Class Realm

A Realm instance (also referred to as a Realm) represents a Realm database.

Inheritance

Object

Realm

Implements

IDisposable

Namespace: Realms

Assembly: Realm.dll

Syntax

public class Realm : IDisposable

Remarks

Warning: Non-frozen Realm instances are not thread safe and can not be shared across threads. You must call GetInstance(RealmConfigurationBase) on each thread in which you want to interact with the Realm.

Properties

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Config

Gets the RealmConfigurationBase that controls this realm's path and other settings.

Declaration

public RealmConfigurationBase Config { get; }

Property Value

Type	Description
RealmConfigurationBase	The Realm's configuration.

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IsClosed

Gets a value indicating whether the instance has been closed via Dispose(). If true, you should not call methods on that instance.

Declaration

public bool IsClosed { get; }

Property Value

Type	Description
Boolean	`true` if closed, `false` otherwise.

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IsFrozen

Gets a value indicating whether this Realm is frozen. Frozen Realms are immutable and will not update when writes are made to the database. Unlike live Realms, frozen Realms can be used across threads.

Declaration

public bool IsFrozen { get; }

Property Value

Type	Description
Boolean

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IsInTransaction

Gets a value indicating whether there is an active Transaction is in transaction.

Declaration

public bool IsInTransaction { get; }

Property Value

Type	Description
Boolean	`true` if is in transaction; otherwise, `false`.

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Schema

Gets the RealmSchema instance that describes all the types that can be stored in this Realm.

Declaration

public RealmSchema Schema { get; }

Property Value

Type	Description
RealmSchema	The Schema of the Realm.

Methods

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Add(RealmObject, Boolean)

This Realm will start managing a RealmObject which has been created as a standalone object.

Declaration

public RealmObject Add(RealmObject obj, bool update = false)

Parameters

Type	Name	Description
RealmObject	obj	Must be a standalone object, `null` not allowed.
Boolean	update	If `true`, and an object with the same primary key already exists, performs an update.

Returns

Type	Description
RealmObject	The passed object.

Remarks

If the object is already managed by this Realm, this method does nothing. This method modifies the object in-place, meaning that after it has run, obj will be managed. Cyclic graphs (Parent has Child that has a Parent) will result in undefined behavior. You have to break the cycle manually and assign relationships after all object have been managed.

Exceptions

Type	Condition
RealmInvalidTransactionException	If you invoke this when there is no write Transaction active on the Realm.
RealmObjectManagedByAnotherRealmException	You can't manage an object with more than one Realm.

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Add<T>(T, Boolean)

This Realm will start managing a RealmObject which has been created as a standalone object.

Declaration

public T Add<T>(T obj, bool update = false)

    where T : RealmObject

Parameters

Type	Name	Description
T	obj	Must be a standalone object, `null` not allowed.
Boolean	update	If `true`, and an object with the same primary key already exists, performs an update.

Returns

Type	Description
T	The passed object, so that you can write `var person = realm.Add(new Person { Id = 1 });`.

Type Parameters

Name	Description
T	The Type T must not only be a RealmObject but also have been processed by the Fody weaver, so it has persistent properties.

Remarks

If the object is already managed by this Realm, this method does nothing. This method modifies the object in-place, meaning that after it has run, obj will be managed. Returning it is just meant as a convenience to enable fluent syntax scenarios. Cyclic graphs (Parent has Child that has a Parent) will result in undefined behavior. You have to break the cycle manually and assign relationships after all object have been managed.

Exceptions

Type	Condition
RealmInvalidTransactionException	If you invoke this when there is no write Transaction active on the Realm.
RealmObjectManagedByAnotherRealmException	You can't manage an object with more than one Realm.

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All(String)

Get a view of all the objects of a particular type.

Declaration

public IQueryable<dynamic> All(string className)

Parameters

Type	Name	Description
String	className	The type of the objects as defined in the schema.

Returns

Type	Description
IQueryable<Object>	A queryable collection that without further filtering, allows iterating all objects of className, in this realm.

Remarks

Because the objects inside the view are accessed dynamically, the view cannot be queried into using LINQ or other expression predicates.

