Experimental support for the Azure SQL json type

Fixes #28452
Fixes #32150

Remaining work:

- Test reverse engineering from an existing database
- Output a warning when the native JSON type is used
- Replace the ToJson overload with HasColumnType()
- Move the type mapping visitation to another visitor

Known issues:

- Various issues communicated with the SQL team--see TODO:SQLJSON
- Testing is disabled until we have an appropriate server and driver to test against

Author: ajcvickers

NuGet.config

@@ -2,6 +2,7 @@
 <configuration>
   <packageSources>
     <clear />
+    <add key="localnuget" value="C:\tempnuget" />
     <!--Begin: Package sources managed by Dependency Flow automation. Do not edit the sources below.-->
     <!--  Begin: Package sources from dotnet-runtime -->
     <!--  End: Package sources from dotnet-runtime -->

src/EFCore.Relational/Extensions/RelationalEntityTypeExtensions.cs

@@ -1610,6 +1610,46 @@ public static void SetContainerColumnName(this IMutableEntityType entityType, st
             ? columnName
             : (entityType.FindOwnership()?.PrincipalEntityType.GetContainerColumnName());
 
+    /// <summary>
+    ///     Sets the column type to use for the container column to which the entity type is mapped.
+    /// </summary>
+    /// <param name="entityType">The entity type.</param>
+    /// <param name="columnType">The database column type.</param>
+    public static void SetContainerColumnType(this IMutableEntityType entityType, string? columnType)
+        => entityType.SetOrRemoveAnnotation(RelationalAnnotationNames.ContainerColumnType, columnType);
+
+    /// <summary>
+    ///     Sets the column type to use for the container column to which the entity type is mapped.
+    /// </summary>
+    /// <param name="entityType">The entity type.</param>
+    /// <param name="columnType">The database column type.</param>
+    /// <param name="fromDataAnnotation">Indicates whether the configuration was specified using a data annotation.</param>
+    /// <returns>The configured value.</returns>
+    public static string? SetContainerColumnType(
+        this IConventionEntityType entityType,
+        string? columnType,
+        bool fromDataAnnotation = false)
+        => (string?)entityType.SetAnnotation(RelationalAnnotationNames.ContainerColumnType, columnType, fromDataAnnotation)?.Value;
+
+    /// <summary>
+    ///     Gets the <see cref="ConfigurationSource" /> for the container column type.
+    /// </summary>
+    /// <param name="entityType">The entity type.</param>
+    /// <returns>The <see cref="ConfigurationSource" />.</returns>
+    public static ConfigurationSource? GetContainerColumnTypeConfigurationSource(this IConventionEntityType entityType)
+        => entityType.FindAnnotation(RelationalAnnotationNames.ContainerColumnType)
+            ?.GetConfigurationSource();
+
+    /// <summary>
+    ///     Gets the column type to use for the container column to which the entity type is mapped.
+    /// </summary>
+    /// <param name="entityType">The entity type.</param>
+    /// <returns>The database column type.</returns>
+    public static string? GetContainerColumnType(this IReadOnlyEntityType entityType)
+        => entityType.FindAnnotation(RelationalAnnotationNames.ContainerColumnType)?.Value is string columnType
+            ? columnType
+            : (entityType.FindOwnership()?.PrincipalEntityType.GetContainerColumnType());
+
     /// <summary>
     ///     Sets the type mapping for the container column to which the entity type is mapped.
     /// </summary>

src/EFCore.Relational/Extensions/RelationalOwnedNavigationBuilderExtensions.cs

@@ -23,12 +23,7 @@ public static class RelationalOwnedNavigationBuilderExtensions
     /// <param name="builder">The builder for the owned navigation being configured.</param>
     /// <returns>The same builder instance so that multiple calls can be chained.</returns>
     public static OwnedNavigationBuilder ToJson(this OwnedNavigationBuilder builder)
-    {
-        var navigationName = builder.Metadata.GetNavigation(pointsToPrincipal: false)!.Name;
-        builder.ToJson(navigationName);
-
-        return builder;
-    }
+        => builder.ToJson(builder.Metadata.GetNavigation(pointsToPrincipal: false)!.Name);
 
     /// <summary>
     ///     Configures a relationship where this entity type and the entities that it owns are mapped to a JSON column in the database.
@@ -45,12 +40,7 @@ public static OwnedNavigationBuilder<TOwnerEntity, TDependentEntity> ToJson<TOwn
         this OwnedNavigationBuilder<TOwnerEntity, TDependentEntity> builder)
         where TOwnerEntity : class
         where TDependentEntity : class
-    {
-        var navigationName = builder.Metadata.GetNavigation(pointsToPrincipal: false)!.Name;
-        builder.ToJson(navigationName);
-
-        return builder;
-    }
+        => (OwnedNavigationBuilder<TOwnerEntity, TDependentEntity>)((OwnedNavigationBuilder)builder).ToJson();
 
