Bring from mongodb only the fields specified in GraphQL

[rvizzari]

[rvizzari]

Improvement description:

Currently when a graphQl query is executed we are going to mongodb to get this data, but we are bring all the document properties from mongo.
A good improvement should be use the .select() function from mongoose only asking for the specified properties in graphQL query

e.g.

NOW:

graphQL query:

{
  type {
        propertyOne
        propertyTwo
  }
}

Mongo Query:
return Model.find({})

IMPROVEMENT:

Mongo Query:

return Model.find({}).select('propertyOne propertyTwo')

In this way we can make more effective and performant queries

POSSIBLE SOLUTION:

In the graphql query resolve() method, the forth parameter info:

type GraphQLFieldResolveFn = (
  source?: any,
  args?: {[argName: string]: any},
  context?: any,
  info?: GraphQLResolveInfo
) => any

contains more info related about our GraphQL query

I have been playing with this parameters and the fields requested in the graphql query are there and if we catch them this code works fine 😀😀😀:

async resolve (_, _, _, info) {
        const requestedFields = info.fieldNodes[0].selectionSet.selections.map(selection => selection.name.value).join(' ')
        const result = type.model.find({}).select(requestedFields)
        return result
}

I'll leave this here just to not forget and resume this later in a new branch.