Flatten Strapi 4's response JSON

README.md

Update 29/11/2022

There is a plugin on Strapi Marketplace that do this response transforming stuffs in a more configurable way. Checkout this if you are interested.

flatten-response.js

// src/middlewares/flatten-response.js
function flattenArray(obj) {
  return obj.map(e => flatten(e));
}

function flattenData(obj) {
  return flatten(obj.data);
}

function flattenAttrs(obj) {
  let attrs = {};
  for (var key in obj.attributes) {
    attrs[key] = flatten(obj.attributes[key]);
  }
  return {
    id: obj.id, 
    ...attrs
  };
}

function flatten(obj) {
  if(Array.isArray(obj)) {
    return flattenArray(obj);
  }
  if(obj && obj.data) {
    return flattenData(obj);
  }
  if(obj && obj.attributes) {
    return flattenAttrs(obj);
  }
  return obj;
}

async function respond(ctx, next) {
  await next();
  if (!ctx.url.startsWith('/api')) {
    return;
  }
  console.log(`API request (${ctx.url}) detected, transforming response json...`);
  ctx.response.body = {
    data: flatten(ctx.response.body.data),
    meta: ctx.response.body.meta
  };
}

module.exports = () => respond;

middlewares.js

// config/middlewares.js
module.exports = [
  'strapi::errors',
  'strapi::security',
  'strapi::cors',
  'strapi::poweredBy',
  'strapi::logger',
  'strapi::query',
  'strapi::body',
  'global::flatten-response',
  'strapi::favicon',
  'strapi::public',
];

@jonasmarco It works, check that the code was copied well and also your project's tsconfig.json.

Code working in the TS playground.