1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330
use crate::backend::{Backend, DieselReserveSpecialization};
use crate::dsl::{Filter, IntoBoxed, OrFilter};
use crate::expression::{AppearsOnTable, SelectableExpression};
use crate::query_builder::returning_clause::*;
use crate::query_builder::where_clause::*;
use crate::query_builder::*;
use crate::query_dsl::methods::{BoxedDsl, FilterDsl, OrFilterDsl};
use crate::query_dsl::RunQueryDsl;
use crate::query_source::{QuerySource, Table};
use crate::result::QueryResult;
use super::from_clause::FromClause;
#[must_use = "Queries are only executed when calling `load`, `get_result` or similar."]
/// Represents a SQL `DELETE` statement.
///
/// The type parameters on this struct represent:
///
/// - `T`: The table we are deleting from.
/// - `U`: The `WHERE` clause of this query. The exact types used to represent
/// this are private, and you should not make any assumptions about them.
/// - `Ret`: The `RETURNING` clause of this query. The exact types used to
/// represent this are private. You can safely rely on the default type
/// representing the lack of a `RETURNING` clause.
pub struct DeleteStatement<T: QuerySource, U, Ret = NoReturningClause> {
from_clause: FromClause<T>,
where_clause: U,
returning: Ret,
}
impl<T, U, Ret> Clone for DeleteStatement<T, U, Ret>
where
T: QuerySource,
FromClause<T>: Clone,
U: Clone,
Ret: Clone,
{
fn clone(&self) -> Self {
Self {
from_clause: self.from_clause.clone(),
where_clause: self.where_clause.clone(),
returning: self.returning.clone(),
}
}
}
impl<T, U, Ret> std::fmt::Debug for DeleteStatement<T, U, Ret>
where
T: QuerySource,
FromClause<T>: std::fmt::Debug,
U: std::fmt::Debug,
Ret: std::fmt::Debug,
{
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
f.debug_struct("DeleteStatement")
.field("from_clause", &self.from_clause)
.field("where_clause", &self.where_clause)
.field("returning", &self.returning)
.finish()
}
}
impl<T, U, Ret> QueryId for DeleteStatement<T, U, Ret>
where
T: QuerySource + QueryId + 'static,
U: QueryId,
Ret: QueryId,
{
type QueryId = DeleteStatement<T, U::QueryId, Ret::QueryId>;
const HAS_STATIC_QUERY_ID: bool =
T::HAS_STATIC_QUERY_ID && U::HAS_STATIC_QUERY_ID && Ret::HAS_STATIC_QUERY_ID;
}
/// A `DELETE` statement with a boxed `WHERE` clause
pub type BoxedDeleteStatement<'a, DB, T, Ret = NoReturningClause> =
DeleteStatement<T, BoxedWhereClause<'a, DB>, Ret>;
impl<T: QuerySource, U> DeleteStatement<T, U, NoReturningClause> {
pub(crate) fn new(table: T, where_clause: U) -> Self {
DeleteStatement {
from_clause: FromClause::new(table),
where_clause,
returning: NoReturningClause,
}
}
/// 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
/// `delete(table.filter(x))` and `delete(table).filter(x)`.
///
/// # Example
///
/// ```rust
/// # include!("../../doctest_setup.rs");
/// #
/// # fn main() {
/// # use schema::users::dsl::*;
/// # let connection = &mut establish_connection();
/// let deleted_rows = diesel::delete(users)
/// .filter(name.eq("Sean"))
/// .execute(connection);
/// assert_eq!(Ok(1), deleted_rows);
///
/// let expected_names = vec!["Tess".to_string()];
/// let names = users.select(name).load(connection);
///
/// assert_eq!(Ok(expected_names), names);
/// # }
/// ```
pub fn filter<Predicate>(self, predicate: Predicate) -> Filter<Self, Predicate>
where
Self: FilterDsl<Predicate>,
{
FilterDsl::filter(self, predicate)
}
/// Adds to the `WHERE` clause of a query using `OR`
///
/// If there is already a `WHERE` clause, the result will be `(old OR new)`.
/// Calling `foo.filter(bar).or_filter(baz)`
/// is identical to `foo.filter(bar.or(baz))`.
/// However, the second form is much harder to do dynamically.
