README.md

XO.EntityFrameworkCore.NpgsqlJsonSerializerOptions

An Entity Framework Core plugin that adds support for JsonSerializerOptions to the Npgsql provider's built-in JSON POCO mapping. You could use it to influence the property naming policy, or to use JSON source generation.

NOTE: Version 8.0 of the Npgsql EF provider introduced full support for Entity Framework Core's JSON columns feature. This plugin is for Npgsql's native POCO mapping, not the EF Core feature. You probably want to use JSON columns in new projects!

• https://learn.microsoft.com/en-us/ef/core/what-is-new/ef-core-7.0/whatsnew#json-columns
• https://www.npgsql.org/efcore/mapping/json.html?tabs=data-annotations%2Cpoco

Usage

1. Opt in to Npgsql's dynamic JSON POCO mapping, which is disabled by default in Npgsql 8.0. An example from this project's tests:

   private static readonly DbDataSource _dataSource = new NpgsqlDataSourceBuilder(
       "Host=localhost;Username=postgres;Password=password;Database=XO.EntityFrameworkCore.Tests")
       .EnableDynamicJson()
       .Build();

2. Call the extension method to add the plugin to your DbContext.

   protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
   {
       optionsBuilder
           .UseNpgsql(_dataSource)
           .UseNpgsqlJsonSerializerOptions();
   }

3. Call UseJsonSerializerOptions to configure JsonSerializerOptions for a specific property.

   protected override void OnModelCreating(ModelBuilder modelBuilder)
   {
       modelBuilder.Entity<MyEntity>(entity =>
       {
           entity.Property(x => x.MyJsonProperty)
               .HasColumnType("jsonb")
               .UseJsonSerializerOptions(new JsonSerializerOptions
               {
                   DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
                   PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
               });
       });
   }

Options

Default Serializer Options

To apply default JsonSerializerOptions to all json and jsonb columns, pass the default instance to the options builder:

Note: When configuring the default serializer options, pass the same instance every time your configuration callback is invoked. Otherwise, Entity Framework will detect the options have changed and construct a new IServiceProvider for every DbContext!

private static readonly JsonSerializerOptions defaultOptions
    = new JsonSerializerOptions
    {
        DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
        PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
    };

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
    optionsBuilder
        .UseNpgsql("Host=localhost")
        .UseNpgsqlJsonSerializerOptions(defaultOptions);
}

JsonSerializerValueComparer<T>

By default, the plugin configures affected entity properties to use JsonSerializerValueComparer<T> for value equality comparison, which serializes each value to JSON and compares the resulting strings. If you prefer the default value comparer's semantics for your value type(s), or if you just don't want the additional serialization overhead, you can disable it:

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
    optionsBuilder
        .UseNpgsql("Host=localhost")
        .UseNpgsqlJsonSerializerOptions(useJsonSerializerValueComparer: false);
}