Macro diesel::table

macro_rules! table {
    (
        $name:ident $body:tt
    ) => { ... };
    (
        $schema_name:ident . $name:ident $body:tt
    ) => { ... };
    (
        $name:ident $pk:tt $body:tt
    ) => { ... };
    (
        $schema_name:ident . $name:ident ($pk:ident) $body:tt
    ) => { ... };
    (
        $schema_name:ident . $name:ident ($pk:ident, $($composite_pk:ident),+) {
            $($column_name:ident -> $Type:ty,)+
        }
    ) => { ... };
}

Specifies that a table exists, and what columns it has. This will create a new public module, with the same name, as the name of the table. In this module, you'll find a unit struct named table, and a unit struct with the names of each of the columns. In the definition, you can also specify an additional set of columns which exist, but should not be selected by default (for example, for things like full text search)

By default this allows a maximum of 16 columns per table, in order to reduce compilation time. You can increase this limit to 26 by enabling the large-tables feature, or up to 52 by enabling the huge-tables feature. Enabling huge-tables will substantially increase compile times.

Example usage

table! {
    users {
        id -> Integer,
        name -> VarChar,
        favorite_color -> Nullable<VarChar>,
    }
}

You may also specify a primary key if it's called something other than id. Tables with no primary key, or composite primary containing more than 3 columns are not supported.

table! {
    users (non_standard_primary_key) {
        non_standard_primary_key -> Integer,
        name -> VarChar,
        favorite_color -> Nullable<VarChar>,
    }
}

For tables with composite primary keys, list all of the columns in the primary key.

table! {
    followings (user_id, post_id) {
        user_id -> Integer,
        post_id -> Integer,
        favorited -> Bool,
    }
}

This module will also contain several helper types:

dsl

This simply re-exports the table, renamed to the same name as the module, and each of the columns. This is useful to glob import when you're dealing primarily with one table, to allow writing users.filter(name.eq("Sean")) instead of users::table.filter(users::name.eq("Sean")).

all_columns

A constant will be assigned called all_columns. This is what will be selected if you don't otherwise specify a select clause. It's type will be table::AllColumns. You can also get this value from the Table::all_columns function.

star

This will be the qualified "star" expression for this table (e.g. users.*). Internally, we read columns by index, not by name, so this column is not safe to read data out of, and it has had it's SQL type set to () to prevent accidentally using it as such. It is sometimes useful for count statements however. It can also be accessed through the Table.star() method.

SqlType

A type alias called SqlType will be created. It will be the SQL type of all_columns. The SQL type is needed for things like returning boxed queries.

BoxedQuery

pub type BoxedQuery<'a, DB, ST = SqlType> = BoxedSelectStatement<'a, ST, table, DB>;