Trait QueryFragment

Source

pub trait QueryFragment<DB: Backend, SP = NotSpecialized> {
    // Required method
    fn walk_ast<'b>(&'b self, pass: AstPass<'_, 'b, DB>) -> QueryResult<()>;

    // Provided methods
    fn to_sql(
        &self,
        out: &mut DB::QueryBuilder,
        backend: &DB,
    ) -> QueryResult<()> { ... }
    fn collect_binds<'b>(
        &'b self,
        out: &mut DB::BindCollector<'b>,
        metadata_lookup: &mut DB::MetadataLookup,
        backend: &'b DB,
    ) -> QueryResult<()> { ... }
    fn is_safe_to_cache_prepared(&self, backend: &DB) -> QueryResult<bool> { ... }
    fn is_noop(&self, backend: &DB) -> QueryResult<bool> { ... }
}

Expand description

An untyped fragment of SQL.

This may be a complete SQL command (such as an update statement without a RETURNING clause), or a subsection (such as our internal types used to represent a WHERE clause). Implementations of ExecuteDsl and LoadQuery will generally require that this trait be implemented.

Required Methods§

Source

fn walk_ast<'b>(&'b self, pass: AstPass<'_, 'b, DB>) -> QueryResult<()>

Walk over this QueryFragment for all passes.

This method is where the actual behavior of an AST node is implemented. This method will contain the behavior required for all possible AST passes. See AstPass for more details.

Provided Methods§

Source

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

Available on crate feature i-implement-a-third-party-backend-and-opt-into-breaking-changes only.

Converts this QueryFragment to its SQL representation.

This method should only be called by implementations of Connection.

Source

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

Available on crate feature i-implement-a-third-party-backend-and-opt-into-breaking-changes only.

Serializes all bind parameters in this query.

A bind parameter is a value which is sent separately from the query itself. It is represented in SQL with a placeholder such as ? or $1.

This method should only be called by implementations of Connection.

Source

fn is_safe_to_cache_prepared(&self, backend: &DB) -> QueryResult<bool>

Available on crate feature i-implement-a-third-party-backend-and-opt-into-breaking-changes only.

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

In order to keep our prepared statement cache at a reasonable size, we avoid caching any queries which represent a potentially unbounded number of SQL queries. Generally this will only return true for queries for which to_sql will always construct exactly identical SQL.

Some examples of where this method will return false are:

SqlLiteral (We don’t know if the SQL was constructed dynamically, so we must assume that it was)
In and NotIn (Each value requires a separate bind param placeholder)

This method should only be called by implementations of Connection.

Source

fn is_noop(&self, backend: &DB) -> QueryResult<bool>

Available on crate feature i-implement-a-third-party-backend-and-opt-into-breaking-changes only.

Does walking this AST have any effect?

Trait QueryFragmentCopy item path

Required Methods§

fn walk_ast<'b>(&'b self, pass: AstPass<'_, 'b, DB>) -> QueryResult<()>

Provided Methods§

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

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

fn is_safe_to_cache_prepared(&self, backend: &DB) -> QueryResult<bool>

fn is_noop(&self, backend: &DB) -> QueryResult<bool>

Trait Implementations§

impl<DB> QueryId for dyn QueryFragment<DB>

const HAS_STATIC_QUERY_ID: bool = false

type QueryId = ()

fn query_id() -> Option<TypeId>

Implementations on Foreign Types§

impl<DB: Backend> QueryFragment<DB> for ()

fn walk_ast<'b>(&'b self, _: AstPass<'_, 'b, DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

impl<T0: QueryFragment<__DB>, T1: QueryFragment<__DB>, T2: QueryFragment<__DB>, T3: QueryFragment<__DB>, T4: QueryFragment<__DB>, T5: QueryFragment<__DB>, T6: QueryFragment<__DB>, T7: QueryFragment<__DB>, __DB: Backend> QueryFragment<__DB> for (T0, T1, T2, T3, T4, T5, T6, T7)

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

impl<T0: QueryFragment<__DB>, T1: QueryFragment<__DB>, T2: QueryFragment<__DB>, T3: QueryFragment<__DB>, T4: QueryFragment<__DB>, T5: QueryFragment<__DB>, T6: QueryFragment<__DB>, __DB: Backend> QueryFragment<__DB> for (T0, T1, T2, T3, T4, T5, T6)

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

impl<T0: QueryFragment<__DB>, T1: QueryFragment<__DB>, T2: QueryFragment<__DB>, T3: QueryFragment<__DB>, T4: QueryFragment<__DB>, T5: QueryFragment<__DB>, __DB: Backend> QueryFragment<__DB> for (T0, T1, T2, T3, T4, T5)

