用Parse查询和更新投票？
我正在尝试建立一个投票系统Parse作为我的后端。
我想使用向左和向右滑动作为投票方法，我使用query.getObjectInBackgroundWithID，以便我可以将投票计数更新到我的后端。
我在查询它时遇到了麻烦，并且还保留了后面的投票并将其附加到单元格中，以便在tableview单元格上添加投票计数。
在我的查询日志中继续收到此错误：
没有与查询匹配的结果（代码：101，版本：1.7.2）
我该如何纠正？另外，在我让查询工作并更新后端后，如何使投票系统工作？
到目前为止，这是我的代码：
import UIKit
import Parse
class HomePage: UITableViewController {
let post = PFObject(className: "Post")
var images = [UIImage]()
var titles = [String]()
var imageFile = [PFFile]()
var voteCounter = 0
var count = [Int]()
override func viewDidLoad() {
super.viewDidLoad()
println(PFUser.currentUser())
var query = PFQuery(className:"Post")
query.orderByDescending("createdAt")
query.limit = 15
query.findObjectsInBackgroundWithBlock {(objects: [AnyObject]?, error: NSError?) -> Void in
if error == nil {
println("Successfully retrieved \(objects!.count) scores.")
println(objects!)
if let objects = objects as? [PFObject] {
for object in objects {
if let title = object["Title"] as? String {
self.titles.append(title)
}
if let imgFile = object["imageFile"] as? PFFile {
self.imageFile.append(imgFile)
}
if let voteCounter = object["count"] as? Int {
self.count.append(voteCounter)
}
self.tableView.reloadData()
}
} else {
// Log details of the failure
println(error)
}
}
}
}
/* println("Successfully retrieved \(objects!.count) scores.")
for object in objects! {
self.titles.append(object["Title"] as! String)
self.imageFile.append(object["imageFile"] as! PFFile)
self.tableView.reloadData()
}*/
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return titles.count
}
override func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
return 500
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
var myCell:cell = self.tableView.dequeueReusableCellWithIdentifier("myCell") as! cell
myCell.rank.text = "21"
myCell.votes.text = "\(count)"
myCell.postDescription.text = titles[indexPath.row]
imageFile[indexPath.row].getDataInBackgroundWithBlock { (data, error) -> Void in
if let downloadedImage = UIImage(data: data!) {
myCell.postedImage.image = downloadedImage
}
}
var swipeRight = UISwipeGestureRecognizer(target: self, action: "respondToSwipeGesture:")
swipeRight.direction = UISwipeGestureRecognizerDirection.Right
myCell.postedImage.userInteractionEnabled = true;
myCell.postedImage.addGestureRecognizer(swipeRight)
var swipeLeft = UISwipeGestureRecognizer(target: self, action: "respondToSwipeGesture:")
swipeRight.direction = UISwipeGestureRecognizerDirection.Left
myCell.postedImage.userInteractionEnabled = true;
myCell.postedImage.addGestureRecognizer(swipeLeft)
这是我收到错误的查询：
var query = PFQuery(className:"Post")
query.getObjectInBackgroundWithId("count") {
(Post: PFObject?, error: NSError?) -> Void in
if error != nil {
println(error)
} else if let Post = Post {
Post["count"] = self.voteCounter
Post.saveInBackground()
}
}
return myCell
}
func respondToSwipeGesture(gesture: UIGestureRecognizer) {
if let swipeGesture = gesture as? UISwipeGestureRecognizer {
switch swipeGesture.direction {
case UISwipeGestureRecognizerDirection.Right:
voteCounter += 1
println("Swiped right")
case UISwipeGestureRecognizerDirection.Left:
voteCounter -= 1
println("Swiped Left")
default:
break
}
}
}
}
这也是我的Parse后端：
我现在添加了新代码
import UIKit
import Parse
class HomePage: UITableViewController {
let post = PFObject(className: "Post")
var images = [UIImage]()
var titles = [String]()
var imageFile = [PFFile]()
var votingObjects: [PFObject] = []
override func viewDidLoad() {
super.viewDidLoad()
println(PFUser.currentUser())
println(PFUser.currentUser())
var query = PFQuery(className:"Post")
query.orderByDescending("createdAt")
query.limit = 15
query.findObjectsInBackgroundWithBlock {
(objects: [AnyObject]?, error: NSError?) -> Void in
if error == nil {
println("Successfully retrieved \(objects!.count) scores.")
println(objects!)