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All<T>()

Extract an iterable set of objects for direct use or further query.

Declaration

public IQueryable<T> All<T>()

    where T : RealmObject

Returns

Type	Description
IQueryable<T>	A queryable collection that without further filtering, allows iterating all objects of class T, in this Realm.

Type Parameters

Name	Description
T	The Type T must be a RealmObject.

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BeginWrite()

Factory for a write Transaction. Essential object to create scope for updates.

Declaration

public Transaction BeginWrite()

Returns

Type	Description
Transaction	A transaction in write mode, which is required for any creation or modification of objects persisted in a Realm.

Examples

using (var trans = realm.BeginWrite())
{
    realm.Add(new Dog
    {
        Name = "Rex"
    });
    trans.Commit();
}

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Compact(RealmConfigurationBase)

Compacts a Realm file. A Realm file usually contains free/unused space. This method removes this free space and the file size is thereby reduced. Objects within the Realm file are untouched.

Declaration

public static bool Compact(RealmConfigurationBase config = null)

Parameters

Type	Name	Description
RealmConfigurationBase	config	Optional configuration.

Returns

Type	Description
Boolean	`true` if successful, `false` if any file operation failed.

Remarks

The realm file must not be open on other threads. The file system should have free space for at least a copy of the Realm file. This method must not be called inside a transaction. The Realm file is left untouched if any file operation fails.

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CreateObject(String, Object)

Factory for a managed object in a realm. Only valid within a write Transaction.

Declaration

public dynamic CreateObject(string className, object primaryKey)

Parameters

Type	Name	Description
String	className	The type of object to create as defined in the schema.
Object	primaryKey	The primary key of object to be created. If the object doesn't have primary key defined, this argument is ignored.

Returns

Type	Description
Object	A dynamically-accessed Realm object.

Remarks

WARNING: if the dynamic object has a PrimaryKey then that must be the first property set otherwise other property changes may be lost.

If the realm instance has been created from an un-typed schema (such as when migrating from an older version of a realm) the returned object will be purely dynamic. If the realm has been created from a typed schema as is the default case when calling GetInstance(RealmConfigurationBase) the returned object will be an instance of a user-defined class.

Exceptions

Type	Condition
RealmInvalidTransactionException	If you invoke this when there is no write Transaction active on the Realm.
ArgumentNullException	If you pass `null` for an object with string primary key.
ArgumentException	If you pass `primaryKey` with type that is different from the type, defined in the schema.

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DeleteRealm(RealmConfigurationBase)

Deletes all the files associated with a realm.

Declaration

public static void DeleteRealm(RealmConfigurationBase configuration)

Parameters

Type	Name	Description
RealmConfigurationBase	configuration	A RealmConfigurationBase which supplies the realm path.

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Dispose()

Disposes the current instance and closes the native Realm if this is the last remaining instance holding a reference to it.

Declaration

public void Dispose()

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Find(String, Nullable<Int64>)

Fast lookup of an object for dynamic use, from a class which has a PrimaryKey property.

Declaration

public RealmObject Find(string className, long? primaryKey)

Parameters

Type	Name	Description
String	className	Name of class in dynamic situation.
Nullable<Int64>	primaryKey	Primary key to be matched exactly, same as an == search. An argument of type `long?` works for all integer properties, supported as PrimaryKey.

Returns

Type	Description
RealmObject	`null` or an object matching the primary key.

Exceptions

Type	Condition
RealmClassLacksPrimaryKeyException	If the RealmObject class T lacks PrimaryKeyAttribute.

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Find(String, String)

Fast lookup of an object for dynamic use, from a class which has a PrimaryKey property.

Declaration

public RealmObject Find(string className, string primaryKey)

Parameters

Type	Name	Description
String	className	Name of class in dynamic situation.
String	primaryKey	Primary key to be matched exactly, same as an == search.

Returns

Type	Description
RealmObject	`null` or an object matching the primary key.

Exceptions

Type	Condition
RealmClassLacksPrimaryKeyException	If the RealmObject class T lacks PrimaryKeyAttribute.

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Find<T>(Nullable<Int64>)

Fast lookup of an object from a class which has a PrimaryKey property.

