react-native-fs: How to read json file content?

Question

Below is my code to read a JSON file which is already downloaded and stored in "TemporaryDirectoryPath".

var fileName = getFileNameFromUrl(url); RNFS.downloadFile({ fromUrl: url, toFile: `${RNFS.TemporaryDirectoryPath}/`+fileName }).promise.then(r => { var content = RNFS.readFile(`${RNFS.TemporaryDirectoryPath}/`+fileName, 'utf8'); console.log(content); });

I am getting an object of type "Promise" as below

Promise {_40: 0, _65: 0, _55: null, _72: null} _40: 0 _55: "{"show_explanation":1,"answer_result":2, //More json content will be here}" _65: 1 _72: null

How to read content from that Promise object?

this question is probably a duplicate of: stackoverflow.com/questions/49770756/… — Macilias
– Macilias, Commented Nov 22, 2019 at 14:49
and since both of them has not been properly answered until yet, I failed a more specific one, with multiple approaches showcasing the state of react-native-fs: stackoverflow.com/questions/59028704/… — Macilias
– Macilias, Commented Nov 25, 2019 at 9:59

Mario Rozic · Accepted Answer · 2017-12-15 10:07:14Z

2

Why dont you just import it with "import"

import AnyName from './pathToYourJSONfile';

I have to write here, low rep for adding comments! :/

answered Dec 15, 2017 at 10:07

Mario Rozic

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10 Comments

Sagar Over a year ago

The file is getting downloaded and storing the file name in the local DB, and later I have to read the file content and display. So I don't know what is the filename to import, and there can be multiple files which I may need to download.

Mario Rozic Over a year ago

wait ...1st you download this json file from some server and save its name to db ? ...and than you need to import it to your app ?

Sagar Over a year ago

I am not importing. I have to read the content of the file which I am downloading from an URL. I updated the code, please refer.

Mario Rozic Over a year ago

Do you know whats in that file ? and will it always be the same content?

Sagar Over a year ago

No, content will be different. But the content structure will be same. And it's not about a single file, I need to download multiple files. and the number of files to download also not a constant.

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Rick Liao · Accepted Answer · 2018-12-25 10:15:50Z

You already know RNFS.readFile() return Promise.

So you just need to learn how to use Promise.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/then

var fileName = getFileNameFromUrl(url); RNFS.downloadFile({ fromUrl: url, toFile: `${RNFS.TemporaryDirectoryPath}/` + fileName }) .then(r => { RNFS.readFile(`${RNFS.TemporaryDirectoryPath}/` + fileName, 'utf8') .then(content => { console.log(content); }) });

I tried your suggestion, but still the output is: ` { _40: 0, _65: 0, _55: null, _72: null }`

Macilias · Accepted Answer · 2019-11-27 10:36:20Z

I had the same problem and managed to finally get the content with following snipped:

let asset_content = null; try { await RNFetchBlob.fs.readFile(assetFile_path, 'utf8') .then((data) => { asset_content = data; console.log("got data: ", data); }) .catch((e) => { console.error("got error: ", e); }) } catch (err) { console.log('ERROR:', err); } const assets = JSON.parse(asset_content);

You might also have to ensure that the content has been saved as 'utf8'

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