Implement LINQ LeftJoin and RightJoin (#110872)

Closes #110292
dotnet · Dec 23, 2024 · 9c1bae3 · 9c1bae3
1 parent 74bddba
commit 9c1bae3
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Showing 14 changed files with 1,685 additions and 3 deletions.
diff --git a/src/libraries/System.Linq.Queryable/ref/System.Linq.Queryable.cs b/src/libraries/System.Linq.Queryable/ref/System.Linq.Queryable.cs
@@ -123,6 +123,8 @@ public static partial class Queryable
         public static TSource LastOrDefault<TSource>(this System.Linq.IQueryable<TSource> source, TSource defaultValue) { throw null; }
         public static TSource Last<TSource>(this System.Linq.IQueryable<TSource> source) { throw null; }
         public static TSource Last<TSource>(this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<System.Func<TSource, bool>> predicate) { throw null; }
+        public static System.Linq.IQueryable<TResult> LeftJoin<TOuter, TInner, TKey, TResult>(this System.Linq.IQueryable<TOuter> outer, System.Collections.Generic.IEnumerable<TInner> inner, System.Linq.Expressions.Expression<System.Func<TOuter, TKey>> outerKeySelector, System.Linq.Expressions.Expression<System.Func<TInner, TKey>> innerKeySelector, System.Linq.Expressions.Expression<System.Func<TOuter, TInner?, TResult>> resultSelector) { throw null; }
+        public static System.Linq.IQueryable<TResult> LeftJoin<TOuter, TInner, TKey, TResult>(this System.Linq.IQueryable<TOuter> outer, System.Collections.Generic.IEnumerable<TInner> inner, System.Linq.Expressions.Expression<System.Func<TOuter, TKey>> outerKeySelector, System.Linq.Expressions.Expression<System.Func<TInner, TKey>> innerKeySelector, System.Linq.Expressions.Expression<System.Func<TOuter, TInner?, TResult>> resultSelector, System.Collections.Generic.IEqualityComparer<TKey>? comparer) { throw null; }
         public static long LongCount<TSource>(this System.Linq.IQueryable<TSource> source) { throw null; }
         public static long LongCount<TSource>(this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<System.Func<TSource, bool>> predicate) { throw null; }
         public static TSource? MaxBy<TSource, TKey>(this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<System.Func<TSource, TKey>> keySelector) { throw null; }
@@ -146,6 +148,8 @@ public static partial class Queryable
         public static System.Linq.IOrderedQueryable<T> Order<T>(this System.Linq.IQueryable<T> source, System.Collections.Generic.IComparer<T> comparer) { throw null; }
         public static System.Linq.IQueryable<TSource> Prepend<TSource>(this System.Linq.IQueryable<TSource> source, TSource element) { throw null; }
         public static System.Linq.IQueryable<TSource> Reverse<TSource>(this System.Linq.IQueryable<TSource> source) { throw null; }
+        public static System.Linq.IQueryable<TResult> RightJoin<TOuter, TInner, TKey, TResult>(this System.Linq.IQueryable<TOuter> outer, System.Collections.Generic.IEnumerable<TInner> inner, System.Linq.Expressions.Expression<System.Func<TOuter, TKey>> outerKeySelector, System.Linq.Expressions.Expression<System.Func<TInner, TKey>> innerKeySelector, System.Linq.Expressions.Expression<System.Func<TOuter?, TInner, TResult>> resultSelector) { throw null; }
+        public static System.Linq.IQueryable<TResult> RightJoin<TOuter, TInner, TKey, TResult>(this System.Linq.IQueryable<TOuter> outer, System.Collections.Generic.IEnumerable<TInner> inner, System.Linq.Expressions.Expression<System.Func<TOuter, TKey>> outerKeySelector, System.Linq.Expressions.Expression<System.Func<TInner, TKey>> innerKeySelector, System.Linq.Expressions.Expression<System.Func<TOuter?, TInner, TResult>> resultSelector, System.Collections.Generic.IEqualityComparer<TKey>? comparer) { throw null; }
         public static System.Linq.IQueryable<TResult> SelectMany<TSource, TResult>(this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<System.Func<TSource, System.Collections.Generic.IEnumerable<TResult>>> selector) { throw null; }
         public static System.Linq.IQueryable<TResult> SelectMany<TSource, TResult>(this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<System.Func<TSource, int, System.Collections.Generic.IEnumerable<TResult>>> selector) { throw null; }
         public static System.Linq.IQueryable<TResult> SelectMany<TSource, TCollection, TResult>(this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<System.Func<TSource, System.Collections.Generic.IEnumerable<TCollection>>> collectionSelector, System.Linq.Expressions.Expression<System.Func<TSource, TCollection, TResult>> resultSelector) { throw null; }

