Struct diesel::query_builder::UpdateStatement

#[must_use =
  "Queries are only executed when calling `load`, `get_result` or similar."]pub struct UpdateStatement<T, U, V = SetNotCalled, Ret = NoReturningClause> { /* fields omitted */ }

Represents a complete UPDATE statement.

See update for usage examples, or the update guide for a more exhaustive set of examples.

Implementations

impl<T, U> UpdateStatement<T, U, SetNotCalled>

pub fn set<V>(self, values: V) -> UpdateStatement<T, U, V::Changeset> where
    T: Table,
    V: AsChangeset<Target = T>,
    UpdateStatement<T, U, V::Changeset>: AsQuery, 

Provides the SET clause of the UPDATE statement.

See update for usage examples, or the update guide for a more exhaustive set of examples.

impl<T, U, V, Ret> UpdateStatement<T, U, V, Ret>

pub fn filter<Predicate>(self, predicate: Predicate) -> Filter<Self, Predicate> where
    Self: FilterDsl<Predicate>, 

Adds the given predicate to the WHERE clause of the statement being constructed.

If there is already a WHERE clause, the predicate will be appended with AND. There is no difference in behavior between update(table.filter(x)) and update(table).filter(x).

Example

let updated_rows = diesel::update(users)
    .set(name.eq("Jim"))
    .filter(name.eq("Sean"))
    .execute(&connection);
assert_eq!(Ok(1), updated_rows);

let expected_names = vec!["Jim".to_string(), "Tess".to_string()];
let names = users.select(name).order(id).load(&connection);

assert_eq!(Ok(expected_names), names);

pub fn into_boxed<'a, DB>(self) -> IntoBoxed<'a, Self, DB> where
    DB: Backend,
    Self: BoxedDsl<'a, DB>, 

Boxes the WHERE clause of this update statement.

This is useful for cases where you want to conditionally modify a query, but need the type to remain the same. The backend must be specified as part of this. It is not possible to box a query and have it be useable on multiple backends.

A boxed query will incur a minor performance penalty, as the query builder can no longer be inlined by the compiler. For most applications this cost will be minimal.

Example

let mut query = diesel::update(users)
    .set(name.eq("Jerk"))
    .into_boxed();

if !params["tess_has_been_a_jerk"] {
    query = query.filter(name.ne("Tess"));
}

let updated_rows = query.execute(&connection)?;
assert_eq!(1, updated_rows);

let expected_names = vec!["Jerk", "Tess"];
let names = users.select(name).order(id).load::<String>(&connection)?;

assert_eq!(expected_names, names);

impl<T, U, V> UpdateStatement<T, U, V, NoReturningClause>

pub fn returning<E>(
    self,
    returns: E
) -> UpdateStatement<T, U, V, ReturningClause<E>> where
    T: Table,
    UpdateStatement<T, U, V, ReturningClause<E>>: Query, 

Specify what expression is returned after execution of the update.

Examples

Updating a single record:

let updated_name = diesel::update(users.filter(id.eq(1)))
    .set(name.eq("Dean"))
    .returning(name)
    .get_result(&connection);
assert_eq!(Ok("Dean".to_string()), updated_name);

Trait Implementations

impl<T, U, V> AsQuery for UpdateStatement<T, U, V, NoReturningClause> where
    T: Table,
    UpdateStatement<T, U, V, ReturningClause<T::AllColumns>>: Query, 

type SqlType = <Self::Query as Query>::SqlType

The SQL type of Self::Query

type Query = UpdateStatement<T, U, V, ReturningClause<T::AllColumns>>

What kind of query does this type represent?

fn as_query(self) -> Self::Query

Converts a type which semantically represents a SQL query into the actual query being executed. See the trait level docs for more.

impl<'a, T, U, V, Ret, DB> BoxedDsl<'a, DB> for UpdateStatement<T, U, V, Ret> where
    U: Into<BoxedWhereClause<'a, DB>>, 

type Output = BoxedUpdateStatement<'a, DB, T, V, Ret>

The return type of internal_into_boxed

fn internal_into_boxed(self) -> Self::Output

See the trait documentation.

impl<T: Clone, U: Clone, V: Clone, Ret: Clone> Clone for UpdateStatement<T, U, V, Ret>

fn clone(&self) -> UpdateStatement<T, U, V, Ret>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T: Copy, U: Copy, V: Copy, Ret: Copy> Copy for UpdateStatement<T, U, V, Ret>

impl<T: Debug, U: Debug, V: Debug, Ret: Debug> Debug for UpdateStatement<T, U, V, Ret>

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

Formats the value using the given formatter.

impl<T, U, V, Ret, Predicate> FilterDsl<Predicate> for UpdateStatement<T, U, V, Ret> where
    U: WhereAnd<Predicate>,
    Predicate: AppearsOnTable<T>, 

type Output = UpdateStatement<T, U::Output, V, Ret>

The type returned by .filter.

fn filter(self, predicate: Predicate) -> Self::Output

See the trait documentation.

impl<T, U, V, Ret> Query for UpdateStatement<T, U, V, ReturningClause<Ret>> where
    T: Table,
    Ret: Expression + SelectableExpression<T> + NonAggregate, 

type SqlType = Ret::SqlType

The SQL type that this query represents.

impl<T, U, V, Ret, DB> QueryFragment<DB> for UpdateStatement<T, U, V, Ret> where
    DB: Backend,
    T: Table,
    T::FromClause: QueryFragment<DB>,
    U: QueryFragment<DB>,
    V: QueryFragment<DB>,
    Ret: QueryFragment<DB>, 

fn walk_ast(&self, out: AstPass<DB>) -> QueryResult<()>

Walk over this QueryFragment for all passes.

fn to_sql(&self, out: &mut DB::QueryBuilder) -> QueryResult<()>

Converts this QueryFragment to its SQL representation.

fn collect_binds(
    &self,
    out: &mut DB::BindCollector,
    metadata_lookup: &DB::MetadataLookup
) -> QueryResult<()>

Serializes all bind parameters in this query.

fn is_safe_to_cache_prepared(&self) -> QueryResult<bool>

Is this query safe to store in the prepared statement cache?

impl<T, U, V, Ret> QueryId for UpdateStatement<T, U, V, Ret>

type QueryId = ()

A type which uniquely represents Self in a SQL query.

const HAS_STATIC_QUERY_ID: bool

Can the SQL generated by Self be uniquely identified by its type?

fn query_id() -> Option<TypeId>

Returns the type id of Self::QueryId if Self::HAS_STATIC_QUERY_ID. Returns None otherwise.

impl<T, U, V, Ret, Conn> RunQueryDsl<Conn> for UpdateStatement<T, U, V, Ret>

fn execute(self, conn: &Conn) -> QueryResult<usize> where
    Conn: Connection,
    Self: ExecuteDsl<Conn>, 

Executes the given command, returning the number of rows affected.

fn load<U>(self, conn: &Conn) -> QueryResult<Vec<U>> where
    Self: LoadQuery<Conn, U>, 

Executes the given query, returning a Vec with the returned rows.

fn get_result<U>(self, conn: &Conn) -> QueryResult<U> where
    Self: LoadQuery<Conn, U>, 

Runs the command, and returns the affected row.

fn get_results<U>(self, conn: &Conn) -> QueryResult<Vec<U>> where
    Self: LoadQuery<Conn, U>, 

Runs the command, returning an Vec with the affected rows.

fn first<U>(self, conn: &Conn) -> QueryResult<U> where
    Self: LimitDsl,
    Limit<Self>: LoadQuery<Conn, U>, 

Attempts to load a single record.