feature: add option to convert property name to snake_case or camelCase

[arcovoltaico]

My json contains some snake_case atributes, but my class is camelCase.
In order to avoid expose naming the class, I'd like something like this:

let users = plainToClass(User, userJson, {snakeToCamel: true});

Thanks!

[maroon1]

@arcovoltaico you may need change-object-case

[kevinrambaud]

Using the Expose decorator and specifying the name property as an option should do what you want as described at https://github.com/typestack/class-transformer#exposing-properties-with-different-names

It should work for both cases where you plainToClass and classToPlain.

[quanganhtran]

I'm also interested in this feature. Having something on top of Expose.name would be great.

I think both change-object-case and a configuration on plainToClass or classToPlain would be too aggressive.

I'd propose a syntactic sugar for Expose (e.g. name accepting a function to compute exposed name based on class name, so user doesn't have to manually specify each of them, or simply a flag that configures this). Or a decorator on the whole class that shallowly applies a naming scheme to all its fields. This can be useful to have when building class-oriented DTO structures, to be used on the API layer

On why messing with cases, our code style recommends camelCase in the code while our API guideline recommends snake_case for REST payloads.

(Inspiration: scala circe where snake case <> camel case is configured per class)

[incompletude]

For me a global option to choose the proper casing would be great.

[chriswhite199]

For the time being using these two libraries:

• https://github.com/bendrucker/snakecase-keys
• https://github.com/sindresorhus/camelcase-keys

can be used to wrap the output of classToPlain and pre-input to plainToClass:

plainToClass(camelcaseKeys(plain), ClassName)
snakeCaseKeys(classToPlain(obj))

[NoNameProvided]

As mentioned in this thread, there are external tools, which do this and it's 2 lines to wrap class-transformer in a custom function that calls these functions when needed. As a result of this, I am marking this as a low priority. Eventually, it may get landed but not soon. In the meantime, please vote on the initial comment if you want to show your support and don't add extra +1 comments. If you have some comments about the design of the feature feel free to add your two cents.

[talski]

For the time being using these two libraries:

• https://github.com/bendrucker/snakecase-keys
• https://github.com/sindresorhus/camelcase-keys

can be used to wrap the output of classToPlain and pre-input to plainToClass:

plainToClass(camelcaseKeys(plain), ClassName)
snakeCaseKeys(classToPlain(obj))

Any thoughts on remove a prefix before convert case? I need it to workaround a TypeORM issue

[chriswhite199]

You'll either need to find a library to do the prefix stripping, or just use map-obj like the above two libraries are using to preprocessor the object before passing to either

https://www.github.com/bendrucker/snakecase-keys/tree/master/index.js

[udleinati]

@chriswhite199 adding extra value to this issue, we were using snakecase-keys and camelcase-keys to convert requests/responses, and everything was working as expected until we had a heavy load to deal with. We end up changing those packages by fast-case, it's much more CPU efficient. CPU went down from 80% to 35% or so.