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    graphql-to-mongodb
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    1.6.5 • Public • Published

    graphql-to-mongodb

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    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:

    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:

    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:
      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:
      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.

    Install

    npm i graphql-to-mongodb

    DownloadsWeekly Downloads

    348

    Version

    1.6.5

    License

    MIT

    Unpacked Size

    86 kB

    Total Files

    33

    Last publish

    Collaborators

    • npmsoluto