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0.1.1 | Sep 6, 2023 |
0.1.0 | Sep 6, 2023 |
#818 in Procedural macros
10KB
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Diesel Enum Derivation for FromSql
and ToSql
This procedural macro simplifies the process of generating Diesel FromSql
and ToSql
instances for enums with a specific SqlType
. It is designed for use with Diesel and Postgres, utilizing ToString
and FromStr
traits as the base for conversion. This macro generates the necessary boilerplate code for handling enum conversions between Rust and SQL.
Table of Contents
Usage
To use this procedural macro, you'll need to add the enum_diesel_macros
crate to your project's dependencies in Cargo.toml
. You can then derive the necessary implementations for your enums. Below is an example of how to use the FromToSql
macro:
#[derive(Debug, PartialEq, EnumString, Display, FromToSql)]
#[fromtosql(sql_type = MyEntityEnumSqlType)]
enum MyEntityEnum {
#[strum(serialize = "ONE")]
EnumOne,
#[strum(serialize = "TWO")]
EnumTwo,
}
Make sure to import the required dependencies and modules as shown in the example.
Example
Here's a step-by-step example of how to use the FromToSql
macro to generate Diesel FromSql
and ToSql
instances for your enum:
- Define your custom SQL type using Diesel's
SqlType
and annotate it with diesel attributes:
pub mod schema {
pub mod sql_types {
#[derive(diesel::sql_types::SqlType)]
#[diesel(postgres_type(name = "myentittyenumsqltype", schema = "myschema"))]
pub struct MyEntityEnumSqlType;
}
}
- Import the necessary Diesel and procedural macro dependencies:
#[derive(Debug, PartialEq, EnumString, Display, FromToSql)]
#[fromtosql(sql_type = MyEntityEnumSqlType)]
enum MyEntityEnum {
#[strum(serialize = "ONE")]
EnumOne,
#[strum(serialize = "TWO")]
EnumTwo,
}
- Now, you can use your
MyEntityEnum
enum seamlessly with Diesel queries.
Enums and SqlTypes
The key to using this macro is to ensure that you have a corresponding SqlType
defined for your enum. In this example, MyEntityEnumSqlType
represents the SQL type for the MyEntityEnum
enum. This SqlType
is generated in Diesel schemas and serves as the companion enum to MyEntityEnum
.
Ensure that your enum also implements either the FromStr
or EnumString
trait, which is crucial for parsing the enum from SQL values.
Dependencies
To use this procedural macro, make sure to include the following dependencies in your Cargo.toml
:
[dependencies]
diesel = { version = "2.1", features = ["postgres"] }
strum = "0.25"
strum_macros = "0.25"
diesel-sqltype-enum-pg = "0.1.0"
Dependencies
~3.5MB
~71K SLoC