Trait sqlx::Type[][src]

pub trait Type<DB> where
    DB: Database
{ fn type_info() -> <DB as Database>::TypeInfo; fn compatible(ty: &<DB as Database>::TypeInfo) -> bool { ... } }
Expand description

Indicates that a SQL type is supported for a database.

Compile-time verification

With compile-time verification, the use of type overrides is currently required to make use of any user-defined types.

struct MyUser { id: UserId, name: String }

// fetch all properties from user and override the type in Rust for `id`
let user = query_as!(MyUser, r#"SELECT users.*, id as "id: UserId" FROM users"#)


This trait can be derived by SQLx to support Rust-only wrapper types, enumerations, and (for postgres) structured records. Additionally, an implementation of Encode and Decode is generated.


Rust-only domain or wrappers around SQL types. The generated implementations directly delegate to the implementation of the inner type.

struct UserId(i64);
  • #[sqlx(type_name = "<SQL type name>")] on struct definition: instead of inferring the SQL type name from the inner field (in the above case, BIGINT), explicitly set it to <SQL type name> instead. May trigger errors or unexpected behavior if the encoding of the given type is different than that of the inferred type (e.g. if you rename the above to VARCHAR). Affects Postgres only.
  • #[sqlx(rename_all = "<strategy>")] on struct definition: See derive docs in FromRow


Enumerations may be defined in Rust and can match SQL by integer discriminant or variant name.

With #[repr(_)] the integer representation is used when converting from/to SQL and expects that SQL type (e.g., INT). Without, the names of the variants are used instead and expects a textual SQL type (e.g., VARCHAR, TEXT).

enum Color { Red = 1, Green = 2, Blue = 3 }
#[sqlx(type_name = "color")] // only for PostgreSQL to match a type definition
#[sqlx(rename_all = "lowercase")]
enum Color { Red, Green, Blue }


User-defined composite types are supported through deriving a struct.

This is only supported for PostgreSQL.

#[sqlx(type_name = "interface_type")]
struct InterfaceType {
    name: String,
    supplier_id: i32,
    price: f64

Required methods

Returns the canonical SQL type for this Rust type.

When binding arguments, this is used to tell the database what is about to be sent; which, the database then uses to guide query plans. This can be overridden by Encode::produces.

A map of SQL types to Rust types is populated with this and used to determine the type that is returned from the anonymous struct type from query!.

Provided methods

Determines if this Rust type is compatible with the given SQL type.

When decoding values from a row, this method is checked to determine if we should continue or raise a runtime type mismatch error.

When binding arguments with query! or query_as!, this method is consulted to determine if the Rust type is acceptable.

Implementations on Foreign Types