How to send a file/image from React to node.js server - node.js

Question

I'm trying to send a file/image from React to node.js server with multer. The problem is I can send an image only through Postman but when I'm trying the same in React I'm getting: TypeError: Cannot read property 'path' of undefined. I don't understand whether I should send a file/image in binary or use another format. I've already tried to use reader.readAsDataURL() and reader.readAsBinaryString() but it didn't work.
const multer = require("multer");
const storage = multer.diskStorage({
destination: (req, file, cb) => {
cb(null, "./uploads/");
},
filename: (req, file, cb) => {
cb(null, new Date().toISOString() + file.originalname);
}
});
const fileFilter = (req, file, cb) => {
if (
file.mimetype === "image/jpeg" ||
file.mimetype === "image/png" ||
file.mimetype === "image/jpg"
) {
cb(null, true);
}
cb(null, false);
};
const upload = multer({
storage: storage,
limits: { fileSize: 5000000 },
fileFilter: fileFilter
});
// Create a post
router.post(
"/",
upload.single("image"),
passport.authenticate("jwt", { session: false }),
(req, res) => {
const { errors, isValid } = validationPostInput(req.body);
if (!isValid) {
return res.status(400).json(errors);
}
console.log(req.file);
const newPost = new Post({
text: req.body.text,
theme: req.body.theme,
name: req.body.name,
avatar: req.body.avatar,
image: req.file.path,
user: req.user.id
});
newPost.save().then(post => res.json(post));
}
);
// CREATE A POST
export const createPost = (userInput, history) => dispatch => {
const headers = {
"Content-Type": "form-data"
};
axios
.post("/post", userInput, headers)
.then(res => history.push("/post/all"))
.catch(err =>
dispatch({
type: GET_ERRORS,
payload: err.response.data
})
);
};
import React, { Component } from "react";
import PropTypes from "prop-types";
// import { Link } from "react-router-dom";
import { connect } from "react-redux";
import { createPost } from "../../actions/postActions";
import "./style.css";
class CreatePost extends Component {
state = {
text: "",
theme: "",
image: "",
errors: {}
};
componentWillReceiveProps(nextProps) {
if (nextProps.errors) {
this.setState({ errors: nextProps.errors });
}
}
onSubmit = e => {
e.preventDefault();
const { user } = this.props.auth;
const newPost = {
text: this.state.text,
theme: this.state.theme,
image: this.state.image,
name: user.username,
avatar: user.avatar
};
this.props.createPost(newPost);
};
onChange = e => this.setState({ [e.target.name]: e.target.value });
fileSelectHandler = e => {
const param = e.target.files[0];
let reader = new FileReader();
reader.readAsDataURL(param);
this.setState({
image: reader.result
});
console.log(reader);
};
render() {
const { text, theme, errors } = this.state;
return (
<section className="post">
<form
onSubmit={this.onSubmit}
className="post__form"
action="/post"
method="POST"
encType="multipart/form-data"
>
<div className="post__form--input">
<label>Theme</label>
<input
type="text"
name="theme"
value={theme}
onChange={this.onChange}
/>
{errors && <small>{errors.theme}</small>}
</div>
<div className="post__form--input">
<label>Text</label>
<textarea
type="text"
name="text"
value={text}
onChange={this.onChange}
/>
{errors && <small>{errors.text}</small>}
</div>
<div className="post__form--file">
<label>Add Image</label>
<input
type="file"
name="file"
accept=".png, .jpg"
onChange={this.fileSelectHandler}
/>
</div>
<button type="submit" className="button">
Submit
</button>
</form>
</section>
);
}
}
CreatePost.propTypes = {
errors: PropTypes.object.isRequired
};
const mapStateToProps = state => ({
errors: state.errors,
auth: state.auth
});
export default connect(
mapStateToProps,
{ createPost }
)(CreatePost);

Answer 1

Finally, I found out how to solve that problem.
onSubmit = e => {
e.preventDefault();
const { user } = this.props.auth;
const form = new FormData();
form.append("file", this.state.file);
form.append("theme", this.state.theme);
form.append("text", this.state.text);
form.append("name", user.username);
form.append("avatar", user.avatar);
this.props.createPost(form);
}

Answer 2

You are sending the field name as file:
<input
type="file"
name="file"
accept=".png, .jpg"
onChange={this.fileSelectHandler}
/>
But you are setting the field name as "image" on multer:
upload.single("image")
You need to change it to:
upload.single("file")
The correct syntax is:
.single(fieldname)
Accept a single file with the name fieldname. The single file will be
stored in req.file.