodegen.method(
       `get ${name}`,
       [],
       returnType,
       `
-        return new ${returnType}('${entityName}', this.get('id')!.toString(), '${name}')
+        return new ${returnType}('${entityName}', this.get('id')!${toValueString}, '${name}')
       `,
     );
   }