Optional properties are ignored

[parloti]

The following code in C # ...

public int? ParentId { get; set; }

... results in the following in Typescript ...

parentId: number;

... while the correct one should be:

parentId?: number;

[jburzynski]

Could you paste the definition of the C# type, the content of the generated TS file, the configuration (tgconfig.json) and the generation spec (if used)?

I'm not sure right now if this is a problem with the tool or the configuration, additional information would help determine the problem.

Thanks

[parloti]

I am only using the attribute in classes in C#, I have not used any additional configuration.

C#

using System.Collections.Generic;
using TypeGen.Core.TypeAnnotations;

namespace Business
{
    [ExportTsClass(OutputDir = @"../Presentation/ClientApp/src/app/models")]
    public class CommentDTO
    {
        public int Id { get; set; }
        public string Message { get; set; }
        public ICollection<int> AnswerIds { get; set; }
        public int? ParentId { get; set; }
        public int ActivityId { get; set; }
    }
}

Typescript (after TypeGen -p "Business" generate)

export class CommentDTO {
    id: number;
    message: string;
    answerIds: number[];
    parentId: number;
    activityId: number;
}

[Allov]

While parentId?: number will render the property optional, it's not nullable (like in C#). Should you not be defining it as such: parentId?: number | null ?

Exemple:

Maybe it's a tsc configuration though...

[Allov]

I think the setting you're looking for is csNullableTranslation. Put that in your tsconfig.json

"csNullableTranslation": "null"

[jburzynski]

I am only using the attribute in classes in C#, I have not used any additional configuration.

C#

using System.Collections.Generic;
using TypeGen.Core.TypeAnnotations;

namespace Business
{
    [ExportTsClass(OutputDir = @"../Presentation/ClientApp/src/app/models")]
    public class CommentDTO
    {
        public int Id { get; set; }
        public string Message { get; set; }
        public ICollection<int> AnswerIds { get; set; }
        public int? ParentId { get; set; }
        public int ActivityId { get; set; }
    }
}

Typescript (after TypeGen -p "Business" generate)

export class CommentDTO {
    id: number;
    message: string;
    answerIds: number[];
    parentId: number;
    activityId: number;
}

I think optional properties are only allowed in TypeScript interfaces (not TypeScript classes). I've just double-checked this and I couldn't find information about optional properties for TypeScript classes in TypeScript documentation.

But maybe this is allowed, but I just haven't found the information - can you please check if it compiles if you put an optional property in a TypeScript class (or have you found maybe some information in the docs that this is possible)?

If you'd like to generate an optional property in a TypeScript interface, you'd need to use TsOptionalAttribute (or the .Optional() method in the generation spec) for the member.

Since the ? type suffix in C# means the type is nullable, I thought it would be a good idea to translate it to a type union with null or undefined in TypeScript. As @Allov mentioned, you can choose which TS type union (null, undefined, both or none) to use for nullable C# types using the "csNullableTranslation" config parameter.

An example of csNullableTranslation:

• if you put "csNullableTranslation": "null" in the config, this will translate MyValueType? (the member type) in C# to MyValueType | null in TS
• if you put "csNullableTranslation": "null|undefined" in the config, this will translate MyValueType? (the member type) in C# to MyValueType | null | undefined in TS
• if you don't specify csNullableTranslation in the config, it will use the default value "" (which means no type unions are used) and MyValueType? (the member type) in C# will translate to MyValueType in TS

So C# nullable types are translated to type unions (with null, undefined, neither or both) in TS;
and to specify an optional property for TS interface, you can use TsOptionalAttribute.

[parloti]

Thank you guys,

The solution was to use:

{
   ...
    parentId: null;
  ...
} as CommentDTO 

[johnknoop]

Sorry for hijacking the thread, but I'm looking to replace TypeWriter because it doesn't handle nullable reference types in C#. Judging by this thread, TypeGen doesn't automatically translate C# nullables into TS optionals. Is it a simple thing to configure it to do that?

[elwynelwyn]

Also bumping old thread sorry^^

Would love a way to make C# nullable types optional TS properties.
I've set up csNullableTranslation to undefined which is correctly generating the union type T | undefined, however this means you still have to manually specify these properties as undefined when creating these objects.

class Car {
    string Model { get; set; }
    Sunroof?: Sunroof { get; set; }
}

becomes

interface Car {
    model: string;
    sunroof: Sunroof | undefined;
}

and now for ever car I define, I must do

const car: Car = {
    model: 'some cool car',
    sunroof: undefined
};

whereas I would prefer to define all cars without sunroofs like:

const car: Car = {
    model: 'some cool car'
};

(imagine there are many of these properties which can optionally be used in different situations, and currently I have to set every one of them as undefined).

I'd prefer not to instrument many many C# classes / properties with TypeGen attributes, and instead base it from our existing nullable properties.
(I did try the attribute but it didn't seem to actually work - perhaps because I am using a GenerationSpec? I'm also unable/unwilling to manually set properties as optional in the spec due to there being way too many / not wanting a giant blog of config)

Any other workarounds to suggest?
EDIT: and if this isn't possible, is this something you would be open to supporting if I put together a PR? (either as a new config option, or a new value for csNullableTranslation)