I am trying to post an object with multiple images as an array how do append the images as an array to the formdata

const onSubmit = async (e) => {

    
    const formData = new FormData(); 
    formData.append("image", values.images);
    formData.append("title", values.title);
    formData.append("price", values.price);
    formData.append("quantity", values.quantity);
    formData.append("id", id);

    try {
      const res = await axios.post(
        "//localhost:4000/products/saveProduct",
        formData,
        {
          headers: {
            "Content-Type": "multipart/form-data",
          },
     /////////////
<form onSubmit={handleSubmit(onSubmit)}>
        <div className="custom-file mb-4">
          <input
            type="file"
            className="custom-file-input"
            name="image"
            multiple
            placeholder="choose file"
            onChange={handleChange}
          />
//////
  const handleChange = (e) => {
    const { type, name } = e.target;
    const getValue = () => {
      if (type === "checkbox") {
        return e.target.checked;
      } else if (type === "select-multiple") {
        return Array.from(e.target.selectedOptions).map(
          (option) => option.value
        );
      } else if (type === "file") {
        for (let i = 0; i < e.target.files.length; i++) {
          e.target.files[i].url = URL.createObjectURL(e.target.files[i]);
        }
        return Array.from(e.target.files);
      }
      return e.target.value;
    };

Also When I send this to my back end I am getting to an empty object as the req.body

I am trying to post an object with multiple images as an array how do append the images as an array to the formdata

const onSubmit = async (e) => {

    
    const formData = new FormData(); 
    formData.append("image", values.images);
    formData.append("title", values.title);
    formData.append("price", values.price);
    formData.append("quantity", values.quantity);
    formData.append("id", id);

    try {
      const res = await axios.post(
        "//localhost:4000/products/saveProduct",
        formData,
        {
          headers: {
            "Content-Type": "multipart/form-data",
          },
     /////////////
<form onSubmit={handleSubmit(onSubmit)}>
        <div className="custom-file mb-4">
          <input
            type="file"
            className="custom-file-input"
            name="image"
            multiple
            placeholder="choose file"
            onChange={handleChange}
          />
//////
  const handleChange = (e) => {
    const { type, name } = e.target;
    const getValue = () => {
      if (type === "checkbox") {
        return e.target.checked;
      } else if (type === "select-multiple") {
        return Array.from(e.target.selectedOptions).map(
          (option) => option.value
        );
      } else if (type === "file") {
        for (let i = 0; i < e.target.files.length; i++) {
          e.target.files[i].url = URL.createObjectURL(e.target.files[i]);
        }
        return Array.from(e.target.files);
      }
      return e.target.value;
    };

Also When I send this to my back end I am getting to an empty object as the req.body

• javascript
• reactjs
• axios
• multipartform-data

• how you handleChange when import images? – danhuong Commented Mar 11, 2021 at 14:07
• I just added it now so you can see it – tim Commented Mar 11, 2021 at 14:23

3 Answers 3

You can append all the images to the same key, for example "images". Then you can parse the request body as multipart formdata on the server, and you get an array of files when you access "images".

for (const image of value.images) {
  formData.append("images", image);
}

Although, if I remember correctly. When you only append one file, it isn't going to be parsed into an array on the server.

Another solution is to create (with useRef) or get (with querySelector) a reference to the form element. Then you can create the formData directly from the form element.

const formData = new FormData(myFormElement);

Then you can append the rest of the data that you want to send.

I have laravel backend and what worked for me was to put square brackets after the name of the key

for (const image of value.images) {
  formData.append("images[]",image);
}

for (const image of value.images) {
  formData.append("images",JSON.stringify(image));
}

when pass multiple image make string object using JSON.stringify(Object)