How do I use GraphQL with Mongoose and MongoDB without creating Mongoose models - mongodb

Question

Creating models in Mongoose is quite pointless since such models are already created with GraphQL and existing constructs (ie TypeScript interface).
How can we get GraphQL to use Mongoose's operations on models supplied from GraphQL without having to recreate models in Mongoose?
Also, it almost seems as if there should be a wrapper for GraphQL that just communicates with the database, avoiding having to write MyModel.findById etc
How does one do that?
Every example on the Internet that talks about GraphQL and Mongodb uses Mongoose.

Answer 1

You should look at GraphQL-to-MongoDB, or how I learned to stop worrying and love generated query APIs. It talks about a middleware package that leverages GraphQL's types to generate your GraphQL API and parses requests sent from clients into MongoDB queries. It more or less skips over Mongoose.
Disclaimer: this is my blog post.
The package generates GraphQL input types for your schema field args, and wraps around the resolve function to parse them into MongoDB queries.
Given a simple GraphQLType:
const PersonType = new GraphQLObjectType({
name: 'PersonType',
fields: () => ({
age: { type: GraphQLInt },
name: {
type: new GraphQLNonNull(new GraphQLObjectType({
name: 'NameType',
fields: () => ({
firstName: { type: GraphQLString },
lastName: { type: GraphQLString }
})
}))
}
})
});
For the most common use case, you'll build a field in the GraphQL schema with a getMongoDbQueryResolver and getGraphQLQueryArgs. The filter, projection, and options provided by the wrapper can be passed directly to the find function.
person: {
type: new GraphQLList(PersonType),
args: getGraphQLQueryArgs(PersonType),
resolve: getMongoDbQueryResolver(PersonType,
async (filter, projection, options, source, args, context) =>
await context.db.collection('person').find(filter, projection, options).toArray()
)
}
An example of a query you could send to such a field:
{
person (
filter: {
age: { GT: 18 },
name: {
firstName: { EQ: "John" }
}
},
sort: { age: DESC },
pagination: { limit: 50 }
) {
name {
lastName
}
age
}
}
There's also a wrapper and argument types generator for mutation fields.