javascript - 在Firebase存储上载完成后，如何获取下载URL

图片上传完成后，我想获取下载URL，然后将downloadURL设置为我的newAds.picLink（object.property），但是在此代码中，因为上传正在进行中

newAds.update({ picLink: downloadURL });

被调用，由于downloadURL当前不可用且正在进行中，因此会引发错误。我已通过将setTimeOut设置为8秒来解决此问题，该方法允许图像首先完全上传，然后接收到downloadURL，但这是不正确的。

图片完全上传后，如何创建一个正确的回调来设置newAds.picLink = downloadURL？

 addSubmitted.addEventListener('click', e => {
 const newAds = _db.ref(userID).push();
 const newAd = {
 };

const ref = firebase.storage().ref();
const file = $('#exampleInputFile').get(0).files[0];
const name = (+new Date() + '-' + file.name);
const task = ref.child(name).put(file, {contentType: file.type});

function abc() {
    task.snapshot.ref.getDownloadURL().then((downloadURL) => {
        console.log('File available at', downloadURL);
        console.log(downloadURL);
        newAds.update({ picLink: downloadURL });
    });

    task.catch(error => {
        // Use to signal error if something goes wrong.
        console.log(`Failed to upload file and get link - ${error}`);
    });
}

setTimeout(abc,8000);

最佳答案

从Firebase documentation on uploading a file：

var uploadTask = storageRef.child('images/rivers.jpg').put(file);

// Register three observers:
// 1. 'state_changed' observer, called any time the state changes
// 2. Error observer, called on failure
// 3. Completion observer, called on successful completion
uploadTask.on('state_changed', function(snapshot){
  // Observe state change events such as progress, pause, and resume
  // Get task progress, including the number of bytes uploaded and the total number of bytes to be uploaded
  var progress = (snapshot.bytesTransferred / snapshot.totalBytes) * 100;
  console.log('Upload is ' + progress + '% done');
  switch (snapshot.state) {
    case firebase.storage.TaskState.PAUSED: // or 'paused'
      console.log('Upload is paused');
      break;
    case firebase.storage.TaskState.RUNNING: // or 'running'
      console.log('Upload is running');
      break;
  }
}, function(error) {
  // Handle unsuccessful uploads
}, function() {
  // Handle successful uploads on complete
  // For instance, get the download URL: https://firebasestorage.googleapis.com/...
  uploadTask.snapshot.ref.getDownloadURL().then(function(downloadURL) {
    console.log('File available at', downloadURL);
  });
});

因此，这注册了一个state_changed观察者。上传完成后，这将调用StorageReference.getDownloadURL()获取下载URL。

关于javascript - 在Firebase存储上载完成后，如何获取下载URL，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/51463596/