Declaration

public T Find<T>(long? primaryKey)

    where T : RealmObject

Parameters

Type	Name	Description
Nullable<Int64>	primaryKey	Primary key to be matched exactly, same as an == search. An argument of type `long?` works for all integer properties, supported as PrimaryKey.

Returns

Type	Description
T	`null` or an object matching the primary key.

Type Parameters

Name	Description
T	The Type T must be a RealmObject.

Exceptions

Type	Condition
RealmClassLacksPrimaryKeyException	If the RealmObject class T lacks PrimaryKeyAttribute.

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Find<T>(String)

Fast lookup of an object from a class which has a PrimaryKey property.

Declaration

public T Find<T>(string primaryKey)

    where T : RealmObject

Parameters

Type	Name	Description
String	primaryKey	Primary key to be matched exactly, same as an == search.

Returns

Type	Description
T	`null` or an object matching the primary key.

Type Parameters

Name	Description
T	The Type T must be a RealmObject.

Exceptions

Type	Condition
RealmClassLacksPrimaryKeyException	If the RealmObject class T lacks PrimaryKeyAttribute.

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Freeze()

Returns a frozen (immutable) snapshot of this Realm.

A frozen Realm is an immutable snapshot view of a particular version of a Realm's data. Unlike normal Realm instances, it does not live-update to reflect writes made to the Realm, and can be accessed from any thread. Writing to a frozen Realm is not allowed, and attempting to begin a write transaction will throw an exception.

All objects and collections read from a frozen Realm will also be frozen.

Note: Keeping a large number of frozen Realms with different versions alive can have a negative impact on the filesize of the underlying database. In order to avoid such a situation it is possible to set MaxNumberOfActiveVersions.

Declaration

public Realm Freeze()

Returns

Type	Description
Realm	A frozen Realm instance.

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GetInstance(RealmConfigurationBase)

Factory for obtaining a Realm instance for this thread.

Declaration

public static Realm GetInstance(RealmConfigurationBase config = null)

Parameters

Type	Name	Description
RealmConfigurationBase	config	Optional configuration.

Returns

Type	Description
Realm	A Realm instance.

Exceptions

Type	Condition
RealmFileAccessErrorException	Thrown if the file system returns an error preventing file creation.

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GetInstance(String)

Factory for obtaining a Realm instance for this thread.

Declaration

public static Realm GetInstance(string databasePath)

Parameters

Type	Name	Description
String	databasePath	Path to the realm, must be a valid full path for the current platform, relative subdirectory, or just filename.

Returns

Type	Description
Realm	A Realm instance.

Remarks

If you specify a relative path, sandboxing by the OS may cause failure if you specify anything other than a subdirectory.

Exceptions

Type	Condition
RealmFileAccessErrorException	Thrown if the file system returns an error preventing file creation.

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GetInstanceAsync(RealmConfigurationBase, CancellationToken)

Factory for asynchronously obtaining a Realm instance.

Declaration

public static Task<Realm> GetInstanceAsync(RealmConfigurationBase config = null, CancellationToken cancellationToken = default(CancellationToken))

Parameters

Type	Name	Description
RealmConfigurationBase	config	A configuration object that describes the realm.
CancellationToken	cancellationToken	An optional cancellation token that can be used to cancel the work.

Returns

Type	Description
Task<Realm>	A Task<TResult> that is completed once the remote realm is fully synchronized or immediately if it's a local realm.

Remarks

If the configuration points to a remote realm belonging to a Realm Object Server the realm will be downloaded and fully synchronized with the server prior to the completion of the returned Task object. Otherwise this method behaves identically to GetInstance(RealmConfigurationBase) and immediately returns a completed Task.

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IsSameInstance(Realm)

Determines whether this instance is the same core instance as the passed in argument.

Declaration

public bool IsSameInstance(Realm other)

Parameters

Type	Name	Description
Realm	other	The Realm to compare with the current Realm.

Returns

Type	Description
Boolean	`true` if this instance is the same core instance; otherwise, `false`.

Remarks

You can, and should, have multiple instances open on different threads which have the same path and open the same Realm.

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Refresh()

Update the Realm instance and outstanding objects to point to the most recent persisted version.

