Employing Multer and Express in conjunction with TypeScript

Question

Employing Multer and Express in conjunction with TypeScript

Overview

Currently, I am working on a project that involves creating a user-friendly website where individuals can easily upload images. For this particular task, I have employed Node.js, React, Multer, and Typescript.

Issue at Hand

app.post('/admin/uploads', async (req, res) => {
  uploadHandler(req, res, (err) => {
    ...
    if ( req.files.companyImage !== undefined ) {
      ...
    }
    res.sendStatus(201);
  });
});

An error is being highlighted by the TypeScript intellisense tool with regards to the 'companyImage' property within the 'files' object.

The specific error message reads as follows:

Property 'companyImage' does not exist on type '{ [fieldname: string]: File[]; } | File[]'.
Property 'companyImage' does not exist on type '{ [fieldname: string]: File[]; }'.ts(2339)

I find this perplexing since, in my understanding, the 'files' object should have a type of '{ [fieldname: string]: File[]; }'. This suggests that the 'files' object is capable of having properties that are strings.

To verify this hypothesis, I conducted a simple test:

Type myType = {
  [fieldName: string]: number
}

let req: myType = {
  a: 333,
  b: 344
}

console.log(req.a);
console.log(req.c); // The output is 'undefined', yet no errors are shown by intellisense.

Despite my analysis, I am still puzzled by why the 'companyImage' property cannot be present within the 'files' object.

If you could provide some clarification on this matter, it would be greatly appreciated.

node.js typescript express multer

Answer 1

Answer №1

It's uncertain if you have successfully resolved your problem, but I encountered a similar issue and had to explicitly declare the type of my req.files property in TypeScript as follows:

const files = req.files as { [fieldname: string]: Express.Multer.File[] };

It's important to note that when using upload.fields(...), I did not specify that req.files could also be a simple Express.Multer.File[].

Answer 2

It's uncertain if you have successfully resolved your problem, but I encountered a similar issue and had to explicitly declare the type of my req.files property in TypeScript as follows:

const files = req.files as { [fieldname: string]: Express.Multer.File[] };

It's important to note that when using upload.fields(...), I did not specify that req.files could also be a simple Express.Multer.File[].

Answer 3

Answer №2

To utilize typescript effectively, it's recommended to define an interface for files in the following manner:

interface IFile {
  fieldname: string;
  originalname: string;
  encoding: string;
  mimetype: string;
  buffer: Buffer;
  size: number;
}

After defining the interface, you can then assign

const files = req.files as IFile[]

. Ensure to include files: IFile; in the types/express/index.d.ts file like so:

declare global {
  namespace Express {
    interface Request {
      files: IFile;
    }
  }
}

Answer 4

To utilize typescript effectively, it's recommended to define an interface for files in the following manner:

interface IFile {
  fieldname: string;
  originalname: string;
  encoding: string;
  mimetype: string;
  buffer: Buffer;
  size: number;
}

After defining the interface, you can then assign

const files = req.files as IFile[]

. Ensure to include files: IFile; in the types/express/index.d.ts file like so:

declare global {
  namespace Express {
    interface Request {
      files: IFile;
    }
  }
}

Answer 5

Answer №3

On my TypeScript version (^5.2.2), I encountered a similar issue. Although there seems to be no type for Multer, I managed to resolve the problem.

To address this, I defined a namespace in a global type file:

export type IFile = {
  fieldname: string;
  originalname: string;
  encoding: string;
  mimetype: string;
  buffer: Buffer;
  size: number;
};

declare global {
  namespace Express {
    type Request = {
      files: IFile;
    };
  }
}

Next, I utilized the declared type where necessary:

const fileInfo = (req.files as { fileName?: IFile[] })['fileName']?.[0];

In this context, the variable fileName holds the name of your uploaded file.

Answer 6

On my TypeScript version (^5.2.2), I encountered a similar issue. Although there seems to be no type for Multer, I managed to resolve the problem.

To address this, I defined a namespace in a global type file:

export type IFile = {
  fieldname: string;
  originalname: string;
  encoding: string;
  mimetype: string;
  buffer: Buffer;
  size: number;
};

declare global {
  namespace Express {
    type Request = {
      files: IFile;
    };
  }
}

Next, I utilized the declared type where necessary:

const fileInfo = (req.files as { fileName?: IFile[] })['fileName']?.[0];

In this context, the variable fileName holds the name of your uploaded file.

Answer 7

Answer №4

The issue was resolved using the Object.assign(req.files) method, allowing it to be manipulated as an object: console.log(s.image[0].path);

Answer 8

The issue was resolved using the Object.assign(req.files) method, allowing it to be manipulated as an object: console.log(s.image[0].path);

Employing Multer and Express in conjunction with TypeScript

Overview

Issue at Hand

Answer №1

Answer №2

Answer №3

Answer №4

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