     /// <summary>
     ///     Configures a relationship where this entity type and the entities that it owns are mapped to a JSON column in the database.
@@ -68,11 +58,7 @@ public static OwnedNavigationBuilder<TOwnerEntity, TDependentEntity> ToJson<TOwn
         string? jsonColumnName)
         where TOwnerEntity : class
         where TDependentEntity : class
-    {
-        builder.OwnedEntityType.SetContainerColumnName(jsonColumnName);
-
-        return builder;
-    }
+        => builder.ToJson(jsonColumnName, null);
 
     /// <summary>
     ///     Configures a relationship where this entity type and the entities that it owns are mapped to a JSON column in the database.
@@ -88,8 +74,47 @@ public static OwnedNavigationBuilder<TOwnerEntity, TDependentEntity> ToJson<TOwn
     public static OwnedNavigationBuilder ToJson(
         this OwnedNavigationBuilder builder,
         string? jsonColumnName)
+        => builder.ToJson(jsonColumnName, null);
+
+    /// <summary>
+    ///     Configures a relationship where this entity type and the entities that it owns are mapped to a JSON column in the database.
+    /// </summary>
+    /// <remarks>
+    ///     This method should only be specified for the outer-most owned entity in the given ownership structure.
+    ///     All entities owned by this will be automatically mapped to the same JSON column.
+    ///     The ownerships must still be explicitly defined.
+    /// </remarks>
+    /// <param name="builder">The builder for the owned navigation being configured.</param>
+    /// <param name="jsonColumnName">JSON column name to use.</param>
+    /// <param name="jsonColumnType">The database type for the JSON column, or <see langword="null"/> to use the database default.</param>
+    /// <returns>The same builder instance so that multiple calls can be chained.</returns>
+    public static OwnedNavigationBuilder<TOwnerEntity, TDependentEntity> ToJson<TOwnerEntity, TDependentEntity>(
+        this OwnedNavigationBuilder<TOwnerEntity, TDependentEntity> builder,
+        string? jsonColumnName,
+        string? jsonColumnType)
+        where TOwnerEntity : class
+        where TDependentEntity : class
+        => (OwnedNavigationBuilder<TOwnerEntity, TDependentEntity>)((OwnedNavigationBuilder)builder).ToJson(jsonColumnName, jsonColumnType);
+
+    /// <summary>
+    ///     Configures a relationship where this entity type and the entities that it owns are mapped to a JSON column in the database.
+    /// </summary>
+    /// <remarks>
+    ///     This method should only be specified for the outer-most owned entity in the given ownership structure.
+    ///     All entities owned by this will be automatically mapped to the same JSON column.
+    ///     The ownerships must still be explicitly defined.
+    /// </remarks>
+    /// <param name="builder">The builder for the owned navigation being configured.</param>
+    /// <param name="jsonColumnName">JSON column name to use.</param>
+    /// <param name="jsonColumnType">The database type for the JSON column, or <see langword="null"/> to use the database default.</param>
+    /// <returns>The same builder instance so that multiple calls can be chained.</returns>
+    public static OwnedNavigationBuilder ToJson(
+        this OwnedNavigationBuilder builder,
+        string? jsonColumnName,
+        string? jsonColumnType)
     {
         builder.OwnedEntityType.SetContainerColumnName(jsonColumnName);
+        builder.OwnedEntityType.SetContainerColumnType(jsonColumnType);
 
         return builder;
     }

src/EFCore.Relational/Extensions/RelationalTypeBaseExtensions.cs

@@ -368,6 +368,17 @@ public static bool IsMappedToJson(this IReadOnlyTypeBase typeBase)
             ? entityType.GetContainerColumnName()
             : ((IReadOnlyComplexType)typeBase).GetContainerColumnName();
 