Declaration

public bool Refresh()

Returns

Type	Description
Boolean	Whether the Realm had any updates. Note that this may return true even if no data has actually changed.

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RefreshAsync()

Asynchronously wait for the Realm instance and outstanding objects to get updated to point to the most recent persisted version.

Declaration

public Task<bool> RefreshAsync()

Returns

Type	Description
Task<Boolean>	Whether the Realm had any updates. Note that this may return true even if no data has actually changed.

Remarks

On worker threads (where the SynchronizationContext) is null, this will call the blocking Refresh() method instead. On the main thread (or other threads that have SynchronizationContext), this will wait until the instance automatically updates to resolve the task. Note that you must keep a reference to the Realm until the returned task is resolved.

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Remove(RealmObject)

Removes a persistent object from this Realm, effectively deleting it.

Declaration

public void Remove(RealmObject obj)

Parameters

Type	Name	Description
RealmObject	obj	Must be an object persisted in this Realm.

Exceptions

Type	Condition
RealmInvalidTransactionException	If you invoke this when there is no write Transaction active on the Realm.
ArgumentNullException	If `obj` is `null`.
ArgumentException	If you pass a standalone object.

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RemoveAll()

Remove all objects of all types managed by this Realm.

Declaration

public void RemoveAll()

Exceptions

Type	Condition
RealmInvalidTransactionException	If you invoke this when there is no write Transaction active on the Realm.

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RemoveAll(String)

Remove all objects of a type from the Realm.

Declaration

public void RemoveAll(string className)

Parameters

Type	Name	Description
String	className	Type of the objects to remove as defined in the schema.

Exceptions

Type	Condition
RealmInvalidTransactionException	If you invoke this when there is no write Transaction active on the Realm.
ArgumentException	If you pass `className` that does not belong to this Realm's schema.

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RemoveAll<T>()

Remove all objects of a type from the Realm.

Declaration

public void RemoveAll<T>()

    where T : RealmObject

Type Parameters

Name	Description
T	Type of the objects to remove.

Exceptions

Type	Condition
RealmInvalidTransactionException	If you invoke this when there is no write Transaction active on the Realm.
ArgumentException	If the type T is not part of the limited set of classes in this Realm's Schema.

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RemoveRange<T>(IQueryable<T>)

Remove objects matching a query from the Realm.

Declaration

public void RemoveRange<T>(IQueryable<T> range)

    where T : RealmObject

Parameters

Type	Name	Description
IQueryable<T>	range	The query to match for.

Type Parameters

Name	Description
T	Type of the objects to remove.

Exceptions

Type	Condition
RealmInvalidTransactionException	If you invoke this when there is no write Transaction active on the Realm.
ArgumentException	If `range` is not the result of All<T>() or subsequent LINQ filtering.
ArgumentNullException	If `range` is `null`.

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ResolveReference<T>(ThreadSafeReference.List<T>)

Returns the same collection as the one referenced when the ThreadSafeReference.List<T> was first created, but resolved for the current Realm for this thread.

Declaration

public IList<T> ResolveReference<T>(ThreadSafeReference.List<T> reference)

Parameters

Type	Name	Description
ThreadSafeReference.List<T>	reference	The thread-safe reference to the thread-confined IList<T> to resolve in this Realm.

Returns

Type	Description
IList<T>	A thread-confined instance of the original IList<T> resolved for the current thread or `null` if the list's parent object has been deleted after the reference was created.

Type Parameters

Name	Description
T	The type of the objects, contained in the collection.

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ResolveReference<T>(ThreadSafeReference.Object<T>)

Returns the same object as the one referenced when the ThreadSafeReference.Object<T> was first created, but resolved for the current Realm for this thread.

Declaration

public T ResolveReference<T>(ThreadSafeReference.Object<T> reference)

    where T : RealmObject

Parameters

Type	Name	Description
ThreadSafeReference.Object<T>	reference	The thread-safe reference to the thread-confined RealmObject to resolve in this Realm.

Returns

Type	Description
T	A thread-confined instance of the original RealmObject resolved for the current thread or `null` if the object has been deleted after the reference was created.

