Allow SQL Server JSON mapping to non-max nvarchar

src/EFCore.SqlServer/Storage/Internal/SqlServerTypeMappingSource.cs

@@ -237,10 +237,12 @@ static SqlServerTypeMappingSource()
         if (clrType == typeof(JsonTypePlaceholder))
         {
             // We get here when a structural type (complex type or owned entity) is mapped to JSON.
-            return storeTypeName switch
+            return mappingInfo.StoreTypeNameBase switch
             {
                 "json" => SqlServerStructuralJsonTypeMapping.JsonTypeDefault,
-                "nvarchar(max)" => SqlServerStructuralJsonTypeMapping.NvarcharMaxDefault,
+
+                // Note that if the store type is non-max (e.g. nvarchar(2000)), it gets cloned outside for the right size.
+                "nvarchar" => SqlServerStructuralJsonTypeMapping.NvarcharMaxDefault,
 
                 null when _isJsonTypeSupported => SqlServerStructuralJsonTypeMapping.JsonTypeDefault,
                 null => SqlServerStructuralJsonTypeMapping.NvarcharMaxDefault,

test/EFCore.SqlServer.Tests/Storage/SqlServerTypeMappingSourceTest.cs

@@ -1602,6 +1602,20 @@ public void Json_is_mapped_to_nvarchar_with_compatibility_level_170_when_explici
         Assert.Equal("nvarchar(max)", typeMappingSource.FindMapping(typeof(int[]), "nvarchar(max)").StoreType);
     }
 
+    [ConditionalFact]
+    public void Json_can_be_mapped_to_nvarchar_non_max()
+    {
+        var typeMappingSource = CreateTypeMappingSource(o => o.UseSqlServer());
+
+        Assert.Equal(
+            "nvarchar(2000)",
+            typeMappingSource.FindMapping(typeof(JsonTypePlaceholder), storeTypeName: "nvarchar(2000)").StoreType);
+
+        Assert.Equal(
+            "nvarchar(2000)",
+            typeMappingSource.FindMapping(typeof(int[]), storeTypeName: "nvarchar(2000)").StoreType);
+    }
+
     private SqlServerTypeMappingSource CreateTypeMappingSource(Action<DbContextOptionsBuilder> optionsAction = null)
     {
         var optionsBuilder = new DbContextOptionsBuilder();