Allow SqlFragmentExpression to have Type/type mapping

Closes dotnet#32969

src/EFCore.Relational/Query/ISqlExpressionFactory.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Diagnostics.CodeAnalysis;
-using System.Runtime.CompilerServices;
-using Microsoft.EntityFrameworkCore.Query.Internal;
 using Microsoft.EntityFrameworkCore.Query.SqlExpressions;
 
 namespace Microsoft.EntityFrameworkCore.Query;
@@ -454,6 +452,15 @@ public interface ISqlExpressionFactory
     /// <returns>An expression representing a constant in a SQL tree.</returns>
     SqlConstantExpression Constant(object? value, Type type, RelationalTypeMapping? typeMapping = null);
 
+    /// <summary>
+    ///     Creates a new <see cref="SqlFragmentExpression" /> which represents a SQL token.
+    /// </summary>
+    /// <param name="sql">A string token to print in SQL tree.</param>
+    /// <param name="type">The <see cref="Type" /> of the expression.</param>
+    /// <param name="typeMapping">The <see cref="RelationalTypeMapping" /> associated with the expression.</param>
+    /// <returns>An expression representing a SQL token.</returns>
+    SqlFragmentExpression Fragment(string sql, Type type, RelationalTypeMapping? typeMapping = null);
+
     /// <summary>
     ///     Creates a new <see cref="SqlFragmentExpression" /> which represents a SQL token.
     /// </summary>

src/EFCore.Relational/Query/SqlExpressionFactory.cs

@@ -64,7 +64,7 @@ public SqlExpressionFactory(SqlExpressionFactoryDependencies dependencies)
             ScalarSubqueryExpression e => e.ApplyTypeMapping(typeMapping),
             SqlBinaryExpression e => ApplyTypeMappingOnSqlBinary(e, typeMapping),
             SqlConstantExpression e => e.ApplyTypeMapping(typeMapping),
-            SqlFragmentExpression e => e,
+            SqlFragmentExpression e => e.ApplyTypeMapping(typeMapping),
             SqlFunctionExpression e => e.ApplyTypeMapping(typeMapping),
             SqlParameterExpression e => e.ApplyTypeMapping(typeMapping),
             SqlUnaryExpression e => ApplyTypeMappingOnSqlUnary(e, typeMapping),
@@ -688,6 +688,10 @@ public virtual InExpression In(SqlExpression item, SqlParameterExpression values
     public virtual LikeExpression Like(SqlExpression match, SqlExpression pattern, SqlExpression? escapeChar = null)
         => (LikeExpression)ApplyDefaultTypeMapping(new LikeExpression(match, pattern, escapeChar, null));
 
+    /// <inheritdoc />
+    public virtual SqlFragmentExpression Fragment(string sql, Type type, RelationalTypeMapping? typeMapping = null)
+        => new(sql, type, typeMapping);
+
     /// <inheritdoc />
     public virtual SqlFragmentExpression Fragment(string sql)
         => new(sql);

src/EFCore.Relational/Query/SqlExpressions/SqlFragmentExpression.cs

@@ -19,7 +19,18 @@ public class SqlFragmentExpression : SqlExpression
     /// </summary>
     /// <param name="sql">A string token to print in SQL tree.</param>
     public SqlFragmentExpression(string sql)
-        : base(typeof(string), null)
+        : this(sql, typeof(string), typeMapping: null)
+    {
+    }
+
+    /// <summary>
+    ///     Creates a new instance of the <see cref="SqlFragmentExpression" /> class.
+    /// </summary>
+    /// <param name="sql">A string token to print in SQL tree.</param>
+    /// <param name="type">The <see cref="Type" /> of the expression.</param>
+    /// <param name="typeMapping">The <see cref="RelationalTypeMapping" /> associated with the expression.</param>
+    public SqlFragmentExpression(string sql, Type type, RelationalTypeMapping? typeMapping = null)
+        : base(type, typeMapping)
     {
         Sql = sql;
     }
@@ -29,6 +40,14 @@ public SqlFragmentExpression(string sql)
     /// </summary>
     public virtual string Sql { get; }
 
+    /// <summary>
+    ///     Applies supplied type mapping to this expression.
+    /// </summary>
+    /// <param name="typeMapping">A relational type mapping to apply.</param>
+    /// <returns>A new expression which has supplied type mapping.</returns>
+    public virtual SqlFragmentExpression ApplyTypeMapping(RelationalTypeMapping? typeMapping)
+        => new(Sql, Type, typeMapping);
+
     /// <inheritdoc />
     protected override Expression VisitChildren(ExpressionVisitor visitor)
         => this;

src/EFCore/Query/ExpressionPrinter.cs

@@ -619,7 +619,7 @@ protected override Expression VisitMemberInit(MemberInitExpression memberInitExp
         _stringBuilder.Append("new " + memberInitExpression.Type.ShortDisplayName());
 
         var appendAction = memberInitExpression.Bindings.Count > 1 ? (Func<string, ExpressionVisitor>)AppendLine : Append;
-        appendAction("{ ");
+        appendAction(" { ");
         using (_stringBuilder.Indent())
         {
             for (var i = 0; i < memberInitExpression.Bindings.Count; i++)
@@ -790,7 +790,7 @@ protected override Expression VisitNew(NewExpression newExpression)
         }
         else
         {
-            appendAction("{ ");
+            appendAction(" { ");
         }
 
         IDisposable? indent = null;