title: GraphQL query using _id String, with Object ID stored in MongoDB
body: <p>Having trouble getting my graphql query to return anything when sending the _id as a string. If instead, I query the DB using any other stored key (for example, name: &quot;Account 1&quot;), it works great and returns the object. My Account schema uses type: GraphQLString for the _id, but i've also tried using GraphQLID and neither have been successful.</p>
  <pre><code>const AccountType = new GraphQLObjectType({
      name: 'Account',
      fields: () =&gt; ({
          _id: { type: GraphQLString },
          name: { type: GraphQLString },
          balance: { type: GraphQLInt },
      })
  });
  
  const RootQuery = new GraphQLObjectType({
      name: 'RootQueryType',
      fields: {
          getAccounts: {
              type: AccountType,
              args: { _id: { type: GraphQLString } },
              async resolve(parentValue, args, context) {
                  console.log(args._id)
                  return context.mongo.Accounts.findOne({ _id: args._id })
                      .then(response =&gt; console.log(response))
              }
          }
      }
  });
  </code></pre>
  <p>In my MongoDB collection, the _id is stored as Object IDs. Wondering if it doesn't recognize the string as the Object ID stored? Any help is appreciated.</p>