Add values from array into Realm database - ios

Question

I have my Device class defined as such:
class Device: Object {
dynamic var asset_tag = ""
}
I have an array like this ["43", "24", "23", "64"]
and I would like to loop through the array and add each one into the asset_tag attribute of the Device entity in Realm.

Answer 1

To create an array in Realm you use List. According to Realm's docs, List is the container type in Realm used to define to-many relationships. It goes on to say, "Properties of List type defined on Object subclasses must be declared as let and cannot be dynamic." This means you need to define an entirely separate object to create a list in Realm, there are no native types that will allow you to do something like
let assetTagList = List<String>().
You need to create an AssetTags object and make a list of it in your Device object as follows:
class AssetTags: Object {
dynamic var stringValue = ""
}
class Device: Object {
var asset_tags: [String] {
get {
return _assetTags.map { $0.stringValue }
}
set {
_assetTags.removeAll()
_assetTags.append(objectsIn: newValue.map({ AssetTags(value: [$0]) }))
}
}
let _assetTags = List<AssetTags>()
override static func ignoredProperties() -> [String] {
return ["asset_tags"]
}
}
Now you can do this to add asset tags to Device.
//adding asset tags
let realm = try! Realm()
try! realm.write {
let device = Device()
device.asset_tags = ["1", "2"]
realm.add(device)
}
//looking at all device objects and asking for list of asset tags
for thisDevice in realm.objects(Device.self) {
print("\(thisDevice.asset_tags)")
}
SECOND EDIT
This is not the way I would do it but I think this is what you might find easier to understand.
class AssetTags: Object {
dynamic var id = 0
override static func primaryKey() -> String? {
return "id"
}
dynamic var tagValue = ""
}
class Device: Object {
let assetTags = List<AssetTags>()
}
So now Device has a list of asset tags. I added a primary id for Asset Tags because you indicated you might want to add more properties so an id should help make each one unique. It is optional though, so you can remove it if you do not need it.
To add assetTags objects to a Device object in a for-loop style (note: device in this code exampl is the device object you want to save the asset tags to):
var assetTagArray: [String] = ["1", "2"]
let realm = try! Realm()
for assetTag in assetTagArray {
let newAssetTag = AssetTags()
newAssetTag.tagValue = assetTag
newAssetTag.id = (realm.objects(AssetTags.self).max(ofProperty: "id") as Int? ?? 0) + 1
do {
try realm.write {
device?.assetTags.append(newAssetTag)
}
} catch let error as NSError {
print(error.localizedDescription)
return
}
}