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

pub mod changeset;
pub mod target;

pub use self::changeset::{Changeset, AsChangeset};
pub use self::target::{UpdateTarget, IntoUpdateTarget};

use backend::Backend;
use expression::{Expression, SelectableExpression, NonAggregate};
use query_builder::*;
use query_builder::returning_clause::*;
use query_source::Table;
use result::Error::QueryBuilderError;
use result::QueryResult;

/// The type returned by [`update`](/diesel/fn.update.html). The only thing you can do
/// with this type is call `set` on it.
#[derive(Debug)]
pub struct IncompleteUpdateStatement<T, U>(UpdateTarget<T, U>);

impl<T, U> IncompleteUpdateStatement<T, U> {
    #[doc(hidden)]
    pub fn new(t: UpdateTarget<T, U>) -> Self {
        IncompleteUpdateStatement(t)
    }
}

impl<T, U> IncompleteUpdateStatement<T, U> {
    pub fn set<V>(self, values: V) -> UpdateStatement<T, U, V::Changeset, NoReturningClause> where
        T: Table,
        V: changeset::AsChangeset<Target=T>,
        UpdateStatement<T, U, V::Changeset, NoReturningClause>: AsQuery,
    {
        UpdateStatement {
            table: self.0.table,
            where_clause: self.0.where_clause,
            values: values.as_changeset(),
            returning: NoReturningClause,
        }
    }
}

#[derive(Debug, Copy, Clone)]
pub struct UpdateStatement<T, U, V, Ret = NoReturningClause> {
    table: T,
    where_clause: U,
    values: V,
    returning: Ret,
}

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: changeset::Changeset<DB>,
    Ret: QueryFragment<DB>,
{
    fn walk_ast(&self, mut out: AstPass<DB>) -> QueryResult<()> {
        if self.values.is_noop() {
            return Err(QueryBuilderError(
                "There are no changes to save. This query cannot be built".into()
            ));
        }

        out.unsafe_to_cache_prepared();
        out.push_sql("UPDATE ");
        self.table.from_clause().walk_ast(out.reborrow())?;
        out.push_sql(" SET ");
        self.values.walk_ast(out.reborrow())?;
        self.where_clause.walk_ast(out.reborrow())?;
        self.returning.walk_ast(out.reborrow())?;
        Ok(())
    }
}

impl_query_id!(noop: UpdateStatement<T, U, V, Ret>);

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

    fn as_query(self) -> Self::Query {
        self.returning(T::all_columns())
    }
}

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;
}

impl<T, U, V> UpdateStatement<T, U, V, NoReturningClause> {
    /// Specify what expression is returned after execution of the `update`.
    /// # Examples
    ///
    /// ### Updating a single record:
    ///
    /// ```rust
    /// # #[macro_use] extern crate diesel;
    /// # include!("src/doctest_setup.rs");
    /// #
    /// # table! {
    /// #     users {
    /// #         id -> Integer,
    /// #         name -> VarChar,
    /// #     }
    /// # }
    /// #
    /// # #[cfg(feature = "postgres")]
    /// # fn main() {
    /// #     use self::users::dsl::*;
    /// #     let connection = establish_connection();
    /// 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);
    /// # }
    /// # #[cfg(not(feature = "postgres"))]
    /// # fn main() {}
    /// ```
    pub fn returning<E>(self, returns: E) -> UpdateStatement<T, U, V, ReturningClause<E>> where
        T: Table,
        UpdateStatement<T, U, V, ReturningClause<E>>: Query,
    {
        UpdateStatement {
            table: self.table,
            where_clause: self.where_clause,
            values: self.values,
            returning: ReturningClause(returns),
        }
    }
}