Type Parameters

Name	Description
T	The type of the object, contained in the reference.

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ResolveReference<T>(ThreadSafeReference.Query<T>)

Returns the same query as the one referenced when the ThreadSafeReference.Query<T> was first created, but resolved for the current Realm for this thread.

Declaration

public IQueryable<T> ResolveReference<T>(ThreadSafeReference.Query<T> reference)

    where T : RealmObject

Parameters

Type	Name	Description
ThreadSafeReference.Query<T>	reference	The thread-safe reference to the thread-confined IQueryable<T> to resolve in this Realm.

Returns

Type	Description
IQueryable<T>	A thread-confined instance of the original IQueryable<T> resolved for the current thread.

Type Parameters

Name	Description
T	The type of the object, contained in the query.

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Write(Action)

Execute an action inside a temporary Transaction. If no exception is thrown, the Transaction will be committed.

Declaration

public void Write(Action action)

Parameters

Type	Name	Description
Action	action	Action to perform inside a Transaction, creating, updating or removing objects.

Remarks

Creates its own temporary Transaction and commits it after running the lambda passed to action. Be careful of wrapping multiple single property updates in multiple Write(Action) calls. It is more efficient to update several properties or even create multiple objects in a single Write(Action), unless you need to guarantee finer-grained updates.

Examples

realm.Write(() =>
{
    realm.Add(new Dog
    {
        Name = "Eddie",
        Age = 5
    });
});

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WriteAsync(Action<Realm>)

Execute an action inside a temporary Transaction on a worker thread, if called from UI thread. If no exception is thrown, the Transaction will be committed.

Declaration

public Task WriteAsync(Action<Realm> action)

Parameters

Type	Name	Description
Action<Realm>	action	Action to perform inside a Transaction, creating, updating, or removing objects.

Returns

Type	Description
Task	An awaitable Task.

Remarks

Opens a new instance of this Realm on a worker thread and executes action inside a write Transaction. Realms and RealmObjects are thread-affine, so capturing any such objects in the action delegate will lead to errors if they're used on the worker thread. Note that it checks the SynchronizationContext to determine if Current is null, as a test to see if you are on the UI thread and will otherwise just call Write without starting a new thread. So if you know you are invoking from a worker thread, just call Write instead.

Examples

await realm.WriteAsync(tempRealm =>
{
    var pongo = tempRealm.All<Dog>().Single(d => d.Name == "Pongo");
    var missis = tempRealm.All<Dog>().Single(d => d.Name == "Missis");
    for (var i = 0; i < 15; i++)
    {
        tempRealm.Add(new Dog
        {
            Breed = "Dalmatian",
            Mum = missis,
            Dad = pongo
        });
    }
});

Note that inside the action, we use tempRealm.

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WriteCopy(RealmConfigurationBase)

Writes a compacted copy of the Realm to the path in the specified config. If the configuration object has non-null EncryptionKey, the copy will be encrypted with that key.

Declaration

public void WriteCopy(RealmConfigurationBase config)

Parameters

Type	Name	Description
RealmConfigurationBase	config	Configuration, specifying the path and optionally the encryption key for the copy.

Remarks

The destination file cannot already exist.

If this is called from within a transaction it writes the current data, and not the data as it was when the last transaction was committed.

Events

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Error

Triggered when a Realm-level exception has occurred.

Declaration

public event EventHandler<ErrorEventArgs> Error

Event Type

Type	Description
EventHandler<ErrorEventArgs>

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RealmChanged

Triggered when a Realm has changed (i.e. a Transaction was committed).

Declaration

public event Realm.RealmChangedEventHandler RealmChanged

Event Type

Type	Description
Realm.RealmChangedEventHandler

Implements

System.IDisposable

Extension Methods

RealmSyncExtensions.GetSession(Realm)

PermissionExtensions.GetPrivileges(Realm)

PermissionExtensions.GetPrivileges<T>(Realm)

PermissionExtensions.GetPrivileges(Realm, String)

PermissionExtensions.GetPrivileges(Realm, RealmObject)

Subscription.GetAllSubscriptions(Realm)

Subscription.UnsubscribeAsync(Realm, String)