Enum Expr 

pub enum Expr {
    Value(Value),
    Field(FieldRef),
    Binary {
        left: Box<Expr>,
        op: BinaryOp,
        right: Box<Expr>,
    },
    Unary {
        op: UnaryOp,
        expr: Box<Expr>,
    },
    Func {
        name: String,
        args: Vec<Expr>,
    },
    Aggregate(AggregationDef),
    Cast {
        expr: Box<Expr>,
        to_type: String,
    },
    Case(CaseDef),
    Window(WindowDef),
    Exists(Box<QueryStmt>),
    SubQuery(Box<QueryStmt>),
    ArraySubQuery(Box<QueryStmt>),
    Collate {
        expr: Box<Expr>,
        collation: String,
    },
    JsonArray(Vec<Expr>),
    JsonObject(Vec<(String, Expr)>),
    JsonAgg {
        expr: Box<Expr>,
        distinct: bool,
        filter: Option<Conditions>,
        order_by: Option<Vec<OrderByDef>>,
    },
    StringAgg {
        expr: Box<Expr>,
        delimiter: String,
        distinct: bool,
        filter: Option<Conditions>,
        order_by: Option<Vec<OrderByDef>>,
    },
    JsonPathText {
        expr: Box<Expr>,
        path: String,
    },
    Now,
    Raw {
        sql: String,
        params: Vec<Value>,
    },
    Custom(Box<dyn CustomExpr>),
}

An expression in a SQL statement.

Variants

Value(Value)

Literal value.

Field(FieldRef)

Column reference.

Binary

Binary operation: left op right.

Fields

left: Box<Expr>

op: BinaryOp

right: Box<Expr>

Unary

Unary operation: -expr, NOT expr.

Fields

op: UnaryOp

expr: Box<Expr>

Func

Function call: name(args...).

Fields

name: String

args: Vec<Expr>

Aggregate(AggregationDef)

Aggregate function: COUNT(expr), SUM(DISTINCT expr) FILTER (WHERE ...).

Cast

Type cast: expr::type (PG) or CAST(expr AS type).

Fields

expr: Box<Expr>

to_type: String

Case(CaseDef)

CASE WHEN … THEN … ELSE … END.

Window(WindowDef)

Window function: expr OVER (PARTITION BY ... ORDER BY ... frame).

Exists(Box<QueryStmt>)

EXISTS (subquery).

SubQuery(Box<QueryStmt>)

Scalar subquery.

ArraySubQuery(Box<QueryStmt>)

ARRAY(subquery).

Collate

Collation override: expr COLLATE "name".

Fields

expr: Box<Expr>

collation: String

JsonArray(Vec<Expr>)

Build a JSON array: PG jsonb_build_array(...), SQLite json_array(...).

JsonObject(Vec<(String, Expr)>)

Build a JSON object: PG jsonb_build_object(k, v, ...), SQLite json_object(k, v, ...).

JsonAgg

Aggregate into JSON array: PG jsonb_agg(...), SQLite json_group_array(...).

Fields

expr: Box<Expr>

distinct: bool

filter: Option<Conditions>

order_by: Option<Vec<OrderByDef>>

StringAgg

Concatenate strings: PG string_agg(expr, delim), SQLite group_concat(expr, delim).

Fields

expr: Box<Expr>

delimiter: String

distinct: bool

filter: Option<Conditions>

order_by: Option<Vec<OrderByDef>>

JsonPathText

JSON text extraction: expr->>'path' on both PG and SQLite. Unlike -> (which returns JSON), ->> returns the value as text.

Fields

expr: Box<Expr>

path: String

Now

Current timestamp: PG now(), SQLite datetime('now').

Raw

Raw SQL with parameters (escape hatch).

Fields

sql: String

params: Vec<Value>

Custom(Box<dyn CustomExpr>)

User-defined expression (extension point).

Implementations

impl Expr

pub fn field(table: &str, name: &str) -> Self

Column reference: table.field.

pub fn value(val: impl Into<Value>) -> Self

Literal value.

pub fn raw(sql: impl Into<String>) -> Self

Raw SQL expression (no parameters).

pub fn func(name: impl Into<String>, args: Vec<Expr>) -> Self

Function call: name(args...).

pub fn cast(expr: Expr, to_type: impl Into<String>) -> Self

Type cast: CAST(expr AS to_type).

pub fn count(expr: Expr) -> Self

COUNT(expr).

pub fn count_all() -> Self

COUNT(*).

pub fn sum(expr: Expr) -> Self

SUM(expr).

pub fn avg(expr: Expr) -> Self

AVG(expr).

pub fn min(expr: Expr) -> Self

MIN(expr).

pub fn max(expr: Expr) -> Self

MAX(expr).

pub fn exists(query: QueryStmt) -> Self

EXISTS (subquery).

pub fn subquery(query: QueryStmt) -> Self

Scalar subquery.

pub fn collate(self, collation: impl Into<String>) -> Self

Collation override: expr COLLATE "name".

pub fn json_array(items: Vec<Expr>) -> Self

Build a JSON array from expressions.

pub fn json_object(pairs: Vec<(impl Into<String>, Expr)>) -> Self

Build a JSON object from key-value pairs.

pub fn json_agg(expr: Expr) -> Self

Aggregate values into a JSON array.

pub fn string_agg(expr: Expr, delimiter: impl Into<String>) -> Self

Concatenate strings with a delimiter.

pub fn json_path_text(expr: Expr, path: impl Into<String>) -> Self

JSON text extraction: expr->>'path'.

pub fn now() -> Self

Current timestamp.

Trait Implementations

impl Clone for Expr

fn clone(&self) -> Expr

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Expr

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

Formats the value using the given formatter.

impl From<FieldRef> for Expr

fn from(f: FieldRef) -> Self

Converts to this type from the input type.

impl From<Value> for Expr

fn from(v: Value) -> Self

Converts to this type from the input type.