JsonHookup

For when you wish System.Text.Json would honor DataContract and DataMember attributes

Overview

JsonHookup provides a "modifier" to System.Text.Json, so that its JsonSerializer can (largely) honor [DataContract] / [DataMember] attributes on classes being serialized and deserialized.

This is especially useful when a library abstracts their ISerializer, but the DTO classes are all decorated using [DataMember] attributes.

Background

System.Text.Json infamously refuses to honor System.Runtime.Serialization constructs such as [DataContract], [DataMember], and [IgnoreDataMember]. And historically before .NET 6/7, that was more defensible: System.Text.Json couldn't do much more than honor custom property names without involving cumbersome extensibility.

But as of .NET7, a foothold has appeared: Modifiers for the Type Info Resolver

Usage

// Apply JsonHookup to an instance of JsonSerializerOptions cloned from the static Default
JsonSerializerOptions jsonOptionsFromDefault = JsonHookup.AddHookupToDefault(HookupOptions.DefaultExplicit);

JsonSerializer.Serialize(myObject, jsonOptionsFromDefault);

// or

// Apply JsonHookup to some existing JsonSerializerOptions
JsonSerializerOptions existingJsonOptions;
someExistingOptions.AddHookup(HookupOptions.DefaultExplicit);

JsonSerializer.Serialize(myObject, existingJsonOptions);

// or

JsonSerializerOptions existingJsonOptions;
HookupOptions hookupOptions = new() // For example...
{ 
  Ignore = HookupParts.DataMemberOrder, // ignore data member order
  DataContractMode = HookupMode.Explicit, // use the hookup only on classes decorated with [DataContract] or [UseDataContract]
  DataMemberMode = HookupMode.Explicit, // only include properties decorated with [DataMember]
}
existingJsonOptions.AddHookup(hookupOptions);

JsonSerializer.Serialize(myObject, existingJsonOptions);

Serializer options lifetime

Note: general guidance in System.Text.Json is to re-use an instance of JsonSerializerOptions as widely as possible. This guidance still applies with JsonHookup.

Target Framework

JsonHookup depends on functionality added in .NET 7.

Status

This project is completely experimental.

Known Issues as of v0.1.2

• Interface types are not supported. Only concrete class or struct types are supported.
• Member ordering semantics are rudimentary. Data Contract calls for some additional behavior.
• Emit Default Value is ignored
• Testing is skeletal at best
• The only supported TypeInfoResolver is DefaultJsonTypeInfoResolver