[英]How do I upload a file with the JS fetch API?
I am still trying to wrap my head around it.我仍然试图绕过它。
I can have the user select the file (or even multiple) with the file input:我可以让用户使用文件输入选择文件(甚至多个):
<form>
<div>
<label>Select file to upload</label>
<input type="file">
</div>
<button type="submit">Convert</button>
</form>
I've done it like this:我是这样做的:
var input = document.querySelector('input[type="file"]')
var data = new FormData()
data.append('file', input.files[0])
data.append('user', 'hubot')
fetch('/avatars', {
method: 'POST',
body: data
})
This is a basic example with comments.这是一个带有注释的基本示例。 The upload
function is what you are looking for: upload
功能正是您要找的:
// Select your input type file and store it in a variable
const input = document.getElementById('fileinput');
// This will upload the file after having read it
const upload = (file) => {
fetch('http://www.example.net', { // Your POST endpoint
method: 'POST',
headers: {
// Content-Type may need to be completely **omitted**
// or you may need something
"Content-Type": "You will perhaps need to define a content-type here"
},
body: file // This is your file object
}).then(
response => response.json() // if the response is a JSON object
).then(
success => console.log(success) // Handle the success response object
).catch(
error => console.log(error) // Handle the error response object
);
};
// Event handler executed when a file is selected
const onSelectFile = () => upload(input.files[0]);
// Add a listener on your input
// It will be triggered when a file will be selected
input.addEventListener('change', onSelectFile, false);
An important note for sending Files with Fetch API使用 Fetch API 发送文件的重要说明
One needs to omit content-type
header for the Fetch request.需要省略 Fetch 请求的content-type
标头。 Then the browser will automatically add the Content type
header including the Form Boundary which looks like然后浏览器会自动添加Content type
标题,包括表单边界,看起来像
Content-Type: multipart/form-data; boundary=—-WebKitFormBoundaryfgtsKTYLsT7PNUVD
Form boundary is the delimiter for the form data表单边界是表单数据的分隔符
If you want multiple files, you can use this如果你想要多个文件,你可以使用这个
var input = document.querySelector('input[type="file"]')
var data = new FormData()
for (const file of input.files) {
data.append('files',file,file.name)
}
fetch('/avatars', {
method: 'POST',
body: data
})
To submit a single file, you can simply use the File
object from the input
's .files
array directly as the value of body:
in your fetch()
initializer:要提交单个文件,您可以直接使用input
的.files
数组中的File
对象作为body:
在您的fetch()
初始值设定项中的值:
const myInput = document.getElementById('my-input');
// Later, perhaps in a form 'submit' handler or the input's 'change' handler:
fetch('https://example.com/some_endpoint', {
method: 'POST',
body: myInput.files[0],
});
This works because File
inherits from Blob
, and Blob
is one of the permissible BodyInit
types defined in the Fetch Standard.这是有效的,因为File
继承自Blob
,而Blob
是 Fetch Standard 中定义的允许的BodyInit
类型之一。
The accepted answer here is a bit dated.这里接受的答案有点过时了。 As of April 2020, a recommended approach seen on the MDN website suggests using FormData
and also does not ask to set the content type.截至 2020 年 4 月,在 MDN 网站上看到的推荐方法建议使用FormData
,并且也不要求设置内容类型。 https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch
I'm quoting the code snippet for convenience:为方便起见,我引用了代码片段:
const formData = new FormData();
const fileField = document.querySelector('input[type="file"]');
formData.append('username', 'abc123');
formData.append('avatar', fileField.files[0]);
fetch('https://example.com/profile/avatar', {
method: 'PUT',
body: formData
})
.then((response) => response.json())
.then((result) => {
console.log('Success:', result);
})
.catch((error) => {
console.error('Error:', error);
});
Jumping off from Alex Montoya's approach for multiple file input elements从 Alex Montoya 的多个文件输入元素的方法中跳出来
const inputFiles = document.querySelectorAll('input[type="file"]');
const formData = new FormData();
for (const file of inputFiles) {
formData.append(file.name, file.files[0]);
}
fetch(url, {
method: 'POST',
body: formData })
It would be nice to add php endpoint example.添加 php 端点示例会很好。 So that is js:所以这是js:
const uploadinput = document.querySelector('#uploadinputid');
const uploadBtn = document.querySelector('#uploadBtnid');
uploadBtn.addEventListener('click',uploadFile);
async function uploadFile(){
const formData = new FormData();
formData.append('nameusedinFormData',uploadinput.files[0]);
try{
const response = await fetch('server.php',{
method:'POST',
body:formData
} );
const result = await response.json();
console.log(result);
}catch(e){
console.log(e);
}
}
That is php:那是php:
$file = $_FILES['nameusedinFormData'];
$temp = $file['tmp_name'];
$target_file = './targetfilename.jpg';
move_uploaded_file($_FILES["image"]["tmp_name"], $target_file);
The problem for me was that I was using a response.blob() to populate the form data.我的问题是我正在使用 response.blob() 来填充表单数据。 Apparently you can't do that at least with react native so I ended up using显然你至少不能用 react native 做到这一点,所以我最终使用了
data.append('fileData', {
uri : pickerResponse.uri,
type: pickerResponse.type,
name: pickerResponse.fileName
});
Fetch seems to recognize that format and send the file where the uri is pointing. Fetch 似乎可以识别该格式并将文件发送到 uri 指向的位置。
Here is my code:这是我的代码:
html: html:
const upload = (file) => { console.log(file); fetch('http://localhost:8080/files/uploadFile', { method: 'POST', // headers: { // //"Content-Disposition": "attachment; name='file'; filename='xml2.txt'", // "Content-Type": "multipart/form-data; boundary=BbC04y " //"multipart/mixed;boundary=gc0p4Jq0M2Yt08jU534c0p" // ή // multipart/form-data // }, body: file // This is your file object }).then( response => response.json() // if the response is a JSON object ).then( success => console.log(success) // Handle the success response object ).catch( error => console.log(error) // Handle the error response object ); //cvForm.submit(); }; const onSelectFile = () => upload(uploadCvInput.files[0]); uploadCvInput.addEventListener('change', onSelectFile, false);
<form id="cv_form" style="display: none;" enctype="multipart/form-data"> <input id="uploadCV" type="file" name="file"/> <button type="submit" id="upload_btn">upload</button> </form> <ul class="dropdown-menu"> <li class="nav-item"><a class="nav-link" href="#" id="upload">UPLOAD CV</a></li> <li class="nav-item"><a class="nav-link" href="#" id="download">DOWNLOAD CV</a></li> </ul>
fetch<\/code>
如何使用 HTML5 fetch<\/code>在选择时上传单个文件
<\/h4><label role="button"> Upload a picture <input accept="image\/*" type="file" hidden \/> <\/label><\/code><\/pre> const input = document.querySelector(`input[type="file"]`); function upload() { fetch(uplaodURL, { method: "PUT", body: input.files[0] }); } input.addEventListener("change", upload);<\/code><\/pre>"
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