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

impl<T0: QueryFragment<__DB>, T1: QueryFragment<__DB>, T2: QueryFragment<__DB>, T3: QueryFragment<__DB>, T4: QueryFragment<__DB>, __DB: Backend> QueryFragment<__DB> for (T0, T1, T2, T3, T4)

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

impl<T0: QueryFragment<__DB>, T1: QueryFragment<__DB>, T2: QueryFragment<__DB>, T3: QueryFragment<__DB>, __DB: Backend> QueryFragment<__DB> for (T0, T1, T2, T3)

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

impl<T0: QueryFragment<__DB>, T1: QueryFragment<__DB>, T2: QueryFragment<__DB>, __DB: Backend> QueryFragment<__DB> for (T0, T1, T2)

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

impl<T0: QueryFragment<__DB>, T1: QueryFragment<__DB>, __DB: Backend> QueryFragment<__DB> for (T0, T1)

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

impl<T0: QueryFragment<__DB>, __DB: Backend> QueryFragment<__DB> for (T0,)

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, __DB>) -> QueryResult<()>

impl<T, DB> QueryFragment<DB> for Option<T>where DB: Backend, T: QueryFragment<DB>,

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

impl<T, DB> QueryFragment<DB> for &Twhere DB: Backend, T: QueryFragment<DB> + ?Sized,

fn walk_ast<'b>(&'b self, pass: AstPass<'_, 'b, DB>) -> QueryResult<()>

impl<T, DB> QueryFragment<DB> for Box<T>where DB: Backend, T: QueryFragment<DB> + ?Sized,

fn walk_ast<'b>(&'b self, pass: AstPass<'_, 'b, DB>) -> QueryResult<()>

Implementors§

impl QueryFragment<Mysql> for BoxedLimitOffsetClause<'_, Mysql>

impl QueryFragment<Mysql> for InsertOrIgnore

impl QueryFragment<Mysql> for LimitOffsetClause<NoLimitClause, NoOffsetClause>

impl QueryFragment<Mysql> for Replace

impl QueryFragment<Pg> for BoxedLimitOffsetClause<'_, Pg>

impl QueryFragment<Sqlite> for BoxedLimitOffsetClause<'_, Sqlite>

impl QueryFragment<Sqlite> for InsertOrIgnore

impl QueryFragment<Sqlite> for LimitOffsetClause<NoLimitClause, NoOffsetClause>

impl QueryFragment<Sqlite> for Replace

impl<'a, ST, QS, DB, GB> QueryFragment<DB, AnsiSqlSelectStatement> for BoxedSelectStatement<'a, ST, QS, DB, GB>where DB: Backend<SelectStatementSyntax = AnsiSqlSelectStatement> + DieselReserveSpecialization, QS: QueryFragment<DB>, BoxedLimitOffsetClause<'a, DB>: QueryFragment<DB>,

impl<C> QueryFragment<Pg> for TransactionBuilder<'_, C>

impl<DB> QueryFragment<DB> for Allwhere DB: Backend + DieselReserveSpecialization,

impl<DB> QueryFragment<DB> for Distinctwhere DB: Backend + DieselReserveSpecialization,

impl<DB> QueryFragment<DB> for Exceptwhere DB: Backend + DieselReserveSpecialization,

impl<DB> QueryFragment<DB> for Intersectwhere DB: Backend + DieselReserveSpecialization,

impl<DB> QueryFragment<DB> for NoFromClausewhere Self: QueryFragment<DB, DB::EmptyFromClauseSyntax>, DB: Backend,

impl<DB> QueryFragment<DB> for NoLimitClausewhere DB: Backend + DieselReserveSpecialization,

Trait QueryFragment

impl<T0: QueryFragment<DB>, T1: QueryFragment<DB>, T2: QueryFragment<DB>, T3: QueryFragment<DB>, T4: QueryFragment<DB>, T5: QueryFragment<DB>, T6: QueryFragment<DB>, T7: QueryFragment<DB>, DB: Backend> QueryFragment<DB> for (T0, T1, T2, T3, T4, T5, T6, T7)

impl<T0: QueryFragment<DB>, T1: QueryFragment<DB>, T2: QueryFragment<DB>, T3: QueryFragment<DB>, T4: QueryFragment<DB>, T5: QueryFragment<DB>, T6: QueryFragment<DB>, DB: Backend> QueryFragment<__DB> for (T0, T1, T2, T3, T4, T5, T6)

