I'm looking to filter an array of arrays by specific value of one of the keys located within each array. Each nested array is read in from Firestore.
As an object, each nested array would look like this:
struct Video {
var url: String
var submissionDate: Timestamp
var submittingUser: String
}
I'm reading it in like this:
videos = document.get("videos") as? [[String : Any]] ?? nil
So far so good, but when I filter it like this:
filteredVideos = videos.filter { $0[2].contains(self.userIdentification) }
I can't do it without getting the error "Reference to member 'contains' cannot be resolved without a contextual type," an error which I was unable to find any relevant information on SO about.
I have read that some people say "Don't use arrays in Firestore!" but this is a build requirement.
Anyone have any ideas? Basically just need all arrays within the array where userId == submittingUser.
Reference Article:
I tried the answer from here: How to filter out a Array of Array's but no luck for this situation.
It's actually an array of dictionaries, not an array of arrays. All you need to do is construct the right predicate for the filter.
This is basically what your Firestore data looks like:
let videos: [[String: Any]] = [
["url": "http://www...", "submittingUser": "user1"],
["url": "http://www...", "submittingUser": "user2"]
]
This is the user you're looking for:
let userIdentification = "user2"
This is the predicate for the filer:
let filteredVideos = videos.filter { (video) -> Bool in
if let submittingUser = video["submittingUser"] as? String,
submittingUser == userIdentification {
return true
} else {
return false
}
}
You can shorthand this down to a single line if you're okay with force-unwrapping the dictionary (if you're 100% certain every video will have a valid submittingUser value):
let filteredVideos = videos.filter({ $0["submittingUser"] as! String == userIdentification })
Related
I’m trying to display an array of data (stored within a Firestore database field entitled "product") into a UITableViewController. The code I am currently using to try and return the array into my app is below:
if userId == user?.uid {
let group_array = document["product"] as? Array ?? [""]
let productName1 = (group_array) as? String
self.tableViewData =[cellData(opened: false, title: "Item 1", sectionData: [productName1 ?? "No data to display :("])]
}
When I run this, it compiles, however I’m currently getting the following warning message:
Cast from '[String]' to unrelated type 'String' always fails”
This results in no data being returned, and returning nil for productName1, consequently leading to the "No data to display :(" message being shown instead of the data.
Does anyone know which type I would need to assign for the following line to return this data please?
let productName1 = (group_array) as? String
You've defined group_array as an Array. Then you try to cast it to a String. You can't cast an Array (even an array of String objects) to a String.
This line:
let productName1 = (group_array) as? String
Will always fail.
What result are you looking for? The first entry in the array of strings? A string that combines all the elements in the array together?
If you want the first element, use
let productName1 = group_array.first as? string ?? ""
If you want to combine the items, use something like this:
let productNames = (group_array as? [String])?.joined(separator: ", ") ?? ""
By the way, your code would be cleaner if you cast your array to an array of Strings, not just a generic Array (Array of Any)
Change:
let group_array = document["product"] as? Array ?? [""]
To:
let group_array = document["product"] as? [String] ?? [""]
I have array like [[:String:Any]]
I have a value string , and i want to extract the element with that key without looping (one line).
To check if its there I used this :
if(array.map{$0["NAME"] as! String}.contains(value)){
Is there a way to also extract this dictionary within this if statement ?
For that no need to map the array. You can use contains(where:)
if array.contains(where: { $0["name"] as? String == value }) {
print("Exist")
}
If you want object(dictionary) from array also than you can use first(where:)
if let dict = array.first(where: { $0["name"] as? String == value }) {
print(dict)
}
For more on first(where:) check this SO Thread
Ok, I am working in an iMessage app and am trying to parse more than 1 url query item from the selected message here- I have been successful getting/sending just 1 value in a query:
override func willBecomeActive(with conversation: MSConversation) {
// Called when the extension is about to move from the inactive to active state.
// This will happen when the extension is about to present UI.
if(conversation.selectedMessage?.url != nil) //trying to catch error
{
let components = URLComponents(string: (conversation.selectedMessage?.url?.query?.description)!)
//let val = conversation.selectedMessage?.url?.query?.description
if let queryItems = components?.queryItems {
// process the query items here...
let param1 = queryItems.filter({$0.name == "theirScore"}).first
print("***************=> GOT IT ",param1?.value)
}
}
When I just have 1 value, just by printing conversation.selectedMessage?.url?.query?.description I get an optional with that 1 value, which is good. But with multiple I cant find a clean way to get specific values by key.
What is the correct way to parse a URLQueryItem for given keys for iMessage?
When you do conversation.selectedMessage?.url?.query?.description it simply prints out the contents of the query. If you have multiple items then it would appear something like:
item=Item1&part=Part1&story=Story1
You can parse that one manually by splitting the string on "&" and then splitting the contents of the resulting array on "=" to get the individual key value pairs in to a dictionary. Then, you can directly refer to each value by key to get the specific values, something like this:
var dic = [String:String]()
if let txt = url?.query {
let arr = txt.components(separatedBy:"&")
for item in arr {
let arr2 = item.components(separatedBy:"=")
let key = arr2[0]
let val = arr2[1]
dic[key] = val
}
}
print(dic)
The above gives you an easy way to access the values by key. However, that is a bit more verbose. The way you provided in your code, using a filter on the queryItems array, is the more compact solution :) So you already have the easier/compact solution, but if this approach makes better sense to you personally, you can always go this route ...
