I have the following Realm Objects
class Patient: Object {
#objc dynamic var name: String?
let list = List<RString>()
}
class RString: Object {
#objc dynamic var stringValue: String?
}
I need to filter Patient objects that have an RString component in List with stringValue = "test"
Is something like this possible?
patients = realm?.objects(Patient.self).filter("name = 'name1' AND #% IN list", RString(stringValue: 'test'))
You need to use a SUBQUERY to be able to access the properties of the elements of a List in an NSPredicate. The SUBQUERY will evaluate true for every Patient whose list property includes at least 1 RString element whose stringValue matches the provided String.
patients = realm?.objects(Patient.self).filter("name = %# AND SUBQUERY(list,$element,$element.stringValue == %#).#count>0", "name1", "test")
Related
I'm trying to query multiple objects from Realm using a List of Primary Key Strings. I know I can do this using a for..in loop but I'd rather use a filter if possible.
primaryKeyArray contains a number of Strings
class Item : Object {
#objc dynamic var itemKey = NSUUID().uuidString
}
var primaryKeyArray : List<String>?
//Assume Realm DB already contains multiple Item Objects
//primaryKeyArray contains "key1", "key2", "key3", etc..
let predicate = NSPredicate(format: "itemKey == %#", primaryKeyArray)
let items = realm.objects(Item.self).filter(predicate)
I know the problem is with my predicate format. Not sure whether to use some form of CONTAINS or what? Any help with the predicate syntax would be greatly appreciated!
I think you are asking how to query Realm for items that have keys that match a set of keys in an array.
So given a DogClass Realm Object
class DogClass: Object {
#objc dynamic var dog_id = NSUUID().uuidString
#objc dynamic var dog_name = ""
override static func primaryKey() -> String? {
return "dog_id"
}
}
and suppose we know we want to retrieve three dogs that match some given primary keys
let keysToMatch = ["302AC133-3980-41F3-95E8-D3E7F639B769", "54ECC485-4910-44E5-98B9-0712BB99783E", "71FE403B-30CD-4E6C-B88A-D6FDBB08C509"]
let dogResults = realm.objects(DogClass.self).filter("dog_id IN %#", keysToMatch)
for dog in dogResults {
print(dog.dog_id, dog.dog_name)
}
Note the use of IN in the filter, which will match any dogs with id's in the given array.
You can also pass in a Realm List Object instead of a Swift array and get the same result.
let listOfKeysToMatch = List<String>()
listOfKeysToMatch.append("302AC133-3980-41F3-95E8-D3E7F639B769")
listOfKeysToMatch.append("54ECC485-4910-44E5-98B9-0712BB99783E")
listOfKeysToMatch.append("71FE403B-30CD-4E6C-B88A-D6FDBB08C509")
let dogResults2 = realm.objects(DogClass.self).filter("dog_id in %#", listOfKeysToMatch)
for dog in dogResults2 {
print(dog.dog_id, dog.dog_name)
}
let predicate = NSPredicate(format: "itemKey IN %#", primaryKeyArray)
This is how my Realm objects look:
class Restaurant: Object {
#objc dynamic var name: String? = nil
let meals = List<Meal>()
}
class Meal: Object {
#objc dynamic var mealName: String? = nil
let tag = RealmOptional<Int>()
}
I'm trying to fetch all meals that have some tags (I know I can filter all Realm objects of type Meal for specific tags), but the goal is to fetch all Restaurant objects and filter it's Meal child objects based on tag values.
I tried filtering like this:
restaurants = realm.objects(Restaurant.self).filter("meals.#tags IN %#", selectedTags)
but this won't work. Is there a way to filter results based on values in child object list?
To clarify the question, this is an example how filtering should work
for selectedTags = [1, 2, 3]
This is the whole Restaurant model that is saved in Realm.
[Restaurant {
name = "Foo"
meals = [
Meal {
mealName = "Meal 1"
tag = 1
},
Meal {
mealName = "Meal 2"
tag = 2
},
Meal {
mealName = "Meal 7"
tag = 7
}
]
}]
Filtering should return this:
[Restaurant {
name = "Foo"
meals = [
Meal {
mealName = "Meal 1"
tag = 1
},
Meal {
mealName = "Meal 2"
tag = 2
}
]
}]
Here's one possible solution - add a reverse refererence to the restaurant for each meal object
class Restaurant: Object {
#objc dynamic var name: String? = nil
let meals = List<Meal>()
}
class Meal: Object {
#objc dynamic var mealName: String? = nil
let tag = RealmOptional<Int>()
#objc dynamic var restaurant: Restaurant? //Add this
}
then query the meals for that restaurant with the tags you want.
let results = realm.objects(Meal.self).filter("restaurant.name == %# AND tag IN %#", "Foo", [1,2])
LinkingObjects could also be leveraged but it depends on what kind of queries will be needed and what the relationships are between Restaurants and Meals - I am assuming 1-Many in this case.
if you want ALL restaurants, then LinkingObjects is the way to go.
