Trait QueryFragment 

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> { ... }
}

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

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

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

Converts this QueryFragment to its SQL representation.

This method should only be called by implementations of Connection.

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

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.

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

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.

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

Does walking this AST have any effect?

Trait Implementations

impl<DB> QueryId for dyn QueryFragment<DB>

const HAS_STATIC_QUERY_ID: bool = false

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

type QueryId = ()

A type which uniquely represents Self in a SQL query.

fn query_id() -> Option<TypeId>

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

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementations on Foreign Types

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

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

impl<T, DB> QueryFragment<DB> for &T

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

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

impl<T, DB> QueryFragment<DB> for Arc<T>

where 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<()>

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 Rc<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>

Available on crate feature mysql_backend only.

impl QueryFragment<Mysql> for InsertOrIgnore

Available on crate feature mysql_backend only.

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

Available on crate feature mysql_backend only.

impl QueryFragment<Mysql> for Replace

Available on crate feature mysql_backend only.

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

Available on crate feature postgres_backend only.

impl QueryFragment<Pg> for C

Available on crate feature postgres_backend only.

impl QueryFragment<Pg> for Posix

Available on crate feature postgres_backend only.

impl QueryFragment<Sqlite> for Binary

Available on crate feature __sqlite-shared only.

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

Available on crate feature __sqlite-shared only.

impl QueryFragment<Sqlite> for InsertOrIgnore

Available on crate feature __sqlite-shared only.

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

Available on crate feature __sqlite-shared only.

impl QueryFragment<Sqlite> for NoCase

Available on crate feature __sqlite-shared only.

impl QueryFragment<Sqlite> for RTrim

Available on crate feature __sqlite-shared only.

impl QueryFragment<Sqlite> for Replace

Available on crate feature __sqlite-shared only.

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>

Available on crate feature postgres_backend only.

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<DB: Backend> QueryFragment<DB> for Custom

