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A GraysQL extension to load a GraphQL schema from an ORM.
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README.md

GraysQL ORM Loader

GraysQL ORM Loader is an extension for GraysQL that transforms your existent ORM models/schema into a GraphQL Schema. In order to do the transformation, this extension needs an ORM translator. The translator will take care of the implementation details of the ORM and will get the data that ORM Loader needs.

If the ORM that you use doesn't have a translator, you can build it yourself using the Translators API.

Installation

Install this package from npm using the following command:

$ npm install graysql-ext-orm-loader

Note that this is an extension for GraysQL, so you must have it installed in order for this to work.

Translators

Example

Here is a simple example using Sails.js with Waterline as the ORM.

const GraysQL = require('graysql');
const ORMLoader = require('graysql-orm-loader');
const WaterlineTranslator = require('graysql-orm-loader-waterline');  // We'll use the waterline translator

const GQL = new GraysQL();

// Add the extension to GQL
GQL.use(ORMLoader);

// Instantiate the translator and pass the sails models.
GQL.loadFromORM(new WaterlineTranslator(sails.models));

// Generate the schema
const Schema = GQL.generateSchema();
console.log(Schema);

Overview

In order to load a Schema from the ORM you will need a translator. Then, this library will use that translator to retrieve the necessary information from the ORM and load it into GraysQL. This loader will create the following objects for each model.

  • Types: A valid GraysQL Type for every model in the ORM.
  • Queries: For each type created, these queries will be created too:
    • type(id: Int): Type: Gets a single type by its id.
    • types(): [Type]: Gets all the types.
  • Mutations: For each type created, these mutations will be created too:
  • createType(args): Creates a type.
  • updateType(args): Updates a type.
  • deleteType(args): Deletes a type.

If you don't want to create all the mutations by default, you can customize what mutations the loader will create automatically.

Methods

This extension adds the following method to GraysQL.

GQL.loadFromORM(translator, [options])

Receives an instance of an ORM Translator and will use this translator to load all the models into GraysQL.

  • Parameters:

    • translator Object: An instance of a valid translator.
    • options Object: A configuration object with the following keys and default values:
    {
      relay: false,  // Create valid relay types instead of default ones.
      mutations: {
        create: true,  // Indicates if a create mutation shoud be created.
        update: true,  // Indicates if a update mutation should be creted.
        delete: true   // Indicates if a delete mutation should be created.
      }
    }

Translators API

A translator is simply an object that implements certain methods. As long as the result is this object, it can be a class, a raw object, a function, etc. There is a mock translator in the tests folder that you can take as example. Usually, but not necessarily, a translator implements a method to receive the models that it should translate from.

The methods that translators must implement are:

getModelsNames()

Returns an array with the name of all the models in the translators.

  • Returns
    • Array: String: An array containing the names of the models inside the translator.
const expected = ['Group', 'User'];
const result = translator.getModelsNames();
expect(result).to.deep.equal(expected);

parseModelProperties(modelName)

Returns the parsed properties of the model indicated with modelName argument. Only the properties are parsed here, ignore the relationships. The returned properties object should be an object with keys as the names of GraysQL Types fields, and the value as the fields.

  • Parameters
    • modelName String: The name of the model to parse.
  • Returns
    • Object: An object containing the parsed properties.
const expected = {
  id: {
    type: 'Int'
  },
  nick: {
    type: 'String'
  }
};
const result = translator.parseModelProperties('User');
expect(result).to.deep.equal(expected);

parseModelAssociations(modelName)

Returns the parsed associations of the model indicated with modelName argument. ONly the associations are parsed here, ignore the properties. The returned associations object should be an object with keys as the names of GraysQL Types fields, and the value as the fields.

  • Parameters
    • modelName String: The name of the model to parse.
  • Returns
    • Object: An object containing the parsed associations.
const expected = {
  members: {
    tye: '[User]'
  }
};
const result = translator.parseModelAssociations('Group');
expect(result).to.deep.equal(expected);

getArgsForCreate(modelName)

Should return an object containing the necessary arguments to create a new entity of the model indicated with modelName. The keys of the object are the arguments names and the values are the arguments types.

