Query inner object id in a collection using Firestore/ Angularfire2 or Firestore SDK

Question

Could you tell me how to query id of budgetGroup object in budgets collection?

I can do a basic query like below. But how can I query an inner object as mentioned above?

provider.ts

 getSpecificBudget(id:string;budgetGroup: BudgetGroup, projectId: string): AngularFirestoreCollection<Budget> {
    return this.fireStore.collection<Budget>(`projects/${projectId}/budgets`, ref => ref
      .where('id', '==', id)
    );
  }

model.ts

export class Budget {
    id: string;
    amount: number;
    contingency: number = 20;
    budgetGroup: BudgetGroup = new BudgetGroup();
    creationTime: string;
}

export class BudgetGroup {
    id: string;
    name: string;
    creationTime: string;
}

firestore:

Answer 1

This is the solution.We can simply do as shown below. ie .where('budgetGroup.id', '==', budgetGroup.id)

getSpecificBudgetGroupBudget(budgetGroup: BudgetGroup, projectId: string): AngularFirestoreCollection<Budget> {
    return this.fireStore.collection<Budget>(`projects/${projectId}/budgets`, ref => ref
      .where('budgetGroup.id', '==', budgetGroup.id)
    );
  }