我正在编写将firebase中的元素附加到数组以使用文本字段执行简单搜索的代码。
该方法的代码如下：
var filteredEvents = [Event]()
var eventsArray = [Event]()
fileprivate func fetchEvents(){
print("Fetching events....")
//create a reference to the location in the database that you want to pull from and observe the value there
let ref = Database.database().reference().child("events")
// this will retur a snapshot with all the data at that location in the database and cast the results as a dictionary for later use
ref.observe(.value, with: { (snapshot) in
guard let dictionaries = snapshot.value as? [String: Any] else{
return
}
//does the job of sorting dictionary elements by key and value
//displaying the key and each corresponding value
dictionaries.forEach({ (key,value) in
// print(key, value)
//creating an eventDictionary to store the results of previous call
guard let eventDictionary = value as? [String: Any] else{
return
}
//will cast each of the values as an Event based off my included struct
//Make sure to create a model it is the only way to have the data in the format you want for easy access
let events = Event(currentEventKey: key, dictionary:eventDictionary)
// appends that to the dictionary to create the dictionary of events
self.eventsArray.append(events)
})
// will sort the array elements based off the name
self.eventsArray.sort(by: { (event1, event2) -> Bool in
return event1.currentEventName.compare(event2.currentEventName) == .orderedAscending
})
// will again reload the data
self.collectionView?.reloadData()
}) { (err) in
print("Failed to fetch events for search")
}
}
我个人没有想到我可能会举办大量活动的机会。我将无法将所有1000多个事件附加到字典中。那会让我记忆犹新。无论如何，我可以让查询响应文本字段。也有人可以帮助我查询那行来执行此操作但不会破坏我的记忆吗？
"events" : {
"CCDS" : {
"attend:count" : 1,
"event:date" : {
"end:date" : "08/09/2017",
"end:time" : "7:00 PM",
"start:date" : "08/09/2017",
"start:time" : "5:00 PM"
},
"event:description" : "Happy hour is more joyful in the summer thanks to Center City District Sips, which offers discounted drinks and appetizers every Wednesday evening. Catch up with old friends and make a few new ones as Center City’s best bars and restaurants host the summer’s happiest hour every Wednesday from 5-7 p.m. Enjoy $5 cocktails, $4 wine, $3 beers and half-price appetizers at dozens and dozens of bars and restaurants.",
"event:imageURL" :someURL",
"event:location" : {
"event:city" : "Philadelphia",
"event:state" : "PA",
"event:street:address" : "660 Chestnut St",
"event:zip" : 19106
},
"event:name" : "Center City District Sips"
},
"MIA" : {
"attend:count" : 1,
"event:date" : {
"end:date" : "09/03/2017",
"end:time" : "7:00 PM",
"start:date" : "09/02/2017",
"start:time" : "12:00 PM"
},
"event:description" : "Budweiser Made in America Festival is an annual music festival held in Philadelphia and formerly simultaneously held in Los Angeles.Sponsored by Anheuser–Busch and produced by Live Nation, the event features several stages that continuously host live music from a wide range of genres including hip hop, rock, pop, R&B, and EDM.",
"event:imageURL" : "someURL",
"event:location" : {
"event:city" : "Philadelphia",
"event:state" : "PA",
"event:street:address" : "Ben Franklin Parkway",
"event:zip" : 19130
},
"event:name" : "Made In America"
}
},
例如，我想提取有关我使用查询搜索过的事件的所有信息。因此，如果我开始输入美国制造，它将从事件选项卡中提取有关该事件的所有相关信息
这就是我目前所拥有的
fileprivate func fetchEvents(searchString: String){
print("Fetching events....")
//create a reference to the location in the database that you want to pull from and observe the value there
let ref = Database.database().reference().child("events")
// this will retur a snapshot with all the data at that location in the database and cast the results as a dictionary for later use
let query = ref.queryOrdered(byChild: "event:name").queryEqual(toValue: searchString)
print(query)
query.observeSingleEvent(of: .value, with: { (snapshot) in
guard let dictionary = snapshot.value as? [String: Any] else{
print(snapshot.value)
return
}
print(snapshot.value)
}) { (err) in
print("Failed to fetch event data", err)
}
}
返回此
(/events { ep = Made In America; i = "event:name"; sp = Made In America; })
答案 0 :(得分：0)
似乎问题是
"How can I query for a value contained in a child node?"
给出类似于原始
的结构"events" : {
"CCDS" : {
"attend:count" : 1,
"event:imageURL" :"someURL",
"event:name" : "Center City District Sips"
"MIA" : {
"attend:count" : 1,
"event:imageURL" : "someURL",
"event:name" : "Made In America"
Firebase查询会返回您想要的节点。
如果用户输入 Made In America 并点击搜索按钮，则查询将在快照中返回该节点。
let searchString = "Made In America"
let ref = self.ref.child("events")
let query = ref.queryOrdered(byChild: "event:name").queryEqualTo(searchString)
query.observeSingleEvent(of: .value, with: { (snapshot) in
for child in snapshot.children {
let snap = child as! DataSnapshot
let eventDict = snap.value as! [String: Any]
let attendCount = eventDict["attend:count"] as! String
let url = eventDict["event:imageURL"} as! String
}
})
如果你想进行部分字符串匹配，用户可以输入几个字符，例如 Made ，代码类似，但你需要让firebase返回以Made开头的所有匹配...
查询看起来像这样
let startString = "Made"
let endString = "Made" + "\\uf8ff"
let query = ref.queryOrdered(byChild: "event:name")
.queryStarting(atValue: startString)
.queryEnding(atValue: endString")
“\ uf8ff”是Unicode中代码级别非常高的字符 - 因为它包含所有前面的字符。
但是，“即时”查询可能会造成无法响应或缓慢的用户界面，因此不建议这样做。
另一种方法是创建一个单独的节点，其中包含的信息少得多，并包含用户将搜索的元素以及对事件节点的引用。
因此包含所有数据的主节点如下所示
"events" : {
"-uyuh8s8j8jsdas" : {
"event": "CCDS"
"attend:count" : 1,
"event:imageURL" : "someURL",
"-y88jsijsijjids" : {
"event": "MIA"
"attend:count" : 1,
"event:imageURL" : "someURL",
并且'较小'的节点看起来像这样
events_for_searching
-uyuh8s8j8jsdas
event:name: "Center City District Sips"
-y88jsijsijjids
event:name: "Made In America"
有了这个，您可以将events_for_searching中的所有节点加载到一个数组中（然后按用户类型过滤数组），这将使UI非常敏感，当用户选择名称时，您可以使用该键从该节点作为引用，通过observeSingleEvent函数从事件节点加载数据。
修改
在回复评论时，我想在代码中添加更多细节。
这是我的结构
"events" : {
"event_0" : {
"event:name" : "An Event"
},
"event_1" : {
"event:name" : "Made In America"
}
},
以及查询事件的代码：name：Made In America
let searchString = "Made In America"
let ref = self.ref.child("events")
let query = ref.queryOrdered(byChild: "event:name").queryEqual(toValue: searchString)
query.observeSingleEvent(of: .value, with: { (snapshot) in
guard let dictionary = snapshot.value as? [String: Any] else{
print(snapshot.value)
return
}
print(snapshot.value)
}) { (err) in
print("Failed to fetch event data", err)
}
和输出
Optional({
"event_1" = {
"event:name" = "Made In America";
};
})