graphql-to-mongodb

If you want to grant your Nodejs GraphQL service a whole lot of the power of the MongoDb database standing behind it with very little hassle, you've come to the right place!

Examples

Change Log

Blog Post

Lets take a look at the most common use case, ``getMongoDbQueryResolver` and `getGraphQLQueryArgs``:

Given a simple GraphQL type: ```js new GraphQLObjectType({

name: 'PersonType',

fields: () => ({

age: { type: GraphQLInt },

name: { type: new GraphQLObjectType({

name: 'NameType',

fields: () => ({

first: { type: GraphQLString },

last: { type: GraphQLString }

})

}),

fullName: {

type: GraphQLString,

resolve: (obj, args, { db }) => `${obj.name.first} ${obj.name.last}`

}

})

}) ```

An example GraphQL query supported by the package:

Queries the first 50 people, oldest first, over the age of 18, and whose first name is John. ``` {

people (

filter: {

age: { GT: 18 },

name: { 

first: { EQ: "John" } 

}

},

sort: { age: DESC },

pagination: { limit: 50 }

) {

fullName

age

}

} ``` To implement, we'll define the people query field in our GraphQL scheme like so: ```js people: {

type: new GraphQLList(PersonType),

args: getGraphQLQueryArgs(PersonType),

resolve: getMongoDbQueryResolver(PersonType,

async (filter, projection, options, obj, args, context) => {

return await context.db.collection('people').find(filter, projection, options).toArray();

})

} ``` You'll notice that integrating the package takes little more than adding some fancy middleware over the resolve function. The filter, projection, options added as the first paraneters of the callback, can be sent directly to the MongoDB find function as shown. The rest of the parameter are the standard recieved from the GraphQL api.

• Additionally, resolve fields' dependencies should be defined in the GraphQL type like so:

```js 

fullName: {

type: GraphQLString,

resolve: (obj, args, { db }) => `${obj.name.first} ${obj.name.last}`,

dependencies: ['name'] // or ['name.first', 'name.Last'], whatever tickles your fancy

}

```

This is needed to ensure that the projection does not omit any neccessary fields. Alternatively, if throughput is of no concern, the projection can be replaced with an empty object.

• As of mongodb package version 3.0, you should implement the resolve callback as:

```js

return await context.db.collection('people').find(filter, options).toArray();

```

That's it!

The following field is added to the schema (copied from graphiQl): ``` people(

filter: PersonFilterType

sort: PersonSortType

pagination: GraphQLPaginationType

): PersonType ``` PersonFilterType: ``` age: IntFilter name: NameObjectFilterType OR: PersonFilterType AND: PersonFilterType NOR: PersonFilterType ``` \* Filtering is possible over every none resolve field! NameObjectFilterType: ``` first: StringFilter last: StringFilter opr: OprExists ``` OprExists enum tyoe can be EXISTS or NOT_EXISTS, and can be found in nested objects and arrays StringFilter: ``` EQ: String GT: String GTE: String IN: String LT: String LTE: String NEQ: String NIN: String NOT: StringFNotilter ``` PersonSortType: ``` age: SortType ``` SortType enum can be either ASC or DESC GraphQLPaginationType: ``` limit: Int skip: Int ```

Functionality galore! Also permits update, insert, and extensiable custom fields.