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Extending the schema

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The default Guillotine provides fields based on the available schemas.

Sometimes you might want to add/modify/delete fields (new retrieval methods, search in a separate database, virtual fields, etc…​).

The Guillotine schema is entirely configurable. When creating a schema, you can define a listener for a GraphQL type. This listener will be called before the type is created and given the possibility to modify the type creation parameters.

Example: Adding fields

In this example, we have the Author and Post types. But we wish to apply the following modifications:

  • Author should have a new field "fullName" that is the concatenation of firstName and lastName

  • Author data field "email" should require admin rights to be retrieved.

  • Author data field "birthDate" should not be accessible through the GraphQL API.

  • Author should have a new field "posts" returning all the blog posts written by an author

/services/graphql/graphql.js 
var contentLib = require('/lib/xp/content');
var guillotineLib = require('/lib/guillotine');
var graphQlLib = require('/lib/graphql');

var schema = guillotineLib.createSchema({
    creationCallbacks: {
        'com_enonic_app_myapp_Author_Data': function(context, params){ (1)
            params.fields.fullName = {  (2)
                 type: graphQlLib.GraphQLString,
                 resolve: function (env) {
                     return env.source.firstName + ' ' + env.source.lastName;
                 }
             };
            params.fields.email.resolve = function (env) { (3)
                return authLib.hasRole('system.admin') ? env.source.email : null
            };
            delete params.fields.birthDate;  (4)
        },
        'com_enonic_app_myapp_Author': function(context, params){ (1)
            params.fields.posts = { (5)
                type: graphQlLib.list(graphQlLib.reference('com_enonic_app_myapp_Post')),
                resolve: function (env) {
                    return contentLib.query({
                        contentTypes: [app.name + ":Post"],
                        filters: {
                            hasValue: {
                                field: "data.author",
                                values: [env.source._id]
                            }
                        }
                    }).hits;
                }
            };
        }
    }
);

exports.post = function (req) {
    var body = JSON.parse(req.body);
    var result = graphQlLib.execute(schema, body.query, body.variables);
    return {
        contentType: 'application/json',
        body: JSON.stringify(result)
    };
};
1 Passes a callback that will be called before the creation of the specified GraphQL type. It receives the Guillotine context and the object type creation parameters.
2 Adds a new string field "fullName" concatenating two other fields. The resolution function will query contents of type post having the current author ID as field "data.author"
3 Overwrites the resolution function of an existing field "email"
4 Deletes an existing field "birthDate"
5 Adds a new field "posts" returning a list of posts.

These are only examples. You could also modify the type Query and add an entire new API next to the Headless CMS API.

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