diff --git a/src/libraries/System.Linq.Queryable/src/System/Linq/Queryable.cs b/src/libraries/System.Linq.Queryable/src/System/Linq/Queryable.cs
@@ -242,6 +242,38 @@ public static IQueryable<TResult> GroupJoin<TOuter, TInner, TKey, TResult>(this
                     outer.Expression, GetSourceExpression(inner), Expression.Quote(outerKeySelector), Expression.Quote(innerKeySelector), Expression.Quote(resultSelector), Expression.Constant(comparer, typeof(IEqualityComparer<TKey>))));
         }
 
+        [DynamicDependency("LeftJoin`4", typeof(Enumerable))]
+        public static IQueryable<TResult> LeftJoin<TOuter, TInner, TKey, TResult>(this IQueryable<TOuter> outer, IEnumerable<TInner> inner, Expression<Func<TOuter, TKey>> outerKeySelector, Expression<Func<TInner, TKey>> innerKeySelector, Expression<Func<TOuter, TInner?, TResult>> resultSelector)
+        {
+            ArgumentNullException.ThrowIfNull(outer);
+            ArgumentNullException.ThrowIfNull(inner);
+            ArgumentNullException.ThrowIfNull(outerKeySelector);
+            ArgumentNullException.ThrowIfNull(innerKeySelector);
+            ArgumentNullException.ThrowIfNull(resultSelector);
+
+            return outer.Provider.CreateQuery<TResult>(
+                Expression.Call(
+                    null,
+                    new Func<IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter, TKey>>, Expression<Func<TInner, TKey>>, Expression<Func<TOuter, TInner?, TResult>>, IQueryable<TResult>>(LeftJoin).Method,
+                    outer.Expression, GetSourceExpression(inner), Expression.Quote(outerKeySelector), Expression.Quote(innerKeySelector), Expression.Quote(resultSelector)));
+        }
+
+        [DynamicDependency("LeftJoin`4", typeof(Enumerable))]
+        public static IQueryable<TResult> LeftJoin<TOuter, TInner, TKey, TResult>(this IQueryable<TOuter> outer, IEnumerable<TInner> inner, Expression<Func<TOuter, TKey>> outerKeySelector, Expression<Func<TInner, TKey>> innerKeySelector, Expression<Func<TOuter, TInner?, TResult>> resultSelector, IEqualityComparer<TKey>? comparer)
+        {
+            ArgumentNullException.ThrowIfNull(outer);
+            ArgumentNullException.ThrowIfNull(inner);
+            ArgumentNullException.ThrowIfNull(outerKeySelector);
+            ArgumentNullException.ThrowIfNull(innerKeySelector);
+            ArgumentNullException.ThrowIfNull(resultSelector);
+
+            return outer.Provider.CreateQuery<TResult>(
+                Expression.Call(
+                    null,
+                    new Func<IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter, TKey>>, Expression<Func<TInner, TKey>>, Expression<Func<TOuter, TInner?, TResult>>, IEqualityComparer<TKey>, IQueryable<TResult>>(LeftJoin).Method,
+                    outer.Expression, GetSourceExpression(inner), Expression.Quote(outerKeySelector), Expression.Quote(innerKeySelector), Expression.Quote(resultSelector), Expression.Constant(comparer, typeof(IEqualityComparer<TKey>))));
+        }
+
         /// <summary>
         /// Sorts the elements of a sequence in ascending order.
         /// </summary>
@@ -440,6 +472,38 @@ public static IOrderedQueryable<TSource> OrderByDescending<TSource, TKey>(this I
                     source.Expression, Expression.Quote(keySelector), Expression.Constant(comparer, typeof(IComparer<TKey>))));
         }
 
