Failed to load resource: the server responded with a status of 500 (Internal Server Error) this error occurs when I try to upload an image

Question

I am new to MEAN development. I have two input fields and one field with a photo upload button. While I managed to display uploaded photo on the screen, I have a problem uploading it on server. Can anyone help?

I also get this error:

Error: ENOENT: no such file or directory, open 'C:\Something\Something\Something\Practice\finalappbackend\backedn\images\title-i-entered-1623300156286.jpeg'

Here's my code on backend:

app.js

const multer = require("multer");

const MIME_TYPE_MAP = {
  "image/png": "png",
  "image/jpeg": "jpeg",
  "image/jpg": "jpg",
};

const storage = multer.diskStorage({
  destination: (req, file, cb) => {
    const isValid = MIME_TYPE_MAP[file.mimetype];
    let error = new Error("Invalid mime type");
    if (isValid) {
      error = null;
    }
    cb(error, "backedn/images");
  },
  filename: (req, file, cb) => {
    const name = file.originalname.toLowerCase().split(" ").join("-");
    const ext = MIME_TYPE_MAP[file.mimetype];
    cb(null, name + "-" + Date.now() + "." + ext);
  },
});


app.post(
  "/api/posts",
  multer({ storage: storage }).single("image"),
  (req, res, next) => {
    const post = new Post({
      title: req.body.title,
      content: req.body.content,
    });
    console.log(post);
    post.save().then((result) => {
      res.status(201).json({
        message: "Post added successfully",
        postId: result._id,
      });
    });
  }
);

Here's my code on Frontend:

posts.service.ts

addPost(id: string, title: string, content: string, image: File) {
    const postData = new FormData();
    postData.append("title", title);
    postData.append("content", content);
    postData.append("image", image, title);
    this.http
      .post<{ message: string; postId: string }>(
        'http://localhost:3000/api/posts',
        postData
      )
      .subscribe((responseData) => {
        const post: Post = {id: responseData.postId, title: title, content: content}
        this.posts.push(post);
        this.postsUpdated.next([...this.posts]);
      });
  }

post-create.component.ts

imagePreview: string | ArrayBuffer;

onImagePicked(event: Event) {
    const file = (event.target as HTMLInputElement).files[0];
    this.form.patchValue({ image: file });
    this.form.get('image').updateValueAndValidity();
    const reader = new FileReader();
    reader.onload = () => {
      this.imagePreview = reader.result;
    };
    reader.readAsDataURL(file);
  }


onSavePost() {
    if (this.form.invalid) {
      return;
    }
    if (this.mode === 'create') {
      this.postsService.addPost(
        this.form.value.id,
        this.form.value.title,
        this.form.value.content,
        this.form.value.image
      );
    } else {
      this.postsService.updatePost(
        this.postId,
        this.form.value.title,
        this.form.value.content
      );
    }

    this.form.reset();
  }

And post-create.component.html

<div>
      <button mat-stroked-button type="button" (click)="filePicker.click()">
        Pick Image
      </button>
      <input type="file" #filePicker (change)="onImagePicked($event)" />
</div>

Answer 1

Explain

ENOENT stands for: Error No Entry. If you look at the error:

Error: ENOENT: no such file or directory, open 'C:\Something\Something\Something\Practice\finalappbackend\backedn\images\title-i-entered-1623300156286.jpeg'

It means: I cannot open '...finalappbackend\backedn\images' to save the image into, because this directory doesn't exist.

In the multer npm page

Note: You are responsible for creating the directory when providing destination as a function. When passing a string, multer will make sure that the directory is created for you.

Action

Make sure the directory has been created. It could be a typo backedn in the name.