Query: Add interface to get ITableBase for root level table sources

src/EFCore.Relational/Query/RelationalQueryableMethodTranslatingExpressionVisitor.cs

@@ -77,8 +77,7 @@ protected override Expression VisitExtension(Expression extensionExpression)
                     _sqlExpressionFactory.Select(
                         fromSqlQueryRootExpression.EntityType,
                         new FromSqlExpression(
-                            fromSqlQueryRootExpression.EntityType.GetDefaultMappings().Single().Table.Name[..1]
-                                .ToLowerInvariant(),
+                            fromSqlQueryRootExpression.EntityType.GetDefaultMappings().Single().Table,
                             fromSqlQueryRootExpression.Sql,
                             fromSqlQueryRootExpression.Argument)));
 
@@ -127,9 +126,14 @@ protected override Expression VisitExtension(Expression extensionExpression)
                 when queryRootExpression.GetType() == typeof(QueryRootExpression)
                 && queryRootExpression.EntityType.GetSqlQueryMappings().FirstOrDefault(m => m.IsDefaultSqlQueryMapping)?.SqlQuery is
                     ISqlQuery sqlQuery:
-                return Visit(
-                    new FromSqlQueryRootExpression(
-                        queryRootExpression.EntityType, sqlQuery.Sql, Expression.Constant(Array.Empty<object>(), typeof(object[]))));
+                return CreateShapedQueryExpression(
+                    queryRootExpression.EntityType,
+                    _sqlExpressionFactory.Select(
+                        queryRootExpression.EntityType,
+                        new FromSqlExpression(
+                            queryRootExpression.EntityType.GetDefaultMappings().Single().Table,
+                            sqlQuery.Sql,
+                            Expression.Constant(Array.Empty<object>(), typeof(object[])))));
 
             case GroupByShaperExpression groupByShaperExpression:
                 var groupShapedQueryExpression = groupByShaperExpression.GroupingEnumerable;

src/EFCore.Relational/Query/SqlExpressionFactory.cs

@@ -637,13 +637,7 @@ private void AddConditions(SelectExpression selectExpression, IEntityType entity
             return;
         }
 
-        var table = selectExpression.Tables[0] switch
-        {
-            TableExpression te => te.Table,
-            TableValuedFunctionExpression tvfe => tvfe.StoreFunction,
-            _ => entityType.GetDefaultMappings().Single().Table,
-        };
-
+        var table = ((ITableBasedExpression)selectExpression.Tables[0]).Table;
         if (table.IsOptional(entityType))
         {
             var entityProjectionExpression = GetMappedEntityProjectionExpression(selectExpression);

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

@@ -14,28 +14,40 @@ namespace Microsoft.EntityFrameworkCore.Query.SqlExpressions;
 ///         not used in application code.
 ///     </para>
 /// </summary>
-public class FromSqlExpression : TableExpressionBase, IClonableTableExpressionBase
+public class FromSqlExpression : TableExpressionBase, IClonableTableExpressionBase, ITableBasedExpression
 {
+    private readonly ITableBase _table;
+
     /// <summary>
     ///     Creates a new instance of the <see cref="FromSqlExpression" /> class.
     /// </summary>
-    /// <param name="alias">A string alias for the table source.</param>
+    /// <param name="defaultTableBase">A default table base associated with this table source.</param>
     /// <param name="sql">A user-provided custom SQL for the table source.</param>
     /// <param name="arguments">A user-provided parameters to pass to the custom SQL.</param>
-    public FromSqlExpression(string alias, string sql, Expression arguments)
-        : this(alias, sql, arguments, annotations: null)
+    public FromSqlExpression(ITableBase defaultTableBase, string sql, Expression arguments)
+        : this(defaultTableBase.Name[..1].ToLowerInvariant(), defaultTableBase, sql, arguments, annotations: null)
     {
-        Sql = sql;
-        Arguments = arguments;
     }
 
+    // See issue#21660/21627
+    ///// <summary>
+    /////     Creates a new instance of the <see cref="FromSqlExpression" /> class.
+    ///// </summary>
+    ///// <param name="sqlQuery">A sql query associated with this table source.</param>
+    //public FromSqlExpression(ISqlQuery sqlQuery)
+    //    : this(sqlQuery, sqlQuery.Sql, Constant(Array.Empty<object>(), typeof(object[])))
+    //{
+    //}
+
     private FromSqlExpression(
         string alias,
+        ITableBase tableBase,
         string sql,
         Expression arguments,
         IEnumerable<IAnnotation>? annotations)
         : base(alias, annotations)
     {
+        _table = tableBase;
         Sql = sql;
         Arguments = arguments;
     }
@@ -68,16 +80,19 @@ public override string? Alias
     /// <returns>This expression if no children changed, or an expression with the updated children.</returns>
     public virtual FromSqlExpression Update(Expression arguments)
         => arguments != Arguments
-            ? new FromSqlExpression(Alias, Sql, arguments)
+            ? new FromSqlExpression(Alias, _table, Sql, arguments, GetAnnotations())
             : this;
 
