Question

我正在尝试检查用户中是否存在值。我基本上创建了一个检查来激活或停用按钮，如果值存在。我有一个关注/取消关注系统，但问题是，如果一个用户尚未添加某些值并且用户想要关注它们，则该应用程序将崩溃。所以我只想停用按钮，直到用户添加值然后激活按钮。我一直在尝试这个代码，但没有运气。我想检查他们是否创建了一个值＆＃34; snapchatURL＆＃34;，如果它拥有一个URL并不重要，我只需要知道该值是否存在，无论是否存在URL。

databaseRef.child("Businesses").child(self.otherUser?["uid"] as! String).queryOrdered(byChild: "snapchatURL").observe(.value, with: { (snapshot) in
        if(snapshot.exists()) {
            self.followButton.isEnabled = true
            print("They added their social media")
        } else {
            self.followButton.isEnabled = false
            print("They did not add their social media")
        }
    }) { (error) in
        print(error.localizedDescription)
    }


@IBAction func didTapFollow(_ sender: Any) {

    let followersRef = "followers/\(self.otherUser?["uid"] as! String)/\(self.loggedInUserData?["uid"] as! String)"

    let followingRef = "following/" + (self.loggedInUserData?["uid"] as! String) + "/" + (self.otherUser?["uid"] as! String)


    if(self.followButton.titleLabel?.text == "Favorite") {
        print("follow user")

        let followersData = ["email":self.loggedInUserData?["email"] as! String]
        let followingData = ["businessName":self.otherUser?["businessName"] as! String, "businessStreet":self.otherUser?["businessStreet"] as! String, "businessCity":self.otherUser?["businessCity"] as! String, "businessState":self.otherUser?["businessState"] as! String, "businessZIP":self.otherUser?["businessZIP"] as! String, "businessPhone":self.otherUser?["businessPhone"] as! String, "businessWebsite":self.otherUser?["businessWebsite"] as! String,"businessLatitude":self.otherUser?["businessLatitude"] as! String, "businessLongitude":self.otherUser?["businessLongitude"] as! String, "facebookURL":self.otherUser?["facebookURL"] as! String, "twitterURL":self.otherUser?["twitterURL"] as! String, "instagramURL":self.otherUser?["instagramURL"] as! String, "googleURL":self.otherUser?["googleURL"] as! String, "yelpURL":self.otherUser?["yelpURL"] as! String, "foursquareURL":self.otherUser?["foursquareURL"] as! String, "snapchatURL":self.otherUser?["snapchatURL"] as! String]


        let childUpdates = [followersRef:followersData, followingRef:followingData]
        databaseRef.updateChildValues(childUpdates)

        print("data updated")

    } else {

        let followersRef = "followers/\(self.otherUser?["uid"] as! String)/\(self.loggedInUserData?["uid"] as! String)"
        let followingRef = "following/" + (self.loggedInUserData?["uid"] as! String) + "/" + (self.otherUser?["uid"] as! String)

        let childUpdates = [followingRef:NSNull(),followersRef:NSNull()]
        databaseRef.updateChildValues(childUpdates)
    }
}

Answer 1

我明白了。不必进行任何类型的查询，只需简单的“.child”：）

databaseRef.child("Businesses").child(self.otherUser?["uid"] as! String).child("snapchatURL").observe(.value, with: { (snapshot) in
        if(snapshot.exists()) {
            self.followButton.isEnabled = true
            print("They added their social media")
        } else {
            self.followButton.isEnabled = false
            print("They did not add their social media")
        }
    }) { (error) in
        print(error.localizedDescription)
    }

Swift Firebase检查是否存在价值

1 个答案: