Struct DerivedColumn 

pub struct DerivedColumn<E: Entity> { /* private fields */ }

A column computed dynamically based on other columns or expressions.

Implementations

impl<E: Entity> DerivedColumn<E>

pub fn new(expr: String) -> Self

Creates a new instance.

pub fn alias(alias: &str) -> Self

Constructs an instance for the column alias.

pub fn coalesce<V: IntoSqlValue>(col: E::Column, value: V) -> Self

Constructs an instance using COALESCE to provide a default value for the column.

pub fn coalesce_aggregation<V: IntoSqlValue>( aggregation: Aggregation<E>, value: V, ) -> Self

Constructs an instance using COALESCE to provide a default value for the aggregation.

pub fn year(col: E::Column) -> Self

Constructs an instance for extracting the year from a column.

pub fn year_month(col: E::Column) -> Self

Constructs an instance for extracting the year-month from a column.

pub fn date(col: E::Column) -> Self

Constructs an instance for extracting the date from a column.

pub fn format_date_time(col: E::Column) -> Self

Constructs an instance for formating a date-time as %Y-%m-%d %H:%M:%S.

pub fn json_extract(col: E::Column, path: &str) -> Self

Constructs an instance for extracting values from a JSON column.

Trait Implementations

impl<E: Entity> AsRef<str> for DerivedColumn<E>

fn as_ref(&self) -> &str

Converts this type into a shared reference of the (usually inferred) input type.

impl<E: Clone + Entity> Clone for DerivedColumn<E>

fn clone(&self) -> DerivedColumn<E>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<E: Debug + Entity> Debug for DerivedColumn<E>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<E: Entity> Display for DerivedColumn<E>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<E: Entity> ModelColumn<E> for DerivedColumn<E>

fn into_column_expr(self) -> String

Converts self into a column expression.

impl<E: PartialEq + Entity> PartialEq for DerivedColumn<E>

fn eq(&self, other: &DerivedColumn<E>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<E: Entity> StructuralPartialEq for DerivedColumn<E>