Firebase函数 - 写入数据库

1 回答

• 2

  // 1: Listen to a write event at "/dir1/{PUSH-ID}/dir2/{MESSAGE-ID}".
  exports.propagateMessages =
    functions.database.ref('/dir1/{PUSH_ID}/dir2/{MESSAGE_ID}')
      .onWrite((change, context) => {
        // Do Nothing when the data is deleted...
        if (!change.after.exists()) {
          // Perhaps you intend to delete from cloned dirs?
          // if so, left as reader's exercise, just follow from below
          return null;
        }
        else {
          let pushId = context.params.PUSH_ID;
          let messageID = context.params.MESSAGE_ID;
  
          let fireDB = change.after.ref.root;
  
          // 2: Read data from a directory at "/dir1/{PUSH-ID}/dir2/dir3".
          return fireDB.child(`/dir1/${pushId}/dir2/dir3`).once('value')
            .then(listenersSnapshot => {
  
              let listener_promises = []; // collection of writes
  
              // 2.5: For each item in "/dir1/{PUSH-ID}/dir2/dir3", get the key.
              listenersSnapshot.forEach(childSnapshot => {
                let child_key = childSnapshot.key;
  
                // 3: For each key, "clone" the data from the original write to "/dir4/{key}/dir5/{MESSAGE-ID}".
                listener_promises.push(
                  fireDB.child(`/dir4/${child_key}/dir5/${messageID}`).set(change.after.val())
                );
              });
  
              // wait on all writes to complete
              return Promise.all(listener_promises);
            })
            .catch(err => {
              console.log(err);
            });
        }
      })
  

  回复于 2024-05-13T11:57:13+08:00