  • Parameters
    • modelName String: The name of the model from which get the arguments.
  • Returns
    • Object: The necessary arguments to create a new entity.
const expected = {
  nick: {
    type: 'String!'  // The nick of the user that it's about to be created
  }
};
const result = translator.getArgsForCreate('User');
expect(result).to.deep.equal(expected);

getArgsForUpdate(modelName)

Should return an object containing the necessary arguments to update an entity of the model indicated with modelName. The keys of the object are the arguments names and the values are the arguments types.

  • Parameters
    • modelName String: The name of the model from which get the arguments.
  • Returns
    • Object: The necessary arguments to update an entity.
const expected = {
  id: {
    type: 'Int!',
  },
  nick: {
    type: 'String!'  // The new nick of the user
  }
};
const result = translator.getArgsForUpdate('User');
expect(result).to.deep.equal(expected);

getArgsForDelete(modelName)

Should return an object containing the necessary arguments to delete an entity of the model indicated with modelName. The keys of the object are the arguments names and the values are the arguments types.

  • Parameters
    • modelName String: The name of the model from which get the arguments.
  • Returns
    • Object: The necessary arguments to delete an entity.
const expected = {
  id: {
    type: 'Int!',
  }
};
const result = translator.getArgsForDelete('User');
expect(result).to.deep.equal(expected);

resolveById(modelName)

Should return a function that takes the same parameters as a resolve function from GraphQL and returns the resolved entity by id. The id of the entity to returns is in the args parameter.

  • Parameters
    • modelName String: The name of the model from which resolve the entity.
  • Returns
    • Function: The resolve function.
const expected = (root, args) => DB.getUser(args.id);
const result = translator.resolveById('User');
expect(result).to.equal(expected);

resolveAll(modelName)

Should return a function that takes the same parameters as a resolve function from GraphQL and returns all the entities of the model.

  • Parameters
    • modelName String: The name of the model from which resolve the entities.
  • Returns
    • Function: The resolve function.
const expected = (root, args) => DB.getUsers();
const result = translator.resolveAll('User');
expect(result).to.equal(expected);

resolveCreate(modelName)

Should return a function that takes the same parameters as a resolve function from GraphQL and creates a new entity of the model.

  • Parameters
    • modelName String: The name of the model from which create the entity.
  • Returns
    • Function: The resolve function.
const expected = (root, args) => DB.createUser(args.nick);
const result = translator.resolveCreate('User');
expect(result).to.equal(expected);

resolveUpdate(modelName)

Should return a function that takes the same parameters as a resolve function from GraphQL and updates an entity of the model.

  • Parameters
    • modelName String: The name of the model from which update the entity.
  • Returns
    • Function: The resolve function.
const expected = (root, args) => DB.updateUser(args.id, args.nick);
const result = translator.resolveUpdate('User');
expect(result).to.equal(expected);

resolveDelete(modelName)

Should return a function that takes the same parameters as a resolve function from GraphQL and deletes an entity of the model.

  • Parameters
    • modelName String: The name of the model from which delete the entity.
  • Returns
    • Function: The resolve function.
const expected = (root, args) => DB.deleteUser(args.id);
const result = translator.resolveDelete('User');
expect(result).to.equal(expected);

resolveNodeId(modelName)

Should return a function that takes an id as parameter and returns an entity with the same id of the model specified with modelName. Only used if the option option.relay is set to true.

  • Parameters
    • modelName String: The name of the model from which get the entity.
  • Returns
    • Function: The nodeId function.
const expected = (id) => DB.getUser(id);
const result = translator.resolveNodeId('User');
expect(result).to.equal(expected);

resolveIsTypeOf(modelName)

Should return a function that takes an object as parameter and returns true or false depending of the type of the object. Is the same as the function isTypeOf of GraphQL.

  • Parameters
    • modelName String: The name of the model from which resolve the type.
  • Returns
    • Function: The isTypeOf function.
const expected = (obj) => obj instanceof DB.User;
const result = translator.resolveIsTypeOf('User');
expect(result).to.equal(expected);

Examples

An usage example can be found in example directory.

Tests

The tests are written with mocha and can be run with the following command:

$ npm test

To get a code coverage report, run the following command:

$ npm run cover

TODO

  • Use GraphQLInputType for mutations instead of passing arguments one by one.

License

MIT

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