MutableData

public class MutableData

Instances of this class encapsulate the data and priority at a location. It is used in transactions, and it is intended to be inspected and then updated to the desired data at that location. Note that changes made to a child MutableData instance will be visible to the parent and vice versa.

Summary

Public methods
`@NonNull MutableData`	`child(@NonNull String path)` Used to obtain a MutableData instance that encapsulates the data and priority at the given relative path.
`boolean`	`equals(Object o)`
`@NonNull Iterable<MutableData>`	`getChildren()` Used to iterate over the immediate children at this location
`long`	`getChildrenCount()`
`@Nullable String`	`getKey()`
`@Nullable Object`	`getPriority()` Gets the current priority at this location.
`@Nullable Object`	`getValue()` getValue() returns the data contained in this instance as native types.
`@Nullable T`	`<T> getValue(@NonNull GenericTypeIndicator<T> t)` Due to the way that Java implements generics, it takes an extra step to get back a properly-typed Collection.
`@Nullable T`	`<T> getValue(@NonNull Class<T> valueType)` This method is used to marshall the data contained in this instance into a class of your choosing.
`boolean`	`hasChild(@NonNull String path)`
`boolean`	`hasChildren()`
`void`	`setPriority(@Nullable Object priority)` Sets the priority at this location
`void`	`setValue(@Nullable Object value)` Set the data at this location to the given value.
`String`	`toString()`

Extension functions
`final T`	`<T extends Object> DatabaseKt.getValue(@NonNull MutableData receiver)` Returns the content of the MutableData converted to a POJO.
`final T`	`<T extends Object> DatabaseKt.getValue(@NonNull MutableData receiver)` This method is deprecated. Migrate to use the KTX API from the main module: https://firebase.google.com/docs/android/kotlin-migration.

Public methods

child

public @NonNull MutableData child(@NonNull String path)

Used to obtain a MutableData instance that encapsulates the data and priority at the given relative path.

Parameters
`@NonNull String path`	A relative path

Returns
`@NonNull MutableData`	An instance encapsulating the data and priority at the given path

equals

public boolean equals(Object o)

getChildren

public @NonNull Iterable<MutableData> getChildren()

Used to iterate over the immediate children at this location

    for (MutableData child : parent.getChildren()) {
            ...
    }

Returns
`@NonNull Iterable<MutableData>`	The immediate children at this location

getChildrenCount

public long getChildrenCount()

Returns
`long`	The number of immediate children at this location

getKey

public @Nullable String getKey()

Returns
`@Nullable String`	The key name of this location, or null if it is the top-most location

getPriority

public @Nullable Object getPriority()

Gets the current priority at this location. The possible return types are:

Double
String

Note that null is allowed

Returns
`@Nullable Object`	The priority at this location as a native type or null if no priority was set

getValue

public @Nullable Object getValue()

getValue() returns the data contained in this instance as native types. The possible types returned are:

Boolean
Long
Double
String
Map<String, Object>
List<Object>

This list is recursive; the possible types for java.lang.Object in the above list is given by the same list. These types correspond to the types available in JSON.

Returns
`@Nullable Object`	The data contained in this instance as native types, or null if there is no data at this location.

getValue

public @Nullable T <T> getValue(@NonNull GenericTypeIndicator<T> t)

Due to the way that Java implements generics, it takes an extra step to get back a properly-typed Collection. So, in the case where you want a java.util.List of Message instances, you will need to do something like the following:

    GenericTypeIndicator<List<Message>> t =
        new GenericTypeIndicator<List<Message>>() {};
    List<Message> messages = mutableData.getValue(t);

It is important to use a subclass of GenericTypeIndicator. See GenericTypeIndicator for more details

Parameters
`<T>`	The type to return. Implicitly defined from the `GenericTypeIndicator` passed in
`@NonNull GenericTypeIndicator<T> t`	A subclass of `GenericTypeIndicator` indicating the type of generic collection to be returned.

Returns
`@Nullable T`	A properly typed collection, populated with the data from this instance, or null if there is no data at this location.

getValue

public @Nullable T <T> getValue(@NonNull Class<T> valueType)

This method is used to marshall the data contained in this instance into a class of your choosing. The class must fit 2 simple constraints:

The class must have a default constructor that takes no arguments
The class must define public getters for the properties to be assigned. Properties without a public getter will be set to their default value when an instance is deserialized

An example class might look like:

    class Message {
        private String author;
        private String text;

        private Message() {}

        public Message(String author, String text) {
            this.author = author;
            this.text = text;
        }

        public String getAuthor() {
            return author;
        }

        public String getText() {
            return text;
        }
    }


    // Later
    Message m = mutableData.getValue(Message.class);

Parameters
`<T>`	The type to return. Implicitly defined from the class passed in
`@NonNull Class<T> valueType`	The class into which this data in this instance should be marshalled

Returns
`@Nullable T`	An instance of the class passed in, populated with the data from this instance, or null if there is no data at this location.

hasChild

public boolean hasChild(@NonNull String path)

Parameters
`@NonNull String path`	A relative path

Returns
`boolean`	True if data exists at the given path, otherwise false

hasChildren

public boolean hasChildren()

Returns
`boolean`	True if the data at this location has children, false otherwise

setPriority

public void setPriority(@Nullable Object priority)

Sets the priority at this location

Parameters
`@Nullable Object priority`	The desired priority or null to clear the existing priority

setValue

public void setValue(@Nullable Object value)

Set the data at this location to the given value. The native types accepted by this method for the value correspond to the JSON types:

Boolean
Long
Double
Map<String, Object>
List<Object>

In addition, you can set instances of your own class into this location, provided they satisfy the following constraints:

The class must have a default constructor that takes no arguments
The class must define public getters for the properties to be assigned. Properties without a public getter will be set to their default value when an instance is deserialized

Generic collections of objects that satisfy the above constraints are also permitted, i.e. Map<String, MyPOJO>, as well as null values.

Note that this overrides the priority, which must be set separately.

Parameters
`@Nullable Object value`	The value to set at this location or null to delete the existing data

Throws
`com.google.firebase.database.DatabaseException com.google.firebase.database.DatabaseException`

toString

public String toString()

Extension functions

DatabaseKt.getValue

public final T <T extends Object> DatabaseKt.getValue(@NonNull MutableData receiver)

Returns the content of the MutableData converted to a POJO.

Supports generics like List<> or Map<>. Use @JvmSuppressWildcards to force the compiler to use the type T, and not ? extends T.

DatabaseKt.getValue

public final T <T extends Object> DatabaseKt.getValue(@NonNull MutableData receiver)

Returns the content of the MutableData converted to a POJO.

Supports generics like List<> or Map<>. Use @JvmSuppressWildcards to force the compiler to use the type T, and not ? extends T.

Deprecation Notice: The Kotlin extensions (KTX) APIs have been added to their respective main modules, and the Kotlin extension (KTX) APIs in com.google.firebase.firebase-database-ktx are now deprecated. As early as April 2024, we'll no longer release KTX modules. For details, see the FAQ about this initiative.