Enum ExprReference 

pub enum ExprReference {
    Column(ExprColumn),
    Field {
        nesting: usize,
        index: usize,
    },
    Model {
        nesting: usize,
    },
}

A reference to a model, field, or column.

References use scope-based nesting to support subqueries. A nesting level of 0 refers to the current query scope, while higher levels reference higher scope queries.

Examples

ref(field: 0, nesting: 0)  // field 0 in current query
ref(field: 2, nesting: 1)  // field 2 in parent query
ref(column: 0, table: 1)   // column 0 in table 1

Variants

Column(ExprColumn)

A reference to a column in a database-level statement.

ExprReference::Column represents resolved column references after lowering from the application schema to the database schema. It uses a scope-based approach similar to ExprReference::Field, referencing a specific column within a target at a given nesting level.

Field

Reference a specific field in a query’s relation.

For Query/Delete statements, the relation is the Source. For Insert/Update statements, the relation is the target.

Fields

nesting: usize

Query scope nesting level: 0 = current query, 1+ = higher scope queries

index: usize

Index of the field within the relation

Model

Reference a model at a specific nesting level.

This is roughly referencing the full record instead of a specific field.

Fields

nesting: usize

Implementations

impl ExprReference

pub fn field(field: impl Into<FieldId>) -> ExprReference

pub fn is_field(&self) -> bool

pub fn is_model(&self) -> bool

pub fn column(table: usize, column: usize) -> ExprReference

pub fn is_column(&self) -> bool

pub fn as_expr_column(&self) -> Option<&ExprColumn>

pub fn as_expr_column_unwrap(&self) -> &ExprColumn

pub fn as_expr_column_mut_unwrap(&mut self) -> &mut ExprColumn

Trait Implementations

impl Clone for ExprReference

fn clone(&self) -> ExprReference

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ExprReference

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

Formats the value using the given formatter.

impl From<&ExprReference> for Expr

fn from(value: &ExprReference) -> Expr

Converts to this type from the input type.

impl From<ColumnId> for ExprReference

fn from(value: ColumnId) -> ExprReference

Converts to this type from the input type.

impl From<ExprColumn> for ExprReference

fn from(value: ExprColumn) -> ExprReference

Converts to this type from the input type.

impl From<ExprReference> for Expr

fn from(value: ExprReference) -> Expr

Converts to this type from the input type.

impl Hash for ExprReference

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for ExprReference

fn eq(&self, other: &ExprReference) -> 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 Copy for ExprReference

impl Eq for ExprReference

impl StructuralPartialEq for ExprReference