Edit:
Thought of another solution. This will work without adding a reference or an inverse relationship and will return an array of restaurants that have meals with the selected tags.
let selectedTags = [1,2]
let results = realm.objects(Restaurant.self).filter( {
for meal in $0.meals {
if let thisTag = meal.tag.value { //optional so safely unwrap it
if selectedTags.contains(thisTag) {
return true //the tag for this meal was in the list, return true
}
} else {
return false //tag was nil so return false
}
}
return false
})
In short, you cannot do what you are asking. Not within a Realm query (and therefore benefit from update notifications if that is important) at least. No doubt you can make some kind of structure containing what you want though via non-Realm filtering.
To better answer, let's first consider what you're trying to produce as a query result. As you say, your attempt above won't work. But you're trying to filter Restaurants by having some Meals matching some criteria; this is probably achievable, but your resulting query on Restaurant type would then produce a list of Restaurants. Each restaurant would still have a natural property of all its Meals, and would require the same filter applied again to the meals.
It makes sense though to add a function (if you need the search criteria to be dynamic, use a computed property if the filter is always the same tags) to the Restaurant class that produces a view of its Meals matching your criteria.
e.g.
extension Restaurant
{
var importantMeals : Results<Meal>
{
return meals.filter(...)
}
}
So I think there are two options.
Iterate through all Restaurant objects, and add it to a data structure of your own (Set or array) if its importantMeals property is not empty. Then use the same property to produce the meal list when needed. Or you could use a non-Realm filter to produce that query for you. E.g. realm.objects(Restaurant.self).compactMap {$0}.filter { !$0.importantMeals.isEmpty }
Alternatively, filter all Meals according to your criteria (realm.objects(Meal.self).filter(...)). You could then add a LinkingObjects property to your Meal class to make the Set of Restaurants with relevant Meals.
The correct approach will depend on how you want to use the results, but I'd suggest approach 1 will see you right. Note that you might want to sort the results produced by queries before using if order is of any importance to you (e.g. for displaying in UITableView) as there is no guarantee that the order of objects will be the same for each query performed.
I have made a struct in which I'm passing my data. The data is in an array. I'm running a for loop to get the value out from it but I'm not getting full values. Suppose there is 5.0 value in an array when the loop runs. It first shows me 5, then ., and then 0. I want it to give 5.0 to me rather than seperate values.
My loop is this:
for price in ItemDataSource.sharedInstance.items[indexPath.row].price! {
print(price)
}
It shows this in console:
This is my class for Items:
class Item : NSObject {
var name : String?
var price : String?
var itemDdescription : String?
}
class ItemDataSource : NSObject {
var items = [Item]()
static let sharedInstance = ItemDataSource()
private override init() {}
}
Here I'm passing my values to it:
let item = Item()
item.name = itemName
item.price = String(result)
item.itemDdescription = String(describing: description)
ItemDataSource.sharedInstance.items.append(item)
Explanation:
ItemDataSource.sharedInstance.items[indexPath.row].price! is a String, iterating over it means to iterate over the characters that are in it. So if the `ItemDataSource.sharedInstance.items[indexPath.row].price!" is "5.0", it will print "5", "." and then "0".
To get the price for the given row, just use
let price = ItemDataSource.sharedInstance.items[indexPath.row].price!
as #John Ottenlips suggested.
Your loop may be unnecessary. indexPath.row will increase and allow you to iterate through your items in this delegate method. If you are just trying to get one price per cell try
let price = ItemDataSource.sharedInstance.items[indexPath.row].price!
print(price)
A general code smell is having a for loop inside a method you are returning a cell in.
Wondering if anyone have faced & solved this issue:
Description
I have 2 Classes called Person & Dog where a person can have more than one dog.
class Dog: Object {
dynamic var name = ""
dynamic var age = 0
}
class Person: Object {
dynamic var name = ""
dynamic var picture: NSData? = nil // optionals supported
let dogs = List<Dog>()
}
According to my requirement, I need to fetch all objects from person.name == "ABC" & apply sort all dogs by Name.
Snippet:
let realm = try! Realm()
let result = realm.objects(Person.self).filter("name == %#","ABC").sorted(property : "name")
From the above snippet, sorting is done based on the person Name not on the dog's Name.
How to create a filter & sort the list by dog name?
realm.objects(Person.self) returns Results<Person>. Calling sorted() to Results<Person> means sort Person. If you'd like to sort dogs, you can retrieve element of person first, (e.g. let person = result[0]), then retrieve dogs property, call sorted() method to it.
let people = realm.objects(Person.self).filter("name == %#","ABC")
let person = people.first!
let sortedDogs = person.dogs.sorted(property : "name")
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)