Relying on GraphQL enums validation in server-side

Question

My question is sort of what is the best practice to do?

I'm creating a backend that uses GraphQL as the API with MongoDB as the datastore. I know that graphql validates the query, in particular the received enums. My question is if it's enough to rely on the GraphQL input enum validation or should I also add validation at the DB level.

I ask this because it seems like a bad practice, and unneeded code duplication. You'll have in two places definitions of the possible enum types, one in the GraphQL schema and one the MongoDB model.

For example:

gql schema:
enum EyeColor {
BROWN
BLUE
GREEN
}
model in mongoose:
new mongoose.Schema({
eyeColor: { type: String, enum: ["BROWN", "BLUE", "GREEN"] }
});

Am i missing something? Is there a better way to declare enums with/in GraphQL or MongoDB? Or maybe it's okay to only rely on GraphQL?

Answer 1

I think that a better way is to define the enum in a const file EyeColor.const.js:

const EYE_COLOR = {
  BROWN: 'BROWN',
  BLUE: 'BLUE',
  GREEN: 'GREEN'
};

export {
  EYE_COLOR
};

And then in your mongoose model file:

import { EYE_COLOR } from '../../consts/EyeColor.const';
import _ from 'lodash';
new mongoose.Schema({ 
 eyeColor: {
    type: String,
    enum: _.values(EYE_COLOR)
  }
}); 

And for the graphql you can dynamically create the String which contains the enum

enum EyeColor {
 BROWN 
 BLUE 
 GREEN 
}

From your object at EyeColor.const.js (I didn't write the code but it should be pretty simple - for each key in your const create another entry in the enum).

This way you have only one definition of your consts.