如何使用 React-Native-fs 读取 JSON 文件

Question

我有一个包含内容的 asset.json 文件，需要在 react-native 应用程序中读取它。我已经认为必须手动将它复制到本机实现，并且我可以验证该文件是否存在（并且可读：-rw-r--r--）。因为它在那里并且我正在使用承诺来获得它，请告诉我输出是否仍然是：

{"_40":0,"_65":0,"_55":null,"_72":null}

而不是文件的内容。

const path = RNFetchBlob.fs.dirs.DocumentDir + '/' + ASSET_FILENAME;
  if (await RNFS.exists(path)){
    console.log("BLAH EXISTS");
  } else {
    console.log("BLAH DOES NOT EXIST");
  }
  const asset_content = await RNFS.readFile(path);
  console.log("local asset_content:", asset_content);
  const assets = JSON.parse(asset_content);
  console.log("local assets:", assets);

输出为：

[10:03:55] I | ReactNativeJS ▶︎ BLAH EXISTS

[10:03:55] I | ReactNativeJS ▶︎ 'local asset_content:', '{"_40":0,"_65":0,"_55":null,"_72":null}'

[10:03:55] I | ReactNativeJS ▶︎ 'local assets:', { _40: 0, _65: 0, _55: null, _72: null }

另一方面，如果我出于某种原因使用 promisify，如某些帖子中所建议的那样，应用程序会在调用已读取的承诺文件时冻结。这里的代码应用了更改：

 const path = RNFetchBlob.fs.dirs.DocumentDir + '/' + ASSET_FILENAME;
  if (await RNFS.exists(path)){
    console.log("BLAH EXISTS");
  } else {
    console.log("BLAH DOES NOT EXIST");
  }
  const readFileAsync = promisify(RNFS.readFile);
  const asset_content = await readFileAsync(path);
  console.log("local asset_content:", asset_content);
  const assets = JSON.parse(asset_content);
  console.log("local assets:", assets);

及其输出：

[10:24:16] I | ReactNativeJS ▶︎ BLAH EXISTS

文件不大，只有81行有效JSON。现在，如果我使用 promise 来检查是否有这样的异常：

  const path = RNFetchBlob.fs.dirs.DocumentDir + '/' + ASSET_FILENAME;
  if (await RNFS.exists(path)){
    console.log("BLAH EXISTS");
  } else {
    console.log("BLAH DOES NOT EXIST");
  }
  const readFileAsync = promisify(RNFS.readFile);
  let asset_content = null;
  readFileAsync(path, 'utf8')
    .then((str) => {
      console.log("got result: ", str);
      asset_content = str;
    })
    .catch((e) => {
      console.log("got error:", e);
    });
  console.log("local asset_content:", asset_content);
  const assets = JSON.parse(asset_content);
  console.log("local assets:", assets);

我仍然没有异常，结果为空：

[10:45:00] I | ReactNativeJS ▶︎ BLAH EXISTS

[10:45:00] I | ReactNativeJS ▶︎ 'local asset_content:', null

[10:45:00] I | ReactNativeJS ▶︎ 'local assets:', null

当我摆脱 promisify 并离开 promise 处理时，我回到了我开始的地方：

  const path = RNFetchBlob.fs.dirs.DocumentDir + '/' + ASSET_FILENAME;
  if (await RNFS.exists(path)){
    console.log("BLAH EXISTS");
  } else {
    console.log("BLAH DOES NOT EXIST");
  }
  let asset_content = null;
  RNFS.readFile(path, 'utf8')
    .then((str) => {
      console.log("got result: ", str);
      asset_content = str;
    })
    .catch((e) => {
      console.log("got error:", e);
    });
  console.log("local asset_content:", asset_content);
  const assets = JSON.parse(asset_content);
  console.log("local assets:", assets);

输出：

[10:49:45] I | ReactNativeJS ▶︎ BLAH EXISTS

[10:49:45] I | ReactNativeJS ▶︎ 'local asset_content:', null

[10:49:45] I | ReactNativeJS ▶︎ 'local assets:', null

[10:49:45] I | ReactNativeJS ▶︎ 'got result: ', '{"_40":0,"_65":0,"_55":null,"_72":null}'

