Struct GuardedUpdate 

pub struct GuardedUpdate<E: EntityTrait> { /* private fields */ }

Implementations

impl<E: EntityTrait> GuardedUpdate<E>

pub fn new(entity: E) -> Self

Start a new builder targeting entity.

pub fn filter<F: IntoCondition>(self, f: F) -> Self

Add a filter expression. Multiple .filter(...) calls AND-combine.

pub fn set_expr(self, col: E::Column, expr: SimpleExpr) -> Self

Set a column to a value-derived expression.

pub fn set_value(self, col: E::Column, value: Value) -> Self

Set a column to a literal value.

pub async fn exec_one<C: ConnectionTrait>( self, conn: &C, ) -> Result<(), GuardedError>

Execute the conditional UPDATE; succeed iff exactly one row matched.

Returns Err(GuardedError::NoRowsAffected) on 0 rows (predicate failure — the race-free “capacity exhausted” signal). Returns Err(GuardedError::TooManyRows { affected }) on >1 rows (filter is not unique-key-equivalent — index/uniqueness bug).

Note on TooManyRows: this variant is preserved for documentation and future-proofing. sea-orm’s UpdateMany::exec returns rows_affected unconditionally on success, so a filter matching >1 rows will mutate every matched row before this post-processor surfaces the error. The variant is the right way to shout when a supposed unique-key-equivalent filter turns out not to be — see Pitfall 4 in 152-RESEARCH.md.

pub async fn exec_at_most_one<C: ConnectionTrait>( self, conn: &C, ) -> Result<bool, GuardedError>

Execute the conditional UPDATE; tolerate 0 rows as a normal outcome.

Returns Ok(true) on 1 row, Ok(false) on 0 rows. >1 rows still returns Err(GuardedError::TooManyRows) — the uniqueness contract is the same.