如何将Firebase中的节点（对象）复制到另一个节点？

Question

我在Firebase中有一个名为Events的节点。它由子对象组成，如：address,description,longitude，latitude。在用户删除事件节点之前，我想将其复制到同一个数据库中，并将其复制到名为eventsDeleted的节点中。

这是删除节点的代码：

removeEvent(eventId, groupId) { 

    return new Promise((resolve, reject)=> { 

    this.eventRef.child(groupId).child(eventId).remove(); 
    resolve(); 

    }); 

} 

这是创建的节点处的代码：

addEvent(data:any) { 
    console.log('Form data', data.group); 

    let localEventRef = firebase.database().ref('events').child(data.group.split(',')[1]); 
    let storageRef = firebase.storage().ref(); 
    let file = data.image; 
    let uploadTask = storageRef.child('eventImages/' + UuidGenerator.generateUUID()).put(file); 
    uploadTask.on('state_changed', function (snapshot) { 

    }, function (error) { 
     // Handle unsuccessful uploads 
     console.error(error); 
    }, function() { 
     // Handle successful uploads on complete 
     let downloadURL = uploadTask.snapshot.downloadURL; 
     let keyOfNewEvent = localEventRef.push(
      new Event(
       null, 
       firebase.app().auth().currentUser.uid, 

       data.description, 


       data.location.address, 
       0 

      ) 
     ).key; 
     localEventRef.child(keyOfNewEvent).update({eventId: keyOfNewEvent}); 
    }); 


} 

没关系的代码上传的图像。我只需要一种方法来复制整个节点，然后将其粘贴到数据库的某个位置。提前致谢。

Answer 1

当用户单击删除时，请确保获取要删除的对象，如果要查询数据库中的该对象，则可以使用.once来检索对象，否则您可以直接跳转到removeEvent函数。

localEventRef.child(keyOfEvent).once("value", function(snapshot) { 
//one data is returned, you can then call the removeEvent fn 

    let eventToBeRemoved = snapshot.val(); 
    //assuming you have the eventid, groupid then. 
    removeEvent(eventId, groupId, eventToBeRemoved); 
}); 

removeEvent(eventId, groupId, eventObjectToBeRemoved) { 
//firebase 3.x comes with a promise method 

    firebase.database().ref('eventsDeleted/' + groupId + '/' + eventId) 
     .set({...eventObjectToBeRemoved}) 
     .then(function() { 
     eventRef.child(groupId).child(eventId).remove();//you can now remove 
     }) 
     .catch(function (error) { 
     console.error("error occured trying to add to deletedEvents", error); 
     }); 
    }); 
}