ServiceStack - how to add custom typescript decorators?

Question

I'm generating typescript dtos via C# models under ServiceStack.

I'm hoping to use typestack/class-validator which operates by evaluating several decorators that it provides.

Is there a way in ServiceStack's typescript generation for including arbitrary decorators beyond the usual DataAnnotations attributes on the C# side or must I create new C# attributes to mirror what I want to show up on the typescript side?

Answer 1

Edit:

As your solution is more UX-friendly I've also decided to implement this feature where you can instead use [Emit{Language}] attributes to generate code before each type or property, e.g:

[EmitTypeScript("@Validate()")]
public class User
{
    [EmitTypeScript("@IsNotEmpty()", "@IsEmail()")]
    public string Email { get; set; }
}

You can also use [EmitCode] to emit code for multiple languages, e.g. this adds annotations to both Dart & TypeScript.

[EmitCode(Lang.Dart | Lang.TypeScript, "@Validate()")]
public class User
{
    [EmitCode(Lang.Dart | Lang.TypeScript, new[]{ "@IsNotEmpty()", "@IsEmail()" })]
    public string Email { get; set; }
}

---

In addition you can use the PreTypeFilter, InnerTypeFilter & PostTypeFilter to generate source code before and after a Type definition, e.g. this will append the @validate() annotation on non enum types:

TypeScriptGenerator.PreTypeFilter = (sb, type) => {
    if (!type.IsEnum.GetValueOrDefault())
    {
        sb.AppendLine("@Validate()");
    }
};

The InnerTypeFilter gets invoked just after the Type Definition which can be used to generate common members for all Types and interfaces, e.g:

TypeScriptGenerator.InnerTypeFilter = (sb, type) => {
    sb.AppendLine("id:string = `${Math.random()}`.substring(2);");
};

They previously didn't exist but I've also just added PrePropertyFilter & PostPropertyFilter for generating source before and after properties, e.g:

TypeScriptGenerator.PrePropertyFilter = (sb , prop, type) => {
    if (prop.Name == "Id")
    {
        sb.AppendLine("@IsInt()");
    }
};

Pre/Post PropertyFilter's are available from v5.9.3+ that's now available on MyGet.