merge getCustomTransformers instead of replacing it

[colorcube]

AFAIK the problem with overriding Nx's own ts-loader transformer is that it'll then no longer support Nx's build cache

Here are some examples how to merge getCustomTransformers:

• Issue with adding fastify in Nest plugin nrwl/nx#6915
• Any idea on how to use nestjs cli plugin with nx? nrwl/nx#4135
• support for nestjs compiler plugins (e.g. for swagger) nrwl/nx#2147

[colorcube]

build cache works with following webpack config
if deepkit transformer works too has to be tested

webpack-deepkit.config.js:

const typeCompiler = require('@deepkit/type-compiler');

module.exports = (config, _context) => {
    config.module.rules
        .filter((rule) => rule.loader?.includes('ts-loader'))
        .forEach((tsRule) => {
            tsRule.options.getCustomTransformers = addDeepkitTransformer(tsRule.options.getCustomTransformers)
        });


    return config
};

// this enables @deepkit/type's type compiler
function addDeepkitTransformer(prevGetCustomTransformers) {
    return (program) => {
        const customTransformers = { ...(prevGetCustomTransformers ? prevGetCustomTransformers(program) : undefined) };
        customTransformers.before = [
            typeCompiler.transformer,
            ...(customTransformers.before || [])
        ];
        customTransformers.afterDeclarations = [
            typeCompiler.declarationTransformer,
            ...(customTransformers.afterDeclarations || [])
        ];
        // console.log(customTransformers);
        return customTransformers
    }
}

[colorcube]

I think I managed to add the Deepkit transformer to getCustomTransformers and preserve the Nx transformer.
Nx build cache works again.