+
+    /// <summary>
+    ///     Gets the column type to use for the container column to which the type is mapped.
+    /// </summary>
+    /// <param name="typeBase">The type.</param>
+    /// <returns>The database column type.</returns>
+    public static string? GetContainerColumnType(this IReadOnlyTypeBase typeBase)
+        => typeBase is IReadOnlyEntityType entityType
+            ? entityType.GetContainerColumnType()
+            : null;
+
     /// <summary>
     ///     Gets the value of JSON property name used for the given entity mapped to a JSON column.
     /// </summary>

src/EFCore.Relational/Metadata/Internal/RelationalModel.cs

@@ -286,12 +286,14 @@ private static void AddDefaultMappings(
                 includesDerivedTypes: entityType.GetDirectlyDerivedTypes().Any()
                     ? !isTpc && mappedType == entityType
                     : null);
+
             var containerColumnName = mappedType.GetContainerColumnName();
+            var containerColumnType = mappedType.GetContainerColumnType();
             if (!string.IsNullOrEmpty(containerColumnName))
             {
                 CreateContainerColumn(
-                    defaultTable, containerColumnName, mappedType, relationalTypeMappingSource,
-                    static (c, t, m) => new JsonColumnBase(c, m.StoreType, t, m));
+                    defaultTable, containerColumnName, containerColumnType, mappedType, relationalTypeMappingSource,
+                    static (colName, colType, table, mapping) => new JsonColumnBase(colName, colType ?? mapping.StoreType, table, mapping));
             }
             else
             {
@@ -492,11 +494,12 @@ private static void CreateTableMapping(
         };
 
         var containerColumnName = mappedType.GetContainerColumnName();
+        var containerColumnType = mappedType.GetContainerColumnType();
         if (!string.IsNullOrEmpty(containerColumnName))
         {
             CreateContainerColumn(
-                table, containerColumnName, (IEntityType)mappedType, relationalTypeMappingSource,
-                static (c, t, m) => new JsonColumn(c, m.StoreType, (Table)t, m));
+                table, containerColumnName, containerColumnType, (IEntityType)mappedType, relationalTypeMappingSource,
+                static (colName, colType, table, mapping) => new JsonColumn(colName, colType ?? mapping.StoreType, (Table)table, mapping));
         }
         else
         {
@@ -567,18 +570,19 @@ private static void CreateTableMapping(
     private static void CreateContainerColumn<TColumnMappingBase>(
         TableBase tableBase,
         string containerColumnName,
+        string? containerColumnType,
         IEntityType mappedType,
         IRelationalTypeMappingSource relationalTypeMappingSource,
-        Func<string, TableBase, RelationalTypeMapping, ColumnBase<TColumnMappingBase>> createColumn)
+        Func<string, string?, TableBase, RelationalTypeMapping, ColumnBase<TColumnMappingBase>> createColumn)
         where TColumnMappingBase : class, IColumnMappingBase
     {
         var ownership = mappedType.GetForeignKeys().Single(fk => fk.IsOwnership);
         if (!ownership.PrincipalEntityType.IsMappedToJson())
         {
             Check.DebugAssert(tableBase.FindColumn(containerColumnName) == null, $"Table does not have column '{containerColumnName}'.");
 
-            var jsonColumnTypeMapping = relationalTypeMappingSource.FindMapping(typeof(JsonElement), mappedType.Model)!;
-            var jsonColumn = createColumn(containerColumnName, tableBase, jsonColumnTypeMapping);
+            var jsonColumnTypeMapping = relationalTypeMappingSource.FindMapping(typeof(JsonElement), storeTypeName: containerColumnType)!;
+            var jsonColumn = createColumn(containerColumnName, containerColumnType, tableBase, jsonColumnTypeMapping);
             tableBase.Columns.Add(containerColumnName, jsonColumn);
             jsonColumn.IsNullable = !ownership.IsRequiredDependent || !ownership.IsUnique;
 
@@ -684,11 +688,12 @@ private static void CreateViewMapping(
         };
 
         var containerColumnName = mappedType.GetContainerColumnName();
+        var containerColumnType = mappedType.GetContainerColumnType();
         if (!string.IsNullOrEmpty(containerColumnName))
         {
             CreateContainerColumn(
-                view, containerColumnName, mappedType, relationalTypeMappingSource,
-                static (c, t, m) => new JsonViewColumn(c, m.StoreType, (View)t, m));
+                view, containerColumnName, containerColumnType, mappedType, relationalTypeMappingSource,
+                static (colName, colType, table, mapping) => new JsonViewColumn(colName, colType ?? mapping.StoreType, (View)table, mapping));
         }
         else
         {

src/EFCore.Relational/Metadata/RelationalAnnotationNames.cs

@@ -324,6 +324,11 @@ public static class RelationalAnnotationNames
     /// </summary>
     public const string ContainerColumnName = Prefix + "ContainerColumnName";
 