impl<DB: Backend> QueryFragment<DB> for now

impl<DB: Backend> QueryFragment<DB> for today

impl<DB> QueryFragment<DB, AnsiSqlFromClauseSyntax> for NoFromClause

where DB: Backend<EmptyFromClauseSyntax = AnsiSqlFromClauseSyntax>,

impl<DB> QueryFragment<DB, FrameExclusionSupport> for ExcludeCurrentRow

where DB: Backend<WindowFrameExclusionSupport = FrameExclusionSupport>,

impl<DB> QueryFragment<DB, FrameExclusionSupport> for ExcludeGroup

where DB: Backend<WindowFrameExclusionSupport = FrameExclusionSupport>,

impl<DB> QueryFragment<DB, FrameExclusionSupport> for ExcludeNoOthers

where DB: Backend<WindowFrameExclusionSupport = FrameExclusionSupport>,

impl<DB> QueryFragment<DB, FrameExclusionSupport> for ExcludeTies

where DB: Backend<WindowFrameExclusionSupport = FrameExclusionSupport>,

impl<DB> QueryFragment<DB, IsoGroupWindowFrameUnit> for Groups

where DB: Backend<WindowFrameClauseGroupSupport = IsoGroupWindowFrameUnit>,

impl<DB> QueryFragment<DB> for All

where DB: Backend + DieselReserveSpecialization,

impl<DB> QueryFragment<DB> for CurrentRow

where DB: Backend,

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 ExcludeCurrentRow

where DB: Backend, Self: QueryFragment<DB, DB::WindowFrameExclusionSupport>,

impl<DB> QueryFragment<DB> for ExcludeGroup

where DB: Backend, Self: QueryFragment<DB, DB::WindowFrameExclusionSupport>,

impl<DB> QueryFragment<DB> for ExcludeNoOthers

where DB: Backend, Self: QueryFragment<DB, DB::WindowFrameExclusionSupport>,

impl<DB> QueryFragment<DB> for ExcludeTies

where DB: Backend, Self: QueryFragment<DB, DB::WindowFrameExclusionSupport>,

impl<DB> QueryFragment<DB> for Groups

where DB: Backend, Self: QueryFragment<DB, DB::WindowFrameClauseGroupSupport>,

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 NoReturningClause

where DB: Backend + DieselReserveSpecialization,

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

impl<DB> QueryFragment<DB> for OffsetFollowing

where DB: Backend,

impl<DB> QueryFragment<DB> for OffsetPreceding

where DB: Backend,

impl<DB> QueryFragment<DB> for Range

where DB: Backend,

impl<DB> QueryFragment<DB> for Rows

where DB: Backend,

impl<DB> QueryFragment<DB> for UnboundedFollowing

where DB: Backend,

impl<DB> QueryFragment<DB> for UnboundedPreceding

where DB: Backend,

impl<DB> QueryFragment<DB> for Union

where DB: Backend + DieselReserveSpecialization,

impl<Expr, DB> QueryFragment<DB, PgLikeReturningClause> for ReturningClause<Expr>

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

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

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>,

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

impl<F, S, D, W, O, LOf, G, H, LC, DB> QueryFragment<DB, AnsiSqlSelectStatement> for SelectStatement<F, S, D, W, O, LOf, G, H, LC>

where DB: Backend<SelectStatementSyntax = AnsiSqlSelectStatement>, S: QueryFragment<DB>, F: QueryFragment<DB>, D: QueryFragment<DB>, W: QueryFragment<DB>, O: QueryFragment<DB>, LOf: QueryFragment<DB>, G: QueryFragment<DB>, H: QueryFragment<DB>, LC: 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, O> QueryFragment<Mysql> for LimitOffsetClause<LimitClause<L>, OffsetClause<O>>

where LimitClause<L>: QueryFragment<Mysql>, OffsetClause<O>: QueryFragment<Mysql>,

Available on crate feature mysql_backend only.

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

where L: QueryFragment<Pg>, O: QueryFragment<Pg>,

Available on crate feature postgres_backend only.

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

where LimitClause<L>: QueryFragment<Sqlite>, OffsetClause<O>: QueryFragment<Sqlite>,

Available on crate feature __sqlite-shared only.

impl<L, R, DB> QueryFragment<DB, ConcatWithPipesClause> for Concat<L, R>

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

impl<L, R, DB> QueryFragment<DB> for Concat<L, R>

where DB: Backend, Self: QueryFragment<DB, DB::ConcatClause>,

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

where LimitClause<L>: QueryFragment<Mysql>,

Available on crate feature mysql_backend only.

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

where LimitClause<L>: QueryFragment<Sqlite>,

Available on crate feature __sqlite-shared only.

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

where OffsetClause<O>: QueryFragment<Sqlite>,

Available on crate feature __sqlite-shared only.

impl<Query, Value, DB> QueryFragment<DB> for UncheckedBind<Query, Value>

where DB: Backend, Query: QueryFragment<DB>, Value: QueryFragment<DB>,

impl<S, C, DB> QueryFragment<DB> for AliasedField<S, C>

where S: AliasSource, DB: Backend, C: QueryRelationField<QueryRelation = S::Target>,

impl<S, DB> QueryFragment<DB, AsAliasSyntax> for Alias<S>

where S: AliasSource, DB: Backend, S::Target: QueryFragment<DB>,

impl<S, DB> QueryFragment<DB> for Alias<S>

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

impl<S, TSM> QueryFragment<Pg> for Tablesample<S, TSM>

where S: QueryFragment<Pg>, TSM: TablesampleMethod,

Available on crate feature postgres_backend only.

impl<S> QueryFragment<Pg> for Only<S>

where S: QueryFragment<Pg>,

Available on crate feature postgres_backend only.