+    /// <inheritdoc />
+    ITableBase ITableBasedExpression.Table => _table;
+
     /// <inheritdoc />
     protected override Expression VisitChildren(ExpressionVisitor visitor)
         => this;
 
     /// <inheritdoc />
     public virtual TableExpressionBase Clone()
-        => new FromSqlExpression(Alias, Sql, Arguments, GetAnnotations());
+        => new FromSqlExpression(Alias, _table, Sql, Arguments, GetAnnotations());
 
     /// <inheritdoc />
     protected override void Print(ExpressionPrinter expressionPrinter)
@@ -95,6 +110,7 @@ public override bool Equals(object? obj)
 
     private bool Equals(FromSqlExpression fromSqlExpression)
         => base.Equals(fromSqlExpression)
+            && _table == fromSqlExpression._table
             && Sql == fromSqlExpression.Sql
             && ExpressionEqualityComparer.Instance.Equals(Arguments, fromSqlExpression.Arguments);
 

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

@@ -0,0 +1,21 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.EntityFrameworkCore.Query.SqlExpressions;
+
+/// <summary>
+///     <para>
+///         An interface that gives access to <see cref="ITableBase"/> associated with given table source.
+///     </para>
+///     <para>
+///         This type is typically used by database providers (and other extensions). It is generally
+///         not used in application code.
+///     </para>
+/// </summary>
+public interface ITableBasedExpression
+{
+    /// <summary>
+    ///     The <see cref="ITableBase"/> associated with given table source.
+    /// </summary>
+    ITableBase Table { get; }
+}

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

@@ -374,13 +374,7 @@ internal SelectExpression(IEntityType entityType, TableExpressionBase tableExpre
             throw new InvalidOperationException(RelationalStrings.SelectExpressionNonTphWithCustomTable(entityType.DisplayName()));
         }
 
-        var table = tableExpressionBase switch
-        {
-            TableExpression tableExpression => tableExpression.Table,
-            TableValuedFunctionExpression tableValuedFunctionExpression => tableValuedFunctionExpression.StoreFunction,
-            _ => entityType.GetDefaultMappings().Single().Table
-        };
-
+        var table = ((ITableBasedExpression)tableExpressionBase).Table;
         var tableReferenceExpression = new TableReferenceExpression(this, tableExpressionBase.Alias!);
         AddTable(tableExpressionBase, tableReferenceExpression);
 

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

@@ -13,7 +13,7 @@ namespace Microsoft.EntityFrameworkCore.Query.SqlExpressions;
 ///     application or database provider code. If this is a problem for your application or provider, then please file
 ///     an issue at <see href="https://github.com/dotnet/efcore">github.com/dotnet/efcore</see>.
 /// </remarks>
-public sealed class TableExpression : TableExpressionBase, IClonableTableExpressionBase
+public sealed class TableExpression : TableExpressionBase, IClonableTableExpressionBase, ITableBasedExpression
 {
     internal TableExpression(ITableBase table)
         : this(table, annotations: null)
@@ -28,6 +28,9 @@ private TableExpression(ITableBase table, IEnumerable<IAnnotation>? annotations)
         Table = table;
     }
 
+    /// <inheritdoc />
+    ITableBase ITableBasedExpression.Table => Table;
+
     /// <inheritdoc />
     protected override void Print(ExpressionPrinter expressionPrinter)
     {

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

@@ -14,7 +14,7 @@ namespace Microsoft.EntityFrameworkCore.Query.SqlExpressions;
 ///         not used in application code.
 ///     </para>
 /// </summary>
-public class TableValuedFunctionExpression : TableExpressionBase
+public class TableValuedFunctionExpression : TableExpressionBase, ITableBasedExpression
 {
     /// <summary>
     ///     Creates a new instance of the <see cref="TableValuedFunctionExpression" /> class.
@@ -61,6 +61,9 @@ public override string? Alias
     /// </summary>
     public virtual IReadOnlyList<SqlExpression> Arguments { get; }
 
+    /// <inheritdoc />
+    ITableBase ITableBasedExpression.Table => StoreFunction;
+
     /// <inheritdoc />
     protected override Expression VisitChildren(ExpressionVisitor visitor)
     {