+        [DynamicDependency("RightJoin`4", typeof(Enumerable))]
+        public static IQueryable<TResult> RightJoin<TOuter, TInner, TKey, TResult>(this IQueryable<TOuter> outer, IEnumerable<TInner> inner, Expression<Func<TOuter, TKey>> outerKeySelector, Expression<Func<TInner, TKey>> innerKeySelector, Expression<Func<TOuter?, TInner, TResult>> resultSelector)
+        {
+            ArgumentNullException.ThrowIfNull(outer);
+            ArgumentNullException.ThrowIfNull(inner);
+            ArgumentNullException.ThrowIfNull(outerKeySelector);
+            ArgumentNullException.ThrowIfNull(innerKeySelector);
+            ArgumentNullException.ThrowIfNull(resultSelector);
+
+            return outer.Provider.CreateQuery<TResult>(
+                Expression.Call(
+                    null,
+                    new Func<IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter, TKey>>, Expression<Func<TInner, TKey>>, Expression<Func<TOuter?, TInner, TResult>>, IQueryable<TResult>>(RightJoin).Method,
+                    outer.Expression, GetSourceExpression(inner), Expression.Quote(outerKeySelector), Expression.Quote(innerKeySelector), Expression.Quote(resultSelector)));
+        }
+
+        [DynamicDependency("RightJoin`4", typeof(Enumerable))]
+        public static IQueryable<TResult> RightJoin<TOuter, TInner, TKey, TResult>(this IQueryable<TOuter> outer, IEnumerable<TInner> inner, Expression<Func<TOuter, TKey>> outerKeySelector, Expression<Func<TInner, TKey>> innerKeySelector, Expression<Func<TOuter?, TInner, TResult>> resultSelector, IEqualityComparer<TKey>? comparer)
+        {
+            ArgumentNullException.ThrowIfNull(outer);
+            ArgumentNullException.ThrowIfNull(inner);
+            ArgumentNullException.ThrowIfNull(outerKeySelector);
+            ArgumentNullException.ThrowIfNull(innerKeySelector);
+            ArgumentNullException.ThrowIfNull(resultSelector);
+
+            return outer.Provider.CreateQuery<TResult>(
+                Expression.Call(
+                    null,
+                    new Func<IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter, TKey>>, Expression<Func<TInner, TKey>>, Expression<Func<TOuter?, TInner, TResult>>, IEqualityComparer<TKey>, IQueryable<TResult>>(RightJoin).Method,
+                    outer.Expression, GetSourceExpression(inner), Expression.Quote(outerKeySelector), Expression.Quote(innerKeySelector), Expression.Quote(resultSelector), Expression.Constant(comparer, typeof(IEqualityComparer<TKey>))));
+        }
+
         [DynamicDependency("ThenBy`2", typeof(Enumerable))]
         public static IOrderedQueryable<TSource> ThenBy<TSource, TKey>(this IOrderedQueryable<TSource> source, Expression<Func<TSource, TKey>> keySelector)
         {

diff --git a/src/libraries/System.Linq.Queryable/tests/JoinTests.cs b/src/libraries/System.Linq.Queryable/tests/JoinTests.cs
@@ -243,8 +243,9 @@ public void ResultSelectorNullNoComparer()
         [Fact]
         public void SelectorsReturnNull()
         {
-            int?[] inner = { null, null, null };
             int?[] outer = { null, null };
+            int?[] inner = { null, null, null };
+
             Assert.Empty(outer.AsQueryable().Join(inner.AsQueryable(), e => e, e => e, (x, y) => x));
         }