Node-fs-extra: [feature] How about tell user whether the file is created when use the ensureFile method?

Created on 31 Jul 2017 · 3Comments · Source: jprichardson/node-fs-extra

The use case is I use the ensureFile to create json file if it not created before, but I need to inject the {} into it first time because the jsonfile readFile method will throw the Unexpected end of JSON input error when the json file is empty.

I think it would be nice if support that, such as, I can do it by the code below

function renderBundleJSON(file, map) {
  return fse.ensureFile(file).then(isExist => {
    if (!isExist) {
      fse.writeJSONSync(file, {});
    }
    return fse.readJson(file).then(json => {
      return fse.outputJson(file, Object.assign(json, map), {
        spaces: 2
      });
    });
  });
}

question

Source

monkindey

All 3 comments

But I workaround it by

function renderBundleJSON(file, map) {
  return fse.ensureFile(file).then(() => {
    return fse
      .readJson(file)
      .then(json => {
        return fse.outputJson(file, Object.assign(json, map), {
          spaces: 2
        });
      })
      .catch(err => {
       // here
        return fse.writeJson(file, {}).then(() => renderBundleJSON(file, map));
      });
  });
}

monkindey on 31 Jul 2017

@monkindey Using ensureFile here is an anti-pattern, because it means an extra filesystem operation if the file doesn't exist.

Here's a better way to do it; assuming that file will never be a directory or a file that isn't valid JSON:

function renderBundleJSON(file, map) {
  return fse.pathExists(file)
    .then(isExist => isExist ? fse.readJson(file) : Promise.resolve({}))
    .then(json => {
      return fse.outputJson(file, Object.assign(json, map), {
        spaces: 2
      });
    });
}