Deleting Realm Object entry if its deleted in API Response - ios

Question

First response in this I get two user i.e abc#gmail.com & xyz#gmail.com
[{
"email": "abc#gmail.com",
"type": "primary_email",
"linked_to": {
"_id": "DAS44564dasdDASd",
"image": null,
"company": null,
"designation": null,
"name": null
},
"active_platforms": [
"asd",
"qwe"
]
},
{
"email": "xyz#gmail.com",
"type": "primary_email",
"linked_to": {
"_id": "DAS44564dasdDASd",
"image": null,
"company": null,
"designation": null,
"name": null
},
"active_platforms": [
"asd",
"qwe"
]
}]
Now if abc#gmail.com is deleted if I do API call again then still I get abc#gmail.com in my object as it is not deleted from my realm. So how to handle such situation ?
// write request result to realm database
let entries = json["data"]
realm.beginWrite()
for (_, subJson) : (String, JSON) in entries {
let entry: AppUsers = Mapper<AppUsers>().map(JSONObject: subJson.dictionaryObject!)!
realm.add(entry, update: true)
}
do {
try realm.commitWrite()
} catch {
}

Answer 1

Update your logic as below. This is one of method to this.
Add one extra bool field to AppUsers model say 'active'. Update your code as below
// write request result to realm database
let entries = json["data"]
realm.beginWrite()
//Fetch all realm AppUsers objects
let allAppUsers = //TODO fetch all AppUsers objects here
for user in allAppUsers {
user.active = false
}
for (_, subJson) : (String, JSON) in entries {
let entry: AppUsers = Mapper<AppUsers>().map(JSONObject: subJson.dictionaryObject!)!
entry.active = true
realm.add(entry, update: true)
}
for user in allAppUsers {
if !user.active {
realm.delete(user)
}
}
do {
try realm.commitWrite()
} catch {
}

Answer 2

This sounds like an issue where the data in your Realm database has become stale as the contents no longer match what is on the server.
The Realm API realm.add(_, update: true) will update any objects that were passed to it, but simply not passing an object does not imply it should be deleted (More that you just didn't want to update it).
There's no way for Realm to automatically know if an object needs to be deleted. You'll need to be in charge of that logic yourself.
Since your mechanism for checking if an object is deleted is via its email address, you could capture the email addresses of each object you've updated, and then delete any other objects whose email address is not in there.
// write request result to realm database
realm.beginWrite()
let entries = json["data"]
var updatedEmails = [String]()
for (_, subJson) : (String, JSON) in entries {
let entry: AppUsers = Mapper<AppUsers>().map(JSONObject: subJson.dictionaryObject!)!
// Save the email we just processed
updatedEmails.append(entry.email)
realm.add(entry, update: true)
}
// Delete all objects not in the updated emails list
let realmEntries = realm.objects(AppUsers.self)
for entry in realmEntries {
if !updatedEmails.contains(entry.email) {
realm.delete(entry)
}
}
do {
try realm.commitWrite()
} catch {
}
If your REST API brings down all of your objects in their complete form each time, a much quicker solution would also be to simply empty the Realm file each time and just add the objects as new objects each time too.