I am trying to upload files from Angular 4 app to a JSON API service that accepts base64 strings as file content.
So what I do is - read the file with FileReader.readAsDataURL
, then when user confirms the upload I will create a JSON request to the API and send the base64
string of the file I got earlier.
This is where the problem starts - as soon as I do something with the "content" (log it, send it, w/e) the request will be send, but its insanely slow, eg 20 seconds for 2MB file.
I have tried:
ArrayBuffer
and manually converting it to base64 @angular/common
but everything leads to the same result.
I know where the problem lies. But why does it happen ? Is it something browser specific or angular specific? Is there a more preferred approach (keep in mind it has to be base64 string)?
Notes:
Code:
This method runs when user adds file to the dropzone:
public onFileChange(files: File[]) : void {
files.forEach((file: File, index: number) => {
const reader = new FileReader;
// UploadedFile is just a simple model that contains filename, size, type and later base64 content
this.uploadedFiles[index] = new UploadedFile(file);
//region reader.onprogress
reader.onprogress = (event: ProgressEvent) => {
if (event.lengthComputable) {
this.uploadedFiles[index].updateProgress(
Math.round((event.loaded * 100) / event.total)
);
}
};
//endregion
//region reader.onloadend
reader.onloadend = (event: ProgressEvent) => {
const target: FileReader = <FileReader>event.target;
const content = target.result.split(',')[1];
this.uploadedFiles[index].contentLoaded(content);
};
//endregion
reader.readAsDataURL(file);
});
}
This method runs when users clicks save button
public upload(uploadedFiles: UploadedFile[]) : Observable<null> {
const body: object = {
files: uploadedFiles.map((uploadedFile) => {
return {
filename: uploadedFile.name,
// SLOWDOWN HAPPENS HERE
content: uploadedFile.content
};
})
};
return this.http.post('file', body)
}
For sending big files to server you should use FormData
to be able to send it as multi-part instead of a single big file.
Something like:
// import {Http, RequestOptions} from '@angular/http'; uploadFileToUrl(files, uploadUrl): Promise<any> { // Note that setting a content-type header // for mutlipart forms breaks some built in // request parsers like multer in express. const options = new RequestOptions(); const formData = new FormData(); // Append files to the virtual form. for (const file of files) { formData.append(file.name, file) } // Send it. return this.http.post(uploadUrl, formData, options); }
Also don't forget to set the header 'Content-Type': undefined
, I've scratched my head over this for hours.
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