Creating Models

IF you're new to sails, models are the abstractions between tables if we were to speak in a traditional RDBMS language. It presents the schema of your object.

Visit Models & ORM in the docs for more information about using models, datastores, and adapters in your app/microservice.

Creating Models in Sails

The best way to create a new model in sails is to use the CLI.

    sails generate api user

tenantType

In multi tenancy databases, We can define the tenants in which this model will be built. It defaults to ['default'], Meaning the model will be built on the default datastore only.

If specified, all tenant datastores with the specified tenant type property will have the datastore built in them.

  tenantType: ['default', 'school'],
  attributes: {
        ...
  }

Adding attributes

Below, we add full_name, email, and password properties to our model.

attributes: {
      full_name: { type: 'string' },
      email: {type: 'string', unique: true, required: true },
      password: {type: 'string'}
 }

By default, if graph is enabled in the datastore config, the email index with sparse false will be created the moment sails is lifted

Edge Definitions

Edge definitions are put in an edge classType to tell the graph the direction from which an edge makes.

  classType: 'Edge',
  edgeDefinition: {
    from: ['airport'],
    to: ['airport']
  },

  attributes: {
    departureTime: {
      type: 'string'
    },
    ....

In the above example, an edge definition shows a link from one airport to another.

Schema Validations

Since version 3.7.1, ArangDB allows to define schema validations for newly inserted documents or updated documents. This is very useful. This is automatically integrated into sails-arangojs by checking at the rules property of a model attribute.

The rules attribute should be an object that follows the JSON Schema Conventions

the required property is automatically populated from required, defaultsTo properties of an attribute.

To allow for schemaless (Or avoid validations) just add shemaValidation: false property to the model. By default, a model has additionalProperties: true. To enforce validation or opt out of additionalAtrributes, add additionalProperties: false property to the model or additionalProperties: { type: "string" }

json attributes should be accompanined by defaultsTo property to differentiate between arrays and objects.

isIn model validation is converted to enum.

  //shemaValidation: false,
  //additionalProperties: false,

  attributes: {
    RefNo: {
      type: 'string'
      rules: {
        pattern: `^[^A-Z\s]+$` // Dont allow capital letters and spaces
        }
      },
      NationalId: { type: 'string', required: true, rules: {
        pattern: '^[0-9]+$'
      }},
      Address: {
        type: 'json'
        defaultsTo: {},
        rules:{
          linkCollections: [],
          properties: {
            LineI: {type: 'string'},
            Phone: {type: 'string'},
            Email: {type: 'string'}
          },
          required: ['Phone', 'Email']
        }
      }

  }

Referential Integrity

When saving documents, you may want to link documents that refer to each other and maintain referential integrity. ArangoDB used for sails-arangojs has been customized to maintain integrity when certain parameters have been used to save records. For Example, look at the documents below.

  flight: {
    From: {
      _id: "airport/msa",
      id: "msa",
      AirportName: "Mombasa International Airport"
    },
    To: {
      _id: "airport/nbo",
      id: "nbo",
      AirportName: "Jomo Kenyatta International Airport"
    }
  }

The schema definition for the model is as follows:

  ...,
  From: {
        type: 'json'
        defaultsTo: {},
        rules:{
          linkCollections: ['airport'],
          properties: {
            id: {type: 'string'},
            _id: {type: 'string'},
          },
          required: ['id']
        }
  },
  To: {
        type: 'json'
        defaultsTo: {},
        rules:{
          linkCollections: ['airport'],
          properties: {
            id: {type: 'string'},
            _id: {type: 'string'},
          },
          required: ['id']
        }
  },

When saved, it will not be possible to delete vertex airport/msa or airport/nbo because they are used in an edge somewhere or a vertex anywhere else in the database.

Another alternative is to save references as an array.

  // model definition
  Airports: {
        type: 'json'
        defaultsTo: [],
        rules:{
          linkCollections: ['airport'],
          items: {
            type: 'object',
            properties: {
              id: {type: 'string'},
              _id: {type: 'string'},
            },
            required: ['id']
          }
        }
  },

Example document below

   Airports: [
     {
      _id: "airport/msa",
      id: "msa",
      AirportName: "Mombasa International Airport"
    },{
      _id: "airport/nbo",
      id: "nbo",
      AirportName: "Jomo Kenyatta International Airport"
    }

  ],

References can either be recorded in arrays or document as long as the linkCollections property has been set in schema. and the _id field used to save the link.

Additional Features

When defining Models, you can specify the class of the model to be mapped on arangodb. Its alos easy to create custom indexes with a combination of field attributes for your data integrity.

classType: 'Vertex', //Either of Vertex, Edge (default is Vertex)
indexes: [
{ fields: ['Field1', 'Field2']},
{ fields: ['Field2', 'Field3'], unique: true },
],
attributes: {
username: { type: 'string' },
}