Models

What is a model?

A model is a definition of a data shape that reflects how the data is stored in the database. Models are similar to GraphQL types, but unlike GraphQL types, Pragma models are defined using the model keyword, all model fields are required by default, and no nullable arrays.

Additionally, models and model fields must have unique positive integer indexes, which are used to make database schema migrations fully automatic. See this important note on indexes.

For example:

@user

@1 model User {

@1 username: String @publicCredential @primary

@2 password: String @secretCredential

}

Here we define a model named User that is annotated with the @user directive, and index 1.

The User model has two fields:

• username, which is given the type: String, and annotated with the @publicCredential directive and @primary directives. Note that every model must have exactly one field annotated with @primary.
• password, which is also given the type: String, and annotated with the @secretCredential directive.

An important note on indexes

caution

Fields and models are identified by their indexes (@1, @2, etc) and names are for generating a human readable GraphQL API.

In other words, if you changed the index of a field or a model, you essentially deleted it and created a new one with the same name, type, and other settings.

We will have warning and error configurations in the future to detect such mistakes before applying the migration.

Relations

Relations between models are encoded as field types. For example:

@user

@1 model User {

@1 username: String @publicCredential @primary

@2 password: String @secretCredential

@3 todos: [Todo]

}

@2 model Todo {

@1 title: String @primary

@2 content: String

}

The todos field on User has the type [Todo] (array of Todos.) This translates to: "a User has many Todos". Similarly, a User can have a reference to a single Todo:

@user @1

model User {

@1 username: String @publicCredential @primary

@2 password: String @secretCredential

@3 priorityTodo: Todo

}

@2 model Todo {

@1 title: String @primary

@2 content: String

}