Trait SQLColumn 

pub trait SQLColumn<'a, Value: SQLParam + 'a>:
    SQLColumnInfo
    + Default
    + SQLSchema<'a, &'a str, Value>
    + Expr<'a, Value> {
    type Table: SQLTable<'a, Self::TableType, Value>;
    type TableType: SQLSchemaType;
    type ForeignKeys;
    type Type: TryInto<Value>;

    const PRIMARY_KEY: bool = false;
    const NOT_NULL: bool = false;
    const UNIQUE: bool = false;
    const DEFAULT: Option<Self::Type> = None;

    // Provided methods
    fn default_fn(&'a self) -> Option<impl Fn() -> Self::Type> { ... }
    fn placeholder(
        &self,
        name: &'static str,
    ) -> TypedPlaceholder<<Self as Expr<'a, Value>>::SQLType, <Self as Expr<'a, Value>>::Nullable>
       where Self: Sized { ... }
}

A table column for the dialect whose value type is Value.

Generated by the table macros for each column. A column is also a typed expression (Expr), so it can be selected, compared and passed to SQL functions.

Provided Associated Constants

const PRIMARY_KEY: bool = false

Whether the column is part of the primary key.

const NOT_NULL: bool = false

Whether the column is NOT NULL.

const UNIQUE: bool = false

Whether the column has a UNIQUE constraint.

const DEFAULT: Option<Self::Type> = None

The column’s constant default value, if any.

Required Associated Types

type Table: SQLTable<'a, Self::TableType, Value>

The table the column belongs to.

type TableType: SQLSchemaType

The table’s dialect marker.

type ForeignKeys

The column’s foreign key reference, if any.

type Type: TryInto<Value>

The Rust type of the column’s values.

Provided Methods

fn default_fn(&'a self) -> Option<impl Fn() -> Self::Type>

The function that computes the column’s default on insert, if any (#[column(default_fn = ...)]).

fn placeholder( &self, name: &'static str, ) -> TypedPlaceholder<<Self as Expr<'a, Value>>::SQLType, <Self as Expr<'a, Value>>::Nullable>

where Self: Sized,

Creates a named placeholder with this column’s SQL type and nullability, for use in prepared statements.

The placeholder only binds values the column could hold. See TypedPlaceholder.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementations on Foreign Types

impl<'a, Value, T> SQLColumn<'a, Value> for &T

where Value: SQLParam + 'a, T: SQLColumn<'a, Value>, for<'r> &'r T: SQLColumnInfo + Default + SQLSchema<'a, &'a str, Value> + Expr<'a, Value>,

const PRIMARY_KEY: bool = T::PRIMARY_KEY

const NOT_NULL: bool = T::NOT_NULL

const UNIQUE: bool = T::UNIQUE

const DEFAULT: Option<Self::Type> = T::DEFAULT

type Table = <T as SQLColumn<'a, Value>>::Table

type TableType = <T as SQLColumn<'a, Value>>::TableType

type ForeignKeys = <T as SQLColumn<'a, Value>>::ForeignKeys

type Type = <T as SQLColumn<'a, Value>>::Type

fn default_fn(&'a self) -> Option<impl Fn() -> Self::Type>

Implementors