RNFetchBlob.fs.readFile error while ReadStream and Exists works on Android

[easychen]

• please provide the version of installed library and RN project.

"react": "16.0.0-alpha.12",
"react-native": "0.46.4",
"react-native-fetch-blob": "^0.10.6",

• a sample code snippet/repository is very helpful to spotting the problem.

const indexfile = "/data/user/0/com.h2read/files/h2index.json"; 
console.log( "index file= [" + indexfile +"]" );          
            RNFetchBlob.fs.exists(indexfile)
            .then((exist) => {
               
                if(exist)
                {
                    console.log("index file exists");
                    
                    RNFetchBlob.fs.readFile( indexfile ).then( (content) =>{
                        console.log( content );
                    }).catch((err) => { console.log( err ) });
                    
                    
                }
                else
                {
                    console.log("index file NOT exists");
                    //this._append_to_index( null );
                }
            })
            .catch((err) => { console.log( err ) })

cause some errors:

08-01 11:39:54.806 11266 13954 I ReactNativeJS: index file= [/data/user/0/com.h2read/files/h2index.j
son]
08-01 11:39:54.810 11266 13954 I ReactNativeJS: index file exists
08-01 11:39:54.812 11266 13954 I ReactNativeJS: { [Error: Attempt to invoke virtual method 'java.lan
g.String java.lang.String.toLowerCase()' on a null object reference] framesToPop: 1, code: 'ReadFile
 Error' }

But change to ReadStream , it works fine.

const indexfile = "/data/user/0/com.h2read/files/h2index.json"; 
console.log( "index file= [" + indexfile +"]" );

            
            RNFetchBlob.fs.exists(indexfile)
            .then((exist) => {
               
                if(exist)
                {
                    console.log("index file exists");
                    

                    
                    RNFetchBlob.fs.readStream( indexfile )
                    .then((stream) => {
                        let data = ''
                        stream.open()
                        stream.onData((chunk) => {
                            data += chunk
                        })
                        stream.onEnd(() => {
                            console.log(data)
                        })
                    }).catch((err) => { console.log( err ) });
                }
                else
                {
                    console.log("index file NOT exists");

                }
            })
            .catch((err) => { console.log( err ) })

[lll000111]

It seems your readFile is missing the encoding?

https://github.com/wkh237/react-native-fetch-blob/wiki/File-System-Access-API#readfilepath-encodingpromise

If you look at

https://github.com/wkh237/react-native-fetch-blob/blob/master/android/src/main/java/com/RNFetchBlob/RNFetchBlobFS.java#L172

you find a statement

switch (encoding.toLowerCase()) {

right in the Java readFile function.

Method readStream sets a default when the value is missing, see https://github.com/wkh237/react-native-fetch-blob/blob/master/class/RNFetchBlobReadStream.js#L26

Method readFile does not set a default - even if the documentation says so. At least I don't see it anywhere in the sources.

So... documentation error, or missing setting of default value 'utf8' for encoding in readFile?

[easychen]

@lll000111 it works well after add encoding arg , thanks . it seems method readStream not set default encoding value.

content = await RNFetchBlob.fs.readFile( indexfile , 'utf8' );

cc @wkh237

[lll000111]

@wkh237 I was about to add this to my pull request (add a line encoding = encoding || 'utf8' to fs.js function definition for readStream), but I don't actually know if this is intentional (not to have a default for the encoding parameter in readStream).

[lll000111]

I'll close this - there also is #484 and my patch is in the pull request queue for 0.10.9.