Fix arrays over JsonDocument/JsonElement (#3747)

Fixes #3677

(cherry picked from commit e9528b4)

Author: roji

src/EFCore.PG/Storage/Internal/Mapping/NpgsqlArrayTypeMapping.cs

@@ -145,7 +145,7 @@ private static RelationalTypeMappingParameters CreateParameters(string storeType
         if (elementJsonReaderWriter is not null && !typeof(TElement).UnwrapNullableType().IsAssignableTo(elementJsonReaderWriter.ValueType))
         {
             throw new InvalidOperationException(
-                $"When building an array mapping over '{typeof(TElement).Name}', the JsonValueReaderWriter for element mapping '{elementMapping.GetType().Name}' is incorrect ('{elementJsonReaderWriter.ValueType.GetType().Name}' instead of '{typeof(TElement).UnwrapNullableType()}', the JsonValueReaderWriter is '{elementJsonReaderWriter.GetType().Name}').");
+                $"When building an array mapping over '{typeof(TElement).Name}', the JsonValueReaderWriter for element mapping '{elementMapping.GetType().Name}' is incorrect ('{elementJsonReaderWriter.ValueType.Name}' instead of '{typeof(TElement).UnwrapNullableType()}', the JsonValueReaderWriter is '{elementJsonReaderWriter.GetType().Name}').");
         }
 
         // If there's no JsonValueReaderWriter on the element, we also don't set one on its array (this is for rare edge cases such as

src/EFCore.PG/Storage/Internal/Mapping/NpgsqlJsonTypeMapping.cs

@@ -32,7 +32,7 @@ public NpgsqlJsonTypeMapping(string storeType, Type clrType, CoreTypeMapping? el
             storeType,
             clrType,
             storeType == "jsonb" ? NpgsqlDbType.Jsonb : NpgsqlDbType.Json,
-            jsonValueReaderWriter: JsonStringReaderWriter.Instance,
+            jsonValueReaderWriter: clrType == typeof(string) ? JsonStringReaderWriter.Instance : null,
             elementTypeMapping: elementTypeMapping)
     {
         if (storeType != "json" && storeType != "jsonb")

test/EFCore.PG.Tests/Storage/NpgsqlTypeMappingSourceTest.cs

@@ -1,12 +1,12 @@
 using System.Net;
 using System.Net.NetworkInformation;
+using System.Text.Json;
 using Microsoft.EntityFrameworkCore.Storage.Json;
 using NetTopologySuite.Geometries;
 using Npgsql.EntityFrameworkCore.PostgreSQL.Infrastructure;
 using Npgsql.EntityFrameworkCore.PostgreSQL.Internal;
 using Npgsql.EntityFrameworkCore.PostgreSQL.Storage.Internal;
 using Npgsql.EntityFrameworkCore.PostgreSQL.Storage.Internal.Mapping;
-using Npgsql.EntityFrameworkCore.PostgreSQL.TestUtilities;
 
 namespace Npgsql.EntityFrameworkCore.PostgreSQL.Storage;
 
@@ -313,6 +313,20 @@ public void Json_primitive_collection()
         Assert.Same(typeof(int), elementMapping.ClrType);
     }
 
+    [Theory]
+    [InlineData(typeof(JsonDocument[]))]
+    [InlineData(typeof(List<JsonDocument>))]
+    [InlineData(typeof(JsonElement[]))]
+    [InlineData(typeof(List<JsonElement>))]
+    public void Array_of_json_type(Type clrType)
+    {
+        var mapping = CreateTypeMappingSource().FindMapping(clrType);
+        Assert.NotNull(mapping);
+        var arrayMapping = Assert.IsType<NpgsqlArrayTypeMapping>(mapping, exactMatch: false);
+        Assert.Equal("jsonb[]", arrayMapping.StoreType);
+        Assert.Same(clrType, arrayMapping.ClrType);
+    }
+
     #endregion JSON
 
     #region Multirange