How can I remove all JSON objects that have a certain key/value pair from an array of JSON objects? - arrays

Question

I want to filter a dataset this like:
For example here's some fake dataset:
[
{
"name": "Sakura",
"hasChildren": false,
"livesInCity": true,
"pets": [
{
"cats": ["Luna", "Milk"],
"type": "tabby"
}
]
},
{
"name": "Linn",
"hasChildren": false,
"livesInCity": true,
"pets": [
{
"cats": ["Luna"],
"type": "tabby"
}
]
},
{
"name": "Donna",
"hasChildren": false,
"livesInCity": false,
"pets": [
{
"cats": ["Luna", "Milk"],
"type": "tabby"
}
]
},
{
"name": "Tia",
"hasChildren": false,
"livesInCity": false,
"pets": [
{
"cats": ["Luna", "Milk"],
"type": "tuxedo"
}
]
},
{
"name": "Dora",
"hasChildren": false,
"livesInCity": true,
"pets": [
{
"cats": ["Artemis", "Milk"],
"type": "tuxedo"
}
]
}
]
I want to filter out everything that has "livesInCity": false:
[
{
"name": "Sakura",
"hasChildren": false,
"livesInCity": true,
"pets": [
{
"cats": ["Luna", "Milk"],
"type": "tabby"
}
]
},
{
"name": "Linn",
"hasChildren": false,
"livesInCity": true,
"pets": [
{
"cats": ["Luna"],
"type": "tabby"
}
]
},
{
"name": "Dora",
"hasChildren": false,
"livesInCity": true,
"pets": [
{
"cats": ["Artemis", "Milk"],
"type": "tuxedo"
}
]
}
]
How can I do this? Is this possible?
In python I believe it's something like this, but I do not know how to get started in Swift:
people = [person for person in people if person.livesInCity == True]
Also, how can I filter this data set above to look like this - I want to categorize by type in name.
{
"tabby": ["Sakura", "Linn"],
"tuxedo": ["Dora"],
}
Any help will be very appreciated!

Answer 1

As already mentioned in the comments, you can't work directly on JSON objects in Swift. They need to be converted first.
You can parse your JSON to a Swift object and then perform filtering, grouping etc.
struct Person: Codable {
let name: String
let hasChildren: Bool
let livesInCity: Bool
let pets: [Pet]
}
struct Pet: Codable {
let cats: [String]
let type: String
}
let jsonStr = "[{"name": "Sakura", ..." // your JSON string
let jsonData = jsonStr.data(using: .utf8)!
let parsedObjects = try! JSONDecoder().decode([Person].self, from: data)
Then you can filter your parsedObjects:
let filteredObjects = parsedObjects.filter({ person in person.livesInCity == true })
or in shorter (swiftier) version:
let filteredObjects = parsedObjects.filter { $0.livesInCity }
You can also try to group by pet type:
var groupedDict = [String:[String]]()
filteredObjects.forEach{ person in
person.pets.forEach { pet in
if let _ = groupedDict[pet.type] {
groupedDict[pet.type]!.append(person.name)
} else {
groupedDict[pet.type] = [person.name]
}
}
}
print(groupedDict)
//prints ["tabby": ["Sakura", "Linn"], "tuxedo": ["Dora"]]
If at any point you want to convert your objects back to JSON you can use:
let dictData = try! JSONEncoder().encode(groupedDict)
let dictStr = String(data: dictData, encoding: .utf8)!
print(dictStr)
//prints {"tabby":["Sakura","Linn"],"tuxedo":["Dora"]}
Note
For the sake of simplicity I used forced optional unwrapping (!) when decoding/encoding objects. You may want to use do-try-catch instead (to catch errors).