Module types 

Mapping between Rust field types, SQL column types and Value.

DbType is implemented for every type a model field may have. The Model derive uses DbType::SQL_TYPE and DbType::NULLABLE for migration metadata and DbType::to_value / DbType::from_value for writes and reads.

Canonical storage forms

Backends without a native column type store a canonical form, and from_value accepts both the native value and that form:

Rust type	Native Value	Canonical fallback
bool	Bool	Int 0/1
Decimal	Decimal	Text ("12.50"), Int, Float
Uuid	Uuid	Text (hyphenated) or 16 Bytes
NaiveDate	Date	Text DATE_FORMAT
NaiveTime	Time	Text TIME_FORMAT
DateTime<Utc>	Timestamp	Text TIMESTAMP_FORMAT (fixed width, so text order = time order)
TimeDelta	Int (microseconds)	—
IpAddr	Text	—
serde_json::Value	Json	Text holding JSON

Integer and float types also accept Decimal (integral, respectively any value), because PostgreSQL returns numeric for SUM and AVG. On SQLite, declare Decimal columns NUMERIC: the canonical text form would otherwise sort and aggregate as text.

Enums

SqlType

Portable column type family. Backends map it to concrete DDL.

Constants

DATE_FORMAT

Text form of dates on backends without a native date type.

TIMESTAMP_FORMAT

Text form of UTC timestamps (always 6 fractional digits and Z).

TIME_FORMAT

Text form of times of day.

Traits

DbType

A Rust type that can be stored in a model column.

Functions

canonical_text

Canonical text for values a backend cannot store natively (see module docs).

decode

Decode column column of value as T, naming the column on failure.