firebase::
#include <data_snapshot.h>
ADataSnapshot instance contains data from a FirebaseDatabase location.
Summary
Any time you readDatabase data, you receive the data as aDataSnapshot. These are efficiently-generated and cannot be changed. To modify data, useDatabaseReference::SetValue() orDatabaseReference::RunTransaction().
Constructors