MutableData

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

Extension functions
`inline T?`	`<T : Any?> MutableData.getValue()` Returns the content of the MutableData converted to a POJO.
`inline T?`	`<T : Any?> MutableData.getValue()` This function is deprecated. Migrate to use the KTX API from the main module: https://firebase.google.com/docs/android/kotlin-migration.

Public functions

child

fun child(path: String): MutableData

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

Parameters
`path: String`	A relative path

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

equals

fun equals(o: Any!): Boolean

getChildren

fun getChildren(): (Mutable)Iterable<MutableData!>

Used to iterate over the immediate children at this location

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

Returns
`(Mutable)Iterable<MutableData!>`	The immediate children at this location

getChildrenCount

fun getChildrenCount(): Long

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

getKey

fun getKey(): String?

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

getPriority

fun getPriority(): Any?

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

Double
String

Note that null is allowed

Returns
`Any?`	The priority at this location as a native type or null if no priority was set

getValue

fun getValue(): Any?

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
`Any?`	The data contained in this instance as native types, or null if there is no data at this location.

getValue

fun <T> getValue(t: 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
`t: GenericTypeIndicator<T!>`	A subclass of `GenericTypeIndicator` indicating the type of generic collection to be returned.

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

getValue

fun <T> getValue(valueType: Class<T!>): T?

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
`valueType: Class<T!>`	The class into which this data in this instance should be marshalled

Returns
`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

fun hasChild(path: String): Boolean

Parameters
`path: String`	A relative path

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

hasChildren

fun hasChildren(): Boolean

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

setPriority

fun setPriority(priority: Any?): Unit

Sets the priority at this location

Parameters
`priority: Any?`	The desired priority or null to clear the existing priority

setValue

fun setValue(value: Any?): Unit

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
`value: Any?`	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

fun toString(): String!

Extension functions

getValue

inline fun <T : Any?> MutableData.getValue(): T?

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.

getValue

inline fun <T : Any?> MutableData.getValue(): T?

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.