///
/// # Example
///
/// ```rust
/// # include!("../../doctest_setup.rs");
/// #
/// # fn main() {
/// # use schema::users::dsl::*;
/// # let connection = &mut establish_connection();
/// let deleted_rows = diesel::delete(users)
/// .filter(name.eq("Sean"))
/// .or_filter(name.eq("Tess"))
/// .execute(connection);
/// assert_eq!(Ok(2), deleted_rows);
///
/// let num_users = users.count().first(connection);
///
/// assert_eq!(Ok(0), num_users);
/// # }
/// ```
pub fn or_filter<Predicate>(self, predicate: Predicate) -> OrFilter<Self, Predicate>
where
Self: OrFilterDsl<Predicate>,
{
OrFilterDsl::or_filter(self, predicate)
}
/// Boxes the `WHERE` clause of this delete 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
///
/// ```rust
/// # include!("../../doctest_setup.rs");
/// #
/// # fn main() {
/// # run_test().unwrap();
/// # }
/// #
/// # fn run_test() -> QueryResult<()> {
/// # use std::collections::HashMap;
/// # use schema::users::dsl::*;
/// # let connection = &mut establish_connection();
/// # let mut params = HashMap::new();
/// # params.insert("sean_has_been_a_jerk", true);
/// let mut query = diesel::delete(users)
/// .into_boxed();
///
/// if params["sean_has_been_a_jerk"] {
/// query = query.filter(name.eq("Sean"));
/// }
///
/// let deleted_rows = query.execute(connection)?;
/// assert_eq!(1, deleted_rows);
///
/// let expected_names = vec!["Tess"];
/// let names = users.select(name).load::<String>(connection)?;
///
/// assert_eq!(expected_names, names);
/// # Ok(())
/// # }
/// ```
pub fn into_boxed<'a, DB>(self) -> IntoBoxed<'a, Self, DB>
where
DB: Backend,
Self: BoxedDsl<'a, DB>,
{
BoxedDsl::internal_into_boxed(self)
}
}
impl<T, U, Ret, Predicate> FilterDsl<Predicate> for DeleteStatement<T, U, Ret>
where
U: WhereAnd<Predicate>,
Predicate: AppearsOnTable<T>,
T: QuerySource,
{
type Output = DeleteStatement<T, U::Output, Ret>;
fn filter(self, predicate: Predicate) -> Self::Output {
DeleteStatement {
from_clause: self.from_clause,
where_clause: self.where_clause.and(predicate),
returning: self.returning,
}
}
}
impl<T, U, Ret, Predicate> OrFilterDsl<Predicate> for DeleteStatement<T, U, Ret>
where
T: QuerySource,
U: WhereOr<Predicate>,
Predicate: AppearsOnTable<T>,
{
type Output = DeleteStatement<T, U::Output, Ret>;
fn or_filter(self, predicate: Predicate) -> Self::Output {
DeleteStatement {
from_clause: self.from_clause,
where_clause: self.where_clause.or(predicate),
returning: self.returning,
}
}
}
impl<'a, T, U, Ret, DB> BoxedDsl<'a, DB> for DeleteStatement<T, U, Ret>
where
U: Into<BoxedWhereClause<'a, DB>>,
T: QuerySource,
{
type Output = BoxedDeleteStatement<'a, DB, T, Ret>;
fn internal_into_boxed(self) -> Self::Output {
DeleteStatement {
where_clause: self.where_clause.into(),
returning: self.returning,
from_clause: self.from_clause,
}
}
}
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>,
{
fn walk_ast<'b>(&'b self, mut out: AstPass<'_, 'b, DB>) -> QueryResult<()> {
out.push_sql("DELETE ");
self.from_clause.walk_ast(out.reborrow())?;
self.where_clause.walk_ast(out.reborrow())?;
self.returning.walk_ast(out.reborrow())?;
Ok(())
}
}
impl<T, U> AsQuery for DeleteStatement<T, U, NoReturningClause>
where
T: Table,
T::AllColumns: SelectableExpression<T>,
DeleteStatement<T, U, ReturningClause<T::AllColumns>>: Query,
{
type SqlType = <Self::Query as Query>::SqlType;
type Query = DeleteStatement<T, U, ReturningClause<T::AllColumns>>;
fn as_query(self) -> Self::Query {
self.returning(T::all_columns())
}
}
impl<T, U, Ret> Query for DeleteStatement<T, U, ReturningClause<Ret>>
where
T: Table,
Ret: SelectableExpression<T>,
{
type SqlType = Ret::SqlType;
}
impl<T, U, Ret, Conn> RunQueryDsl<Conn> for DeleteStatement<T, U, Ret> where T: QuerySource {}
impl<T: QuerySource, U> DeleteStatement<T, U, NoReturningClause> {
/// Specify what expression is returned after execution of the `delete`.
///
/// # Examples
///
/// ### Deleting a record:
///
/// ```rust
/// # include!("../../doctest_setup.rs");
/// #
/// # #[cfg(feature = "postgres")]
/// # fn main() {
/// # use schema::users::dsl::*;
/// # let connection = &mut establish_connection();
/// let deleted_name = diesel::delete(users.filter(name.eq("Sean")))
/// .returning(name)
/// .get_result(connection);
/// assert_eq!(Ok("Sean".to_string()), deleted_name);
/// # }
/// # #[cfg(not(feature = "postgres"))]
/// # fn main() {}
/// ```
pub fn returning<E>(self, returns: E) -> DeleteStatement<T, U, ReturningClause<E>>
where
E: SelectableExpression<T>,
DeleteStatement<T, U, ReturningClause<E>>: Query,
{
DeleteStatement {
where_clause: self.where_clause,
from_clause: self.from_clause,
returning: ReturningClause(returns),
}
}
}