Model Declaration

derive(Model) macro

At the heart of the orm is the derive macro turning a rust struct into a db model. It uses #[rorm(..)] attributes on fields to provide additional information.

For example a database needs to know how much space a string is expected to occupy:

#[derive(rorm::Model)]
struct User {
    .. // fields missing to be functional

    #[rorm(max_length = 255)]
    username: String,
}

These attributes can be stacked on a field or multiple annotations can be set in a single attribute:

#[derive(rorm::Model)]
struct User {
    .. // fields missing to be functional

    #[rorm(unique)]
    #[rorm(max_length = 255)]
    username: String,

    #[rorm(max_length = 255, unique)]
    email: String,
}

Annotations

Annotations are the extra information defined in the #[rorm(..)] attributes. Some of them map directly to SQL annotations while other are purely for orm purposes.

autoincrement

The autoincrement annotation instructs the database to populate the field using a running counter when creating the rows of this model.

#[derive(rorm::Model)]
struct Order {
    .. // fields missing to be functional

    #[rorm(autoincrement)]
    order_number: u64,
}

auto_create_time and auto_update_time

You can utilize the annotations auto_create_time and auto_update_time to automatically set the current time on creation or on update of the model to the annotated field.

#[derive(rorm::Model)]
struct File {
    .. // fields missing to be functional

    #[rorm(auto_create_time)]
    created: u64,

    #[rorm(auto_update_time)]
    modified: u64,
}

choices

The choices annotation is used to turn a String into an enum by enumerating all available values.

If you prefer actual rust enums, you might want to look at rorm::DbEnum.

#[derive(rorm::Model)]
struct Car {
    .. // fields missing to be functional

    #[rorm(choices("diesel", "gasoline", "electric", "hydrogen", "other"))]
    engine: String,
}

default

A default value to populate this field with, if a new model instance is created without mentioning this field. Note that you need a patch struct to utilize its advantage in the Rust code.

#[derive(rorm::Model)]
struct User {
    .. // fields missing to be functional

    #[rorm(default = false)]
    is_admin: bool,
}

id

Shorthand for both primary_key and autoincrement

index

TODO

max_length

Specify the maximum length a String can have. This is required for every string.

#[derive(rorm::Model)]
struct User {
    .. // fields missing to be functional

    #[rorm(max_length = 255)]
    username: String,
}

primary_key

Marks a field as primary key in the database.

unique

TODO