impl<T0: QueryFragment<DB>, T1: QueryFragment<DB>, T2: QueryFragment<DB>, T3: QueryFragment<DB>, T4: QueryFragment<DB>, T5: QueryFragment<DB>, DB: Backend> QueryFragment<DB> for (T0, T1, T2, T3, T4, T5)

impl<T0: QueryFragment<DB>, T1: QueryFragment<DB>, T2: QueryFragment<DB>, T3: QueryFragment<DB>, T4: QueryFragment<DB>, DB: Backend> QueryFragment<__DB> for (T0, T1, T2, T3, T4)

impl<T0: QueryFragment<DB>, T1: QueryFragment<DB>, T2: QueryFragment<DB>, T3: QueryFragment<DB>, DB: Backend> QueryFragment<DB> for (T0, T1, T2, T3)

impl<T0: QueryFragment<DB>, T1: QueryFragment<DB>, T2: QueryFragment<DB>, DB: Backend> QueryFragment<__DB> for (T0, T1, T2)

impl<T0: QueryFragment<DB>, T1: QueryFragment<DB>, DB: Backend> QueryFragment<DB> for (T0, T1)

impl<T0: QueryFragment<DB>, DB: Backend> QueryFragment<__DB> for (T0,)

impl<T, DB> QueryFragment<DB> for Option<T>
where DB: Backend, T: QueryFragment<DB>,

impl<T, DB> QueryFragment<DB> for &T
where DB: Backend, T: QueryFragment<DB> + ?Sized,

impl<T, DB> QueryFragment<DB> for Box<T>
where DB: Backend, T: QueryFragment<DB> + ?Sized,

impl<'a, ST, QS, DB, GB> QueryFragment<DB, AnsiSqlSelectStatement> for BoxedSelectStatement<'a, ST, QS, DB, GB>
where DB: Backend<SelectStatementSyntax = AnsiSqlSelectStatement> + DieselReserveSpecialization, QS: QueryFragment<DB>, BoxedLimitOffsetClause<'a, DB>: QueryFragment<DB>,

impl<DB> QueryFragment<DB> for All
where DB: Backend + DieselReserveSpecialization,

impl<DB> QueryFragment<DB> for Distinct
where DB: Backend + DieselReserveSpecialization,

impl<DB> QueryFragment<DB> for Except
where DB: Backend + DieselReserveSpecialization,

impl<DB> QueryFragment<DB> for Intersect
where DB: Backend + DieselReserveSpecialization,

impl<DB> QueryFragment<DB> for NoFromClause
where Self: QueryFragment<DB, DB::EmptyFromClauseSyntax>, DB: Backend,

impl<DB> QueryFragment<DB> for NoLimitClause
where DB: Backend + DieselReserveSpecialization,

impl<DB> QueryFragment<DB> for NoOffsetClause
where DB: Backend + DieselReserveSpecialization,

impl<DB> QueryFragment<DB> for NoOrderClause
where DB: Backend + DieselReserveSpecialization,

impl<DB> QueryFragment<DB> for Union
where DB: Backend + DieselReserveSpecialization,

impl<DB> QueryFragment<DB, AnsiSqlFromClauseSyntax> for NoFromClause
where DB: Backend<EmptyFromClauseSyntax = AnsiSqlFromClauseSyntax>,

impl<DB, Inner> QueryFragment<DB> for SqlQuery<Inner>
where DB: Backend + DieselReserveSpecialization, Inner: QueryFragment<DB>,

impl<DB, Query> QueryFragment<DB> for BoxedSqlQuery<'_, DB, Query>
where DB: Backend + DieselReserveSpecialization, Query: QueryFragment<DB>,

impl<DB, T> QueryFragment<DB> for CollectedQuery<T>
where DB: Backend + DieselReserveSpecialization, for<'a> <DB as Backend>::BindCollector<'a>: MoveableBindCollector<DB, BindData = T>,

impl<Expr, DB> QueryFragment<DB> for LimitClause<Expr>
where DB: Backend + DieselReserveSpecialization, Expr: QueryFragment<DB>,

impl<Expr, DB> QueryFragment<DB> for OffsetClause<Expr>
where DB: Backend + DieselReserveSpecialization, Expr: QueryFragment<DB>,

impl<Expr, DB> QueryFragment<DB> for OrderClause<Expr>
where DB: Backend + DieselReserveSpecialization, Expr: QueryFragment<DB>,

impl<Expr, DB> QueryFragment<DB> for ReturningClause<Expr>
where DB: Backend, Self: QueryFragment<DB, DB::ReturningClause>,

