#1696 fix (#1702)

* Test suit load environment variable from env files

* Added expr() and exprs() for QuerySelect trait and Minor typo fix

* fmt

* Added doc testing for the new functions

* Remove excess comment for doc test

Co-authored-by: Chris Tsang <chris.2y3@outlook.com>

* Remove excess comment for doc test

Co-authored-by: Chris Tsang <chris.2y3@outlook.com>

* updated doc tests to make example more realistic

* changed doc test again for more realistic query and added expr_as()

* aligned expr_as() alias input with column_as() input

* update doc test for expr_as() according to previous changes

---------

Co-authored-by: Billy Chan <ccw.billy.123@gmail.com>
Co-authored-by: Chris Tsang <chris.2y3@outlook.com>

build-tools/docker-create.sh

@@ -3,7 +3,7 @@
 # Delete all containers
 # $ docker rm -f $(docker ps -a -q)
 # 
-# Delete all volumns
+# Delete all volumes
 # $ docker volume rm $(docker volume ls -q)
 # 
 # Delete all images

src/query/helper.rs

@@ -4,7 +4,7 @@ use crate::{
 };
 use sea_query::{
     Alias, ConditionType, Expr, Iden, IntoCondition, IntoIden, LockType, SeaRc, SelectExpr,
-    SelectStatement, TableRef,
+    SelectStatement, SimpleExpr, TableRef,
 };
 pub use sea_query::{Condition, ConditionalStatement, DynIden, JoinType, Order, OrderedStatement};
 
@@ -446,6 +446,79 @@ pub trait QuerySelect: Sized {
         self.query().lock_exclusive();
         self
     }
+
+    /// Add an expression to the select expression list.
+    /// ```
+    /// use sea_orm::sea_query::Expr;
+    /// use sea_orm::{entity::*, tests_cfg::cake, DbBackend, QuerySelect, QueryTrait};
+    ///
+    /// assert_eq!(
+    ///     cake::Entity::find()
+    ///         .select_only()
+    ///         .expr(Expr::col((cake::Entity, cake::Column::Id)))
+    ///         .build(DbBackend::MySql)
+    ///         .to_string(),
+    ///     "SELECT `cake`.`id` FROM `cake`"
+    /// );
+    /// ```
+    fn expr<T>(mut self, expr: T) -> Self
+    where
+        T: Into<SelectExpr>,
+    {
+        self.query().expr(expr);
+        self
+    }
+
+    /// Add select expressions from vector of [`SelectExpr`].
+    /// ```
+    /// use sea_orm::sea_query::Expr;
+    /// use sea_orm::{entity::*, tests_cfg::cake, DbBackend, QuerySelect, QueryTrait};
+    ///
+    /// assert_eq!(
+    ///     cake::Entity::find()
+    ///         .select_only()
+    ///         .exprs([
+    ///             Expr::col((cake::Entity, cake::Column::Id)),
+    ///             Expr::col((cake::Entity, cake::Column::Name)),
+    ///         ])
+    ///         .build(DbBackend::MySql)
+    ///         .to_string(),
+    ///     "SELECT `cake`.`id`, `cake`.`name` FROM `cake`"
+    /// );
+    /// ```
+    fn exprs<T, I>(mut self, exprs: I) -> Self
+    where
+        T: Into<SelectExpr>,
+        I: IntoIterator<Item = T>,
+    {
+        self.query().exprs(exprs);
+        self
+    }
+
+    /// Select column.
+    /// ```
+    /// use sea_orm::sea_query::{Alias, Expr, Func};
+    /// use sea_orm::{entity::*, tests_cfg::cake, DbBackend, QuerySelect, QueryTrait};
+    ///
+    /// assert_eq!(
+    ///     cake::Entity::find()
+    ///         .expr_as(
+    ///             Func::upper(Expr::col((cake::Entity, cake::Column::Name))),
+    ///             "name_upper"
+    ///         )
+    ///         .build(DbBackend::MySql)
+    ///         .to_string(),
+    ///     "SELECT `cake`.`id`, `cake`.`name`, UPPER(`cake`.`name`) AS `name_upper` FROM `cake`"
+    /// );
+    /// ```
+    fn expr_as<T, A>(&mut self, expr: T, alias: A) -> &mut Self
+    where
+        T: Into<SimpleExpr>,
+        A: IntoIdentity,
+    {
+        self.query().expr_as(expr, alias.into_identity());
+        self
+    }
 }
 
 // LINT: when the column does not appear in tables selected from