角度2中的图片上传问题：

Question

Image Upload issue in angular 2:

We have a problem with uploading images into mysql as 'blob data' using angular 2.We dont know How to parse image into blob data

image.html:

<input type="file"  class="fileinput btn-primary" name="file" id="file" formControlName="file"
                        title="Browse image" [(ngModel)]="student.file" (change)="onChange($event)" />

image.component.ts:

            file: File;
            onChange(event: EventTarget) {
            let eventObj: MSInputMethodContext = <MSInputMethodContext> event;
            let target: HTMLInputElement = <HTMLInputElement> eventObj.target;
            let files: FileList = target.files;
            this.file = files[0];
            console.log(this.file);

In Json

   Student(
    name: string,
    class:string,
    file: any,
    rollNo: number): Observable<any> {
    let requestData = {
        name: name,
        class: class,
        photo: {
            data: file,
            contentType: "multipart/form-data"
        },
        rollNo: rollNo,
    };
    return this.http.post(this.studentUrl, requestData)
        .map(response => {
            return response;
        });
}

When we run this code it shows following error.

Exception

"Caused by: org.hibernate.TransientPropertyValueException: object references an unsaved transient instance - save the transient instance before flushing

If any plugin or directives for this?

Answer 1

I used below code to solve similar problem

This is my file element in COMPONENTNAME.component.html

<input type="file" (change)="fileChange($event)">

Create fileChange function to your COMPONENT.component.ts

private fileChange(event: any) {
    let reader = new FileReader();
    let imageBlob: any;
    reader.onload = (fileReadEvent: any) => {
        imageBlob = fileReadEvent.target.result;
    };
    reader.readAsDataURL(event.target.files[0]);
}

when you upload image it will call fileChange method and readAsDataURL method will be triggered and imageBlob variable will be having image as blob.

Hope this will solve your problem!!