impl<Expr, DB> QueryFragment<DB, PgLikeReturningClause> for ReturningClause<Expr>
where DB: Backend<ReturningClause = PgLikeReturningClause>, Expr: QueryFragment<DB>,

impl<F, S, D, W, O, LOf, G, H, LC, DB> QueryFragment<DB> for SelectStatement<F, S, D, W, O, LOf, G, H, LC>
where DB: Backend, Self: QueryFragment<DB, DB::SelectStatementSyntax>,

impl<L> QueryFragment<Mysql> for LimitOffsetClause<LimitClause<L>, NoOffsetClause>
where LimitClause<L>: QueryFragment<Mysql>,

impl<L> QueryFragment<Sqlite> for LimitOffsetClause<LimitClause<L>, NoOffsetClause>
where LimitClause<L>: QueryFragment<Sqlite>,

impl<L, O> QueryFragment<Mysql> for LimitOffsetClause<LimitClause<L>, OffsetClause<O>>
where LimitClause<L>: QueryFragment<Mysql>, OffsetClause<O>: QueryFragment<Mysql>,

impl<L, O> QueryFragment<Pg> for LimitOffsetClause<L, O>
where L: QueryFragment<Pg>, O: QueryFragment<Pg>,

impl<L, O> QueryFragment<Sqlite> for LimitOffsetClause<LimitClause<L>, OffsetClause<O>>
where LimitClause<L>: QueryFragment<Sqlite>, OffsetClause<O>: QueryFragment<Sqlite>,

impl<L, R, DB> QueryFragment<DB> for Concat<L, R>
where DB: Backend, Self: QueryFragment<DB, DB::ConcatClause>,

impl<L, R, DB> QueryFragment<DB, ConcatWithPipesClause> for Concat<L, R>
where L: QueryFragment<DB>, R: QueryFragment<DB>, DB: Backend + SqlDialect<ConcatClause = ConcatWithPipesClause>,

impl<O> QueryFragment<Sqlite> for LimitOffsetClause<NoLimitClause, OffsetClause<O>>
where OffsetClause<O>: QueryFragment<Sqlite>,

impl<Query, Value, DB> QueryFragment<DB> for UncheckedBind<Query, Value>
where DB: Backend, Query: QueryFragment<DB>, Value: QueryFragment<DB>,

impl<S> QueryFragment<Pg> for Only<S>
where S: QueryFragment<Pg>,

impl<S, C, DB> QueryFragment<DB> for AliasedField<S, C>
where S: AliasSource, DB: Backend, C: Column<Table = S::Target>,

impl<S, DB> QueryFragment<DB> for Alias<S>
where S: AliasSource, DB: Backend, Self: QueryFragment<DB, DB::AliasSyntax>,

impl<S, DB> QueryFragment<DB, AsAliasSyntax> for Alias<S>
where S: AliasSource, DB: Backend, S::Target: QueryFragment<DB>,

impl<S, TSM> QueryFragment<Pg> for Tablesample<S, TSM>
where S: QueryFragment<Pg>, TSM: TablesampleMethod,

impl<ST, I, DB> QueryFragment<DB> for Many<ST, I>
where Self: QueryFragment<DB, DB::ArrayComparison>, DB: Backend,

impl<ST, I, DB> QueryFragment<DB, AnsiSqlArrayComparison> for Many<ST, I>
where DB: Backend + HasSqlType<ST> + SqlDialect<ArrayComparison = AnsiSqlArrayComparison>, ST: SingleValue, I: ToSql<ST, DB>,

impl<ST, QS, DB, GB> QueryFragment<DB> for BoxedSelectStatement<'_, ST, QS, DB, GB>
where DB: Backend, Self: QueryFragment<DB, DB::SelectStatementSyntax>,

impl<ST, T, DB> QueryFragment<DB> for SqlLiteral<ST, T>
where DB: Backend, T: QueryFragment<DB>,

impl<T> QueryFragment<Pg> for DistinctOnClause<T>
where T: QueryFragment<Pg>,

impl<T, DB> QueryFragment<DB> for Exists<T>
where DB: Backend, Self: QueryFragment<DB, DB::ExistsSyntax>,

impl<T, DB> QueryFragment<DB, AnsiSqlExistsSyntax> for Exists<T>
where DB: Backend + SqlDialect<ExistsSyntax = AnsiSqlExistsSyntax>, T: QueryFragment<DB>,

impl<T, Tab, DB> QueryFragment<DB> for ValuesClause<T, Tab>
where DB: Backend, Tab: Table, T: InsertValues<DB, Tab>, DefaultValues: QueryFragment<DB>,