请帮忙。文件处理对我们的应用程序至关重要。

更新：这是文件 asset.json 的内容，它被 ASSET_FILE:

引用

{
  "protobuf": [
    {
      "name": "tiny-fovapp-4c",
      "lite": false,
      "compressed": false,
      "selected": false
    },
    {
      "name": "tiny-yolo-4c-quantized",
      "lite": true,
      "compressed": true,
      "selected": false
    },
    {
      "name": "tiny-yolo-4c",
      "parentFolder": "/data/user/0/com.foviar/files/",
      "modelFilePath": "ai/protobuf/tiny-yolo-4c.pb",
      "labelsFilePath": "ai/protobuf/tiny-yolo-4c-labels.txt",
      "lite": false,
      "compressed": false,
      "selected": true
    },
    {
      "name": "tiny-yolo-4c",
      "lite": true,
      "compressed": false,
      "selected": false
    }
  ],
  "testImages": [
    {
      "name": "IMG_6924.jpg",
      "parentFolder": "/data/user/0/com.foviar/files/",
      "filePath": "ai/testimgs/IMG_6924.jpg"
    },
    {
      "name": "IMG_6924.png",
      "parentFolder": "/data/user/0/com.foviar/files/",
      "filePath": "ai/testimgs/IMG_6924.png"
    },
    {
      "name": "IMG_6929.jpg",
      "parentFolder": "/data/user/0/com.foviar/files/",
      "filePath": "ai/testimgs/IMG_6929.jpg"
    },
    {
      "name": "Part1.png",
      "parentFolder": "/data/user/0/com.foviar/files/",
      "filePath": "ai/testimgs/Part1.png"
    },
    {
      "name": "Part1_10.png",
      "parentFolder": "/data/user/0/com.foviar/files/",
      "filePath": "ai/testimgs/Part1_10.png"
    }
  ],
  "parts": [
    {
      "name": "Part1",
      "parentFolder": "/data/user/0/com.foviar/files/",
      "modelFilename": "ai/models/Part1.png",
      "drawingFilename": "ai/drawings/Part1.png",
      "annotationFilename": "ai/annotations/Part1.xml"
    },
    {
      "name": "Part2",
      "parentFolder": "/data/user/0/com.foviar/files/",
      "modelFilename": "ai/models/Part2.png",
      "drawingFilename": "ai/drawings/Part2.png",
      "annotationFilename": "ai/annotations/Part2.xml"
    },
    {
      "name": "Part3",
      "parentFolder": "/data/user/0/com.foviar/files/",
      "modelFilename": "ai/models/Part3.png",
      "drawingFilename": "ai/drawings/Part3.png",
      "annotationFilename": "ai/annotations/Part3.xml"
    }
  ]
}

Answer 1

Steps to read json file in react-native applications :-

1.将其导入您的组件

import ASSET_FILE from '../assets/files/asset.json';

// import filename from 'path to your asset file';

2。现在在函数中

jsonParser(){
    var data = JSON.parse(JSON.stringify(ASSET_FILE));
    var tempProtobuf = []
    var temptestImages= []
    var tempparts= []
    tempProtobuf = data.Protobuf
    temptestImages = data.testImages
    tempparts = data.parts
}

// Now three of your objects are there in tempProtobuf, temptestImages, tempparts array respectively.

Iterate if or save in state if you want to show in your application..

希望这对您有所帮助...谢谢 :)

Answer 2

我终于设法将静态文件的内容复制到应用程序文档目录中，并通过使用 NRFechtBlob.fs 实现和提供的编码参数来读取和维护它，如下所示：

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);

呸。没想到2019年文件处理会这么痛苦

如何使用 React-Native-fs 读取 JSON 文件

How to read JSON file with React-Native-fs

reactjs

react-native

react-native-fs

rn-fetch-blob