Also, if the issue is that you have to write the same filtering code multiple times to get a value from the queryItems array, then you can always have a helper method which takes two parameters, the queryItems array and a String parameter (the key) and returns an optional String value (the value matching the key) along the following lines:
func valueFrom(queryItems:[URLQueryItem], key:String) -> String? {
return queryItems.filter({$0.name == key}).first?.value
}
Then your above code would look like:
if let queryItems = components?.queryItems {
// process the query items here...
let param1 = valueFrom(queryItems:queryItems, key:"item")
print("***************=> GOT IT ", param1)
}
You can use iMessageDataKit library. It makes setting and getting data really easy and straightforward like:
let message: MSMessage = MSMessage()
message.md.set(value: 7, forKey: "user_id")
message.md.set(value: "john", forKey: "username")
message.md.set(values: ["joy", "smile"], forKey: "tags")
print(message.md.integer(forKey: "user_id")!)
print(message.md.string(forKey: "username")!)
print(message.md.values(forKey: "tags")!)
(Disclaimer: I'm the author of iMessageDataKit)
I always get the following error when trying to filter my Realm database using NSPredicate:
Property 'text' is not a link in object of type 'getType'
I want to filter my Realm database to show only the items that have some specific text in them. This is what I've tried:
let realm = try! Realm()
let predicate = NSPredicate(format: "typez.text.filter = 'special'")
let filterThis = realm.objects(Publication).filter(predicate)
print(filterThis)
The relevant portion of my model classes is:
class Publication: Object, Mappable {
dynamic var id: Int = 0
var typez = List<getType>()
dynamic var url: String?
}
class getType: Object, Mappable {
dynamic var text: String = ""
}
You mentioned that the relevant portions of you model classes look like so:
class Publication: Object, Mappable {
dynamic var id: Int = 0
var typez = List<getType>()
dynamic var url: String?
}
class getType: Object, Mappable {
dynamic var text: String = ""
}
If I understand you correctly, you want to find Publication instances that have an entry in their typez list with text equal to special. You can express that as:
let realm = try! Realm()
let result = realm.objects(Publication).filter("ANY typez.text = 'special'")
print(result)
I was not liking the accepted answer here because it doesn't actually answer the question... but then it helped me more than I realized. I will now be using closures instead of NSPredicates whenever possible. The actual answer to this question should be a slightly modified version of #NSGangster's answer:
let realm = try! Realm()
//Array of publications
let realmObjects = realm.objects(Publication)
//any publication where .text property == special will be filtered. and filter out empty array
let filterThis = realmObjects.filter({ $0.typez.filter({ $0.text == "special" } != [] ) })
print(filterThis)
.. or something close to that.
But what I was looking for was a bit different. I needed a way to filter on exact words of a multi-word string, and using an NSPredicate with "CONTAINS" would match any containing substring, e.g. a search for "red" would match "fred". Realm doesn't support "LIKE" or regex yet, so using a closure was the only thing I could get to work:
//I was going for a "related terms" result for a dictionary app
let theResults = terms.filter(
{
//Looking for other terms in my collection that contained the
//title of the current term in their definition or more_info strings
$0.definition.components(separatedBy: " ").contains(term.title) ||
$0.more_info.components(separatedBy: " ").contains(term.title)
}
)
With as much of the day as I spent searching, hopefully this helps someone else with a similar issue.
I don't usually use NSPredicate's directly, instead I do an inline predicate closure within the filter paramter.
let realm = try! Realm()
//Array of publications
let realmObjects = realm.objects(Publication)
//any publication where .text property == special will be filtered. and filter out empty array
let filterThis = realmObjects.filter({ $0.getType.filter({ $0.text == "special" } != [] ) })
print(filterThis)
I have an NSCountedSet consisting of String objects, if I iterate over the set and print it out, I see something like this:
for item in countedSet {
print(item)
}
Optional(One)
Optional(Two)
The countedSet is created from an Array of String objects:
let countedSet = NSCountedSet(array: countedArray)
If I print the array I see something like this:
["Optional(One)", "Optional(One)", "Optional(One)", "Optional(Two)", "Optional(Two)"]
Now, I want to use those counted strings to access data in a Dictionary, where the keys are String type and the values have the type [String : AnyObject]. If I print the dictionary, I see all the data.
However, if I use of the objects from the countedSet to access the dictionary, I always get a nil value back:
for item in countedSet {
let key = item as? String
let data = dictionary[key!] // Xcode forced me to unwrap key
print(data)
}
nil
nil
But
let key = "One"
let data = dictionary[key]
gives me the expected data.
What am I missing here, how can I access my data from the countedSet objects?
UPDATE: solved thanks to the comment from Martin R. The String objects were originally NSString objects (obtained from NSScanner), and I was casting them wrongly:
let string = String(originalString)
after I changed it to:
let string = (originalString as! String)
All works fine.