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>,

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

impl<ST, I, DB> QueryFragment<DB> for Many<ST, I>

where Self: QueryFragment<DB, DB::ArrayComparison>, DB: Backend,

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

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, C, DB> QueryFragment<DB> for Collate<T, C>

where DB: Backend, T: QueryFragment<DB>, C: QueryFragment<DB>,

impl<T, DB> QueryFragment<DB, AnsiSqlExistsSyntax> for Exists<T>

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

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

impl<T, DB> QueryFragment<DB> for Exists<T>

where DB: Backend, Self: QueryFragment<DB, DB::ExistsSyntax>,

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

impl<T, Tab, DB> QueryFragment<DB> for ValuesClause<T, Tab>

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

impl<T, U, DB> QueryFragment<DB, AnsiSqlArrayComparison> for In<T, U>

where DB: Backend + SqlDialect<ArrayComparison = AnsiSqlArrayComparison>, T: QueryFragment<DB>, U: QueryFragment<DB> + InExpression,

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

impl<T, U, DB> QueryFragment<DB, AnsiSqlArrayComparison> for NotIn<T, U>

where DB: Backend + SqlDialect<ArrayComparison = AnsiSqlArrayComparison>, T: QueryFragment<DB>, U: QueryFragment<DB> + InExpression,

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

impl<T, U, DB> QueryFragment<DB> for In<T, U>

where DB: Backend, Self: QueryFragment<DB, DB::ArrayComparison>,

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

impl<T, U, DB> QueryFragment<DB> for NotIn<T, U>

where DB: Backend, Self: QueryFragment<DB, DB::ArrayComparison>,

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

impl<T, U, Op, Ret, DB> QueryFragment<DB> for InsertStatement<T, U, Op, Ret>

where DB: Backend + DieselReserveSpecialization, T: Table, T::FromClause: QueryFragment<DB>, U: QueryFragment<DB> + CanInsertInSingleQuery<DB>, Op: QueryFragment<DB>, Ret: QueryFragment<DB>,

impl<T, U, Ret, DB> QueryFragment<DB> for DeleteStatement<T, U, Ret>

where DB: Backend + DieselReserveSpecialization, T: Table, FromClause<T>: QueryFragment<DB>, U: QueryFragment<DB>, Ret: QueryFragment<DB>,

impl<T, U, V, Ret, DB> QueryFragment<DB> for UpdateStatement<T, U, V, Ret>

where DB: Backend + DieselReserveSpecialization, T: Table, T::FromClause: QueryFragment<DB>, U: QueryFragment<DB>, V: QueryFragment<DB>, Ret: QueryFragment<DB>,

impl<T: QueryFragment<Mysql>> QueryFragment<Mysql> for ParenthesisWrapper<T>

Available on crate feature mysql_backend only.

impl<T: QueryFragment<Pg>> QueryFragment<Pg> for ParenthesisWrapper<T>

Available on crate feature postgres_backend only.

impl<T: QueryFragment<Sqlite>> QueryFragment<Sqlite> for ParenthesisWrapper<T>

Available on crate feature __sqlite-shared only.

impl<T> QueryFragment<Pg> for DistinctOnClause<T>

where T: QueryFragment<Pg>,

Available on crate feature postgres_backend only.

impl<Tab, DB, V, QId, const HAS_STATIC_QUERY_ID: bool> QueryFragment<DB, PostgresLikeBatchInsertSupport> for BatchInsert<Vec<ValuesClause<V, Tab>>, Tab, QId, HAS_STATIC_QUERY_ID>

where DB: Backend + SqlDialect<BatchInsertSupport = PostgresLikeBatchInsertSupport>, DB::InsertWithDefaultKeyword: SupportsDefaultKeyword, ValuesClause<V, Tab>: QueryFragment<DB>, V: QueryFragment<DB>,

impl<Tab, DB, V, QId, const HAS_STATIC_QUERY_ID: bool> QueryFragment<DB> for BatchInsert<V, Tab, QId, HAS_STATIC_QUERY_ID>

where DB: Backend, Self: QueryFragment<DB, DB::BatchInsertSupport>,

impl<Whens, E, DB> QueryFragment<DB> for CaseWhen<Whens, E>

where DB: Backend, Whens: QueryFragment<DB>, E: QueryFragment<DB>,