Handling Mongoose Populated Fields in GraphQL

Question

How do I represent a field that could be either a simple ObjectId string or a populated Object Entity?

I have a Mongoose Schema that represents a \'Device t

Answer 1

I was trying to solve the general problem of pulling relational data when I came across this article. To be clear, the original question appears to be how to dynamically resolve data when the field may contain either the ObjectId or the Object, however I don't believe it's good design in the first place to have a field store either object or objectId. Accordingly, I was interested in solving the simplified scenario where I keep the fields separated -- one for the Id, and the other for the object. I also, thought employing Unions was overly complex unless you actually have another scenario like those described in the docs referenced above. I figured the solution below may interest others also...

Note: I'm using graphql-tools so my types are written schema language syntax. So, if you have a User Type that has fields like this:

type User {
    _id: ID
    firstName: String
    lastName: String
    companyId: ID
    company: Company
}

Then in my user resolver functions code, I add this:

  User: {   // <-- this refers to the User Type in Graphql
    company(u) {   // <-- this refers to the company field
      return User.findOne({ _id: u.companyId }); // <-- mongoose User type
    },
  }

The above works alongside the User resolver functions already in place, and allow you write GQL queries like this:

query getUserById($_id:ID!) 
    { getUserById(_id:$_id) {
    _id
    firstName
    lastName
    company {
        name
    }
    companyId
    }}

Regards,

S. Arora