+    /// <summary>
+    ///     The column type for the container column to which the object is mapped.
+    /// </summary>
+    public const string ContainerColumnType = Prefix + nameof(ContainerColumnType);
+
     /// <summary>
     ///     The name for the annotation specifying container column type mapping.
     /// </summary>

src/EFCore.SqlServer/EFCore.SqlServer.csproj

@@ -41,6 +41,7 @@
 
   <ItemGroup>
     <Compile Include="..\Shared\*.cs" />
+    <Compile Remove="Storage\Internal\SqlServerJsonTypeMapping.cs" />
   </ItemGroup>
 
   <ItemGroup>
@@ -49,7 +50,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.Data.SqlClient" Version="5.2.1" />
+    <PackageReference Include="Microsoft.Data.SqlClient" Version="6.0.0-dev" />
   </ItemGroup>
 
   <ItemGroup>

src/EFCore.SqlServer/Query/Internal/SqlExpressions/SqlServerOpenJsonExpression.cs

@@ -321,4 +321,14 @@ public readonly record struct ColumnInfo(
         RelationalTypeMapping TypeMapping,
         IReadOnlyList<PathSegment>? Path = null,
         bool AsJson = false);
+
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    public virtual SqlServerOpenJsonExpression Update(SqlExpression sqlExpression)
+        => new(Alias, sqlExpression, Path, ColumnInfos);
+
 }

src/EFCore.SqlServer/Query/Internal/SqlServerQuerySqlGenerator.cs

@@ -475,7 +475,7 @@ protected override Expression VisitJsonScalar(JsonScalarExpression jsonScalarExp
             return jsonScalarExpression;
         }
 
-        if (jsonScalarExpression.TypeMapping is SqlServerJsonTypeMapping
+        if (jsonScalarExpression.TypeMapping is SqlServerJsonElementTypeMapping
             || jsonScalarExpression.TypeMapping?.ElementTypeMapping is not null)
         {
             Sql.Append("JSON_QUERY(");
@@ -494,7 +494,7 @@ protected override Expression VisitJsonScalar(JsonScalarExpression jsonScalarExp
         GenerateJsonPath(jsonScalarExpression.Path);
         Sql.Append(")");
 
-        if (jsonScalarExpression.TypeMapping is not SqlServerJsonTypeMapping and not StringTypeMapping)
+        if (jsonScalarExpression.TypeMapping is not SqlServerJsonElementTypeMapping and not StringTypeMapping)
         {
             Sql.Append(" AS ");
             Sql.Append(jsonScalarExpression.TypeMapping!.StoreType);

src/EFCore.SqlServer/Query/Internal/SqlServerTypeMappingPostprocessor.cs

@@ -43,8 +43,7 @@ protected override Expression VisitExtension(Expression expression)
         => expression switch
         {
             SqlServerOpenJsonExpression openJsonExpression
-                when TryGetInferredTypeMapping(openJsonExpression.Alias, "value", out var typeMapping)
-                => ApplyTypeMappingsOnOpenJsonExpression(openJsonExpression, new[] { typeMapping }),
+                => ApplyTypeMappingsOnOpenJsonExpression(openJsonExpression),
 
             _ => base.VisitExtension(expression)
         };
@@ -55,12 +54,21 @@ when TryGetInferredTypeMapping(openJsonExpression.Alias, "value", out var typeMa
     ///     any release. You should only use it directly in your code with extreme caution and knowing that
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
-    protected virtual SqlServerOpenJsonExpression ApplyTypeMappingsOnOpenJsonExpression(
-        SqlServerOpenJsonExpression openJsonExpression,
-        IReadOnlyList<RelationalTypeMapping> typeMappings)
+    protected virtual SqlServerOpenJsonExpression ApplyTypeMappingsOnOpenJsonExpression(SqlServerOpenJsonExpression openJsonExpression)
     {
-        Check.DebugAssert(typeMappings.Count == 1, "typeMappings.Count == 1");
-        var elementTypeMapping = typeMappings[0];
+        if (openJsonExpression is { JsonExpression.TypeMapping: SqlServerStringTypeMapping { StoreType: "json" } } or
+            { JsonExpression.TypeMapping: SqlServerJsonElementTypeMapping { StoreType: "json" } })
+        {
+            openJsonExpression = openJsonExpression.Update(
+                new SqlUnaryExpression(
+                    ExpressionType.Convert, (SqlExpression)Visit(openJsonExpression.JsonExpression), typeof(string),
+                    _typeMappingSource.FindMapping(typeof(string))!));
+        }
+
+        if (!TryGetInferredTypeMapping(openJsonExpression.Alias, "value", out var elementTypeMapping))
+        {
+            return openJsonExpression;
+        }
 
         // Constant queryables are translated to VALUES, no need for JSON.
         // Column queryables have their type mapping from the model, so we don't ever need to apply an inferred mapping on them.