Hapi-sequelize-dynamic-fields

Sometimes we return values at a given endpoint that not always we need all the information, with the plugin you can go through the header which fields you want to return.

For example, we have a model of Tasks (sequelize) that has a relationship for the user. In this way, we could structurer the following query sequelize:

const options = {
  attributes: ['id', 'descriptions', 'observation'],
  include: [{
    model: request.database.User,
    attributes: ['id', 'username', 'lastname', 'email']
  }]
};

In this case, all the fields entered in the attributes properties will be returned, including to the related table. But, will all this information always be used?

We can do in the following manner:

model.findAndCountAll(request.fieldsAll(options));

The plugin provide a call , request.fieldsAll, in which checks if there a property in the header called fields, if there is, the query will be mounted according to the fields informed, in case the field there isn’t, an exception will be thrown AttributesInvalidError.

In the return of our request we can inform which fields are permitted, by the function request.fieldsHeaders, for example:

return reply(values).header('allowing-fields', request.fieldsHeaders(options));

Response Headers:

"allowing-fields": "id,descriptions,observation,User.id,User.username,User.firstName,User.lastName,User.email",

##Example:

####Configuration Hapijs and K7

const Hapi = require('hapi');
const path = require('path');

let server = new Hapi.Server();

const dir = path.join(__dirname, '/models/**.js');

const register = [{
  register: require('k7'),
  options: {
    models: dir,
    adapter: require('k7-sequelize'),
    connectionOptions: {
      options: {
        dialect: 'sqlite'
      }
    }
  }
}, {
  register: require('hapi-sequelize-dynamic-fields')
}];

server.register(register, (err) => {
  if (err) throw err;
});

server.connection();

####Create models

  const User = sequelize.define('User', {
    username: {
      type: DataType.STRING(40),
      allowNull: false,
      unique: true
    },
    firstName: {
      type: DataType.STRING(100),
      allowNull: false,
      field: 'first_name'
    },
    lastName: {
      type: DataType.STRING(50),
      allowNull: false,
      field: 'last_name'
    },
    email: {
      type: DataType.STRING(120),
      allowNull: false,
      unique: true,
      validate: {
        isEmail: true
      }
    },
    password: {
      type: DataType.STRING(200),
      allowNull: false
    }
  }, {
    createdAt: 'created_at',
    updatedAt: 'update_at',
    tableName: 'users'
  });

  const Tasks = sequelize.define('Tasks', {
    descriptions: {
      type: DataType.STRING(200),
      allowNull: false,
      unique: true
    },
    observation: {
      type: DataType.STRING(100),
      allowNull: false
    },
    userId: {
      type: DataType.INTEGER,
      allowNull: false,
      references: {
        model: 'users',
        key: 'id'
      },
      field: 'user_id'
    }
  }, {
    createdAt: 'created_at',
    updatedAt: 'update_at',
    tableName: 'tasks',

    classMethods: {
      associate: (models) => {
        Tasks.belongsTo(models.User, {
          foreignKey: 'userId'
        });
      }
    }
  });

####Create routes

...
 server.route([
    {
      method: 'GET',
      path: '/user',
      config: {
        handler: Controller.list
      }
    },
    {
      method: 'GET',
      path: '/tasks',
      config: {
        handler: Controller.listTasks
      }
    }
  ]);
...    

####Create controllers

export const list = async (request, reply) => {
  try {
    const model = request.database.User;

    const options = {
      attributes: ['id', 'username', 'lastname', 'email'],
    };

    const values = await model.findAndCountAll(request.fieldsAll(options));

    return reply(values).header('allowing-fields', request.fieldsHeaders(options));
  } catch (err) {
    return reply.badImplementation(err);
  }
};

export const listTasks = async (request, reply) => {
  try {
    const model = request.database.Tasks;

    const options = {
      attributes: ['id', 'descriptions', 'observation'],
      include: [{
        model: request.database.User,
        attributes: ['id', 'username', 'lastname', 'email']
      }]
    };

    const values = await model.findAndCountAll(request.fieldsAll(options));

    return reply(values).header('allowing-fields', request.fieldsHeaders(options));
  } catch (err) {
    return reply.badImplementation(err);
  }
};

###Example Users

####request

curl -X GET --header 'Accept: application/json' --header 'fields: id' 'http://localhost:3000/user'

####SQL

SELECT 'id' FROM 'users' AS 'User';

####request

curl -X GET --header 'Accept: application/json' --header 'fields: id, email' 'http://localhost:3000/user'

####SQL

SELECT 'id', 'email' FROM 'users' AS 'User';

####Response Headers { "allowing-fields": "username,firstName,lastName,email", ... }

###Example Tasks

curl -X GET --header 'Accept: application/json' 'http://localhost:3000/tasks'

####SQL

SELECT 
	'Tasks'.'id', 
	'Tasks'.'descriptions', 
	'Tasks'.'observation', 
	'User'.'id' AS 'User.id', 
	'User'.'username' AS 'User.username', 
	'User'.'first_name' AS 'User.firstName', 
	'User'.'last_name' AS 'User.lastName', 
	'User'.'email' AS 'User.email' 
FROM 'tasks' AS 'Tasks' 
LEFT OUTER JOIN 'users' AS 'User' ON 'Tasks'.'user_id' = 'User'.'id';

===

curl -X GET --header 'Accept: application/json' --header 'fields: id, User.id, User.username' 'http://localhost:3000/tasks'

####SQL

SELECT 
	'Tasks'.'id', 
	'User'.'id' AS 'User.id', 
	'User'.'username' AS 'User.username' 
FROM 'tasks' AS 'Tasks' 
LEFT OUTER JOIN 'users' AS 'User' ON 'Tasks'.'user_id' = 'User'.'id';

####Response Headers { "allowing-fields": "id,descriptions,observation,User.id,User.username,User.firstName,User.lastName,User.email", ... }