[BUG]: Deserialize returning empty object in string property

[m4kz]

Version

5.1.0

Description

When I deserialize the class below from {"some": "something"}, i get a weird result

uid becomes an empty object, while name is undefined,.

Shouldn't uid also be undefined?

This is the resukt i get:

name: undefined
some: 'something'
uid: {}

Error

No response

Reproduction

class:

@JsonObject()
export class BaseModel {
    @JsonProperty()
    uid?: string;      
    @JsonProperty()
    some?: string|null;
    @JsonProperty() 
    name?: string | null; 
    constructor(uid?: string, some?: string | null, name?: string | null ) {
        this.uid = uid;
        this.some = some;
        this.name = name;
     }
}

Deserialize:
const deserializedbm : BaseModel= <BaseModel2>defaultSerializer.deserialize<BaseModel>({"some": "something"}, BaseModel2);

On which OS the bug appears?

Ubuntu

What is your project type?

NodeJs

On which build mode the bug appears?

No response

Anything else?

No response

[GillianPerard]

Hi, thanks for using my lib.

You're right, there is weird behavior there.

Until I fix, you could declare your class as:

@JsonObject()
export class BaseModel {
    @JsonProperty()
    public uid?: string;

    @JsonProperty()
    public some?: string | null;

    @JsonProperty() 
    public name?: string | null;
}

[m4kz]

Thank you.
It works, but then i cannot have a constructor.

[GillianPerard]

Yes indeed, let me fix asap.

[GillianPerard]

I checked deeper and there is a problem with Typescript.

You can define a property with multiple possible types, for example: uid: string | undefined but as typescript is not actually a typed language, the type becomes Object in reality.

For a previous PR, I affected a default value equal to {} when I build an instance of the object to deserialize because of people who want to pass an object as constructor params (see: #161).

I imagine 3 solutions:

• I keep my code unchanged and instead of having a constructor, you use the method I sent you in a comment above (because the JsonObject classes should only be used for DTO not for some logic)
• I remove the default params from my code so your code will work but the current users that use object param will have to change their code to set a default value or use ? syntax to avoid errors
• Change my code; instead of generating empty instances and then applying data that users pass to the deserialize function to the instance, I could try to pass the properties from data that match the constructor params and the assignment but this solution is way more tricky because I should parse the constructor as string to guess what the user had in mind

[m4kz]

Could be possible to have default configurable? either in JsonProperty? or in JsonSerializer?

const customSerializer = new JsonSerializer({
//Default type
defaultType:  ''
})

[GillianPerard]

Perhaps in the JsonObject, I could create a param to provide default params for the constructor and if no one is set then i provide undefined.

[GillianPerard]

The new version 6.0.0 is here.

You have nothing to do, your could should work now.
But I fou want you can specify the default values for the params of your constructor directly inside the JsonObject:

@JsonObject({ constructorParams: [undefined, null, null] })
export class BaseModel {
    @JsonProperty()
    uid?: string;      
    @JsonProperty()
    some?: string|null;
    @JsonProperty() 
    name?: string | null; 

    constructor(uid?: string, some?: string | null, name?: string | null ) {
        this.uid = uid;
        this.some = some;
        this.name = name;
     }
}