for objectRaw in objects! {
let object = objectRaw as! PFObject
self.votingObjects.append(object)
// Adding them to the array
if let title = object["Title"] as? String {
self.titles.append(title)
}
if let imgFile = object["imageFile"] as? PFFile {
self.imageFile.append(imgFile)
}
}
dispatch_async(dispatch_get_main_queue(), {
self.tableView.reloadData()
// Updating the tableView on the main thread - important. Do some research on Grand Central Dispatch :)
})
} else {
println(error)
// Error
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return titles.count
}
override func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
return 500
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
var myCell:cell = self.tableView.dequeueReusableCellWithIdentifier("myCell") as! cell
myCell.rank.text = "21"
我无法弄清楚myCell.votes.text的正确代码是什么=
myCell.votes.text = votingObjects[indexPath.row]["count"] as? String
myCell.postDescription.text = titles[indexPath.row]
imageFile[indexPath.row].getDataInBackgroundWithBlock { (data, error) -> Void in
if let downloadedImage = UIImage(data: data!) {
myCell.postedImage.image = downloadedImage
}
}
var swipeRight = UISwipeGestureRecognizer(target: self, action: "respondToSwipeGesture:")
swipeRight.direction = UISwipeGestureRecognizerDirection.Right
myCell.postedImage.userInteractionEnabled = true;
myCell.postedImage.addGestureRecognizer(swipeRight)
var swipeLeft = UISwipeGestureRecognizer(target: self, action: "respondToSwipeGesture:")
swipeRight.direction = UISwipeGestureRecognizerDirection.Left
myCell.postedImage.userInteractionEnabled = true;
myCell.postedImage.addGestureRecognizer(swipeLeft)
return myCell
}
在这里遇到问题：
func respondToSwipeGesture(gesture: UIGestureRecognizer) {
if let swipeGesture = gesture as? UISwipeGestureRecognizer {
switch swipeGesture.direction {
case UISwipeGestureRecognizerDirection.Right:
updateVote(true, objectId: String())
println("Swiped right")
case UISwipeGestureRecognizerDirection.Left:
updateVote(false, objectId: String())
println("Swiped Left")
default:
break
}
}
}
func updateVote(increment: Bool, objectId : String) {
// Create a pointer to an object of class Posts with id 'objectId'
var object = PFObject(withoutDataWithClassName: "Post", objectId: objectId)
// Increment the current value of the quantity key by 1
if increment == true {
object.incrementKey("count", byAmount: 1)
} else {
object.incrementKey("count", byAmount: -1)
}
// Save
object.saveInBackgroundWithBlock(nil)
}
}
但是每当我滑动并启动手势识别器时，我都会一直收到无法更新的错误，而无需特定的objectId。我也无法弄清楚如何在我的单元格中显示投票
1 个答案:
答案 0 :(得分：1)
看起来您正在查询Parse数据库以查找不存在的objectID。这是因为当您收到对象时，属性＆＃34; count＆＃34;是正确的投票数...但是当你查询一个对象时，你正在使用＆＃34; count＆＃34;作为显然不会起作用的objectID。您使用变量计数的想法也不起作用。
我建议您稍微调整一下结构。
从初始查询接收对象时，将它们存储在Parse Objects数组中。这样，您可以保留所有信息，更新它们会更容易。还将提供一个属性object.objectId，它是一个String，这是再次查询db时所需要的。
另一个提示是Parse在处理类型number
此外，在处理后台线程时，您应该使用GCD在主线程上进行任何UI调用。
代码：
初始查询 -
var votingObjects: [PFObject] = []
override func viewDidLoad() {
super.viewDidLoad()
println(PFUser.currentUser())
var query = PFQuery(className:"Post")
query.orderByDescending("createdAt")
query.limit = 15
query.findObjectsInBackgroundWithBlock {
(objects: [AnyObject]!, error: NSError!) -> Void in
if error == nil {
println("Successfully retrieved \(objects!.count) scores.")
println(objects!)
for objectRaw in objects {
let object = objectRaw as! PFObject
self.votingObjects.append(object) // Adding them to the array
}
dispatch_async(dispatch_get_main_queue(), {
self.tableView.reloadData() // Updating the tableView on the main thread - important. Do some research on Grand Central Dispatch :)
})
} else {
// Error
}
}
}
// Pass true if you want to upvote or false if downvote
func updateVote(increment: Bool, objectId : String) {
// Create a pointer to an object of class Posts with id 'objectId'
var object = PFObject(withoutDataWithClassName: "Posts", objectId: objectId)
// Increment the current value of the quantity key by 1
if increment == true {
object.incrementKey("count", byAmount: 1)
} else {
object.incrementKey("count", byAmount: -1)
}
// Save
object.saveInBackgroundWithBlock(nil)
}
}
你的tableView函数现在都将链接到数组..
numberOfRows只会使用votingObjects.count
TitleForRow将使用votingObject[indexPath.row]["Title"]! // Should be 'title'
每当您想要引用投票对象ID时，只需使用votingObject[index].objectId
希望我没有错过任何事情：）
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