Directives

A directive is an annotation that is used to specify certain behavior for a model/model field. Much like GraphQL directives, Pragma directives start with an @ symbol, followed by the name of the directive, and its arguments (if any) which are specified by name.

Fun Fact

"Pragma" is a synonym for "compiler directive", which is where the name of the language (partly) comes from.

The following is a list of all the directives available in Pragma:

Model-level directives

Directives that can be used to mark models.

@user

Used to mark a model as a user model.

@onWrite

Registers a function to be called on CREATE, UPDATE, MUTATE, PUSH_TO, and REMOVE_FROM.

Arguments:

  • function: A function that takes the incoming data, and returns the data to be saved to the database.
note

Functions passed to onWrite, onRead, onDelete, or onLogin can fail by throwing an error. This error will be returned to the user with a failure response.

@onRead

Registers a function to be called on READ, and LIST operation results.

Arguments:

  • function: A function that takes the data coming out of the database, and returns the new data.

@onDelete

Registers a function to be called on DELETE

Arguments:

  • function: A function that takes the data to be deleted, and returns nothing.

@onLogin

Registers a function to be called when a user logs in.

note

Can only be used on user models.

Arguments:

  • function: A function that takes the logged in user, and returns nothing.

Field-level directives

Directives that can be used to mark model fields.

@publicCredential

Marks a field as a public identifier for its user model.

note

Can only be used on user model fields.

@secretCredential

Marks a field as a secret credential for its user model.

note

Can only be used on user model fields.

@unique

Marks a field as being unique for each record.

@autoIncrement

Adds auto-increment functionality.

note

Can only be used on Int fields.

@primary

Marks a field as a primary key.

note

Can only be used on non-optional fields with type String or Int.

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