New in version 10.2.0.
A Realm dictionary is an implementation of IDictionary that has keys of type String and supports values of any Realm type except collections. To define a dictionary, use a getter-only IDictionary<string, TValue> property, where TValue is any of the supported types.
A dictionary of objects can contain null objects. Likewise, dictionaries of primitive types can also contain null values. If you do not want to allow null values in a dictionary, then either use non-nullable types in the dictionary declaration (for example, use IDictionary<string, double> instead of IDictionary<string, double?>). If you are using the older schema type definition (your classes derive from the RealmObject base class), or you do not have nullability enabled, use the [Required] attribute if the dictionary contains nullable reference types, such as string or byte[].
Realm disallows the use of . or $ characters in map keys. You can use percent encoding and decoding to store a map key that contains one of these disallowed characters.
Local-only realms support collections of nullable (optional) values, but Sync does not.
The following code shows examples of dictionary types:
public partial class Inventory : IRealmObject{ [PrimaryKey] [MapTo("_id")] public string Id { get; set; } public IDictionary<string, Plant?> Plants { get; } public IDictionary<string, bool> BooleansDictionary { get; } public IDictionary<string, int?> NullableIntDictionary { get; } public IDictionary<string, string> RequiredStringsDictionary { get; }}The following code shows how to create, write to, and read from Dictionaries using either a string query (RQL) or LINQ.
var storeInventory = new Inventory(){ Id = ObjectId.GenerateNewId().ToString()};storeInventory.Plants.Add("Petunia", new Plant());storeInventory.NullableIntDictionary.Add("random things", 7);storeInventory.RequiredStringsDictionary.Add("foo", "bar");var storeInventory2 = new Inventory(){ Id = ObjectId.GenerateNewId().ToString()};storeInventory2.RequiredStringsDictionary.Add("foo", "Bar");realm.Write(() =>{ realm.Add(storeInventory); realm.Add(storeInventory2);});var petunias = realm.All<Inventory>() .Filter("Plants.@keys == 'Petunia'");var matchesMoreThanFive = realm.All<Inventory>() .Filter("NullableIntDictionary.@values > 5");var matches = realm.All<Inventory>() .Filter("RequiredStringsDictionary['foo'] CONTAINS[c] 'bar'");var myStoreInventory = realm .All<Inventory>().FirstOrDefault();var petunia = myStoreInventory.Plants.AsRealmQueryable() .Where(p => p.Name == "Petunia");You can use the INotifyCollectionChanged.CollectionChanged event on a dictionary to watch for changes to the collection, and the INotifyPropertyChanged.PropertyChanged event to watch for changes to specific properties in the dictionary.
In the following code example, we have a class with an IDictionary<string, int> property named IntDictionary. We set up event handlers for both the CollectionChanged and PropertyChanged events:
var dictionary = container.IntDictionary.AsRealmCollection();dictionary.CollectionChanged += (sender, e) =>{ Console.WriteLine($"Collection {sender} changed: {e.Action}");};dictionary.PropertyChanged += (sender, e) =>{ Console.WriteLine($"Property changed on {sender}: {e.PropertyName}");};RetroSearch is an open source project built by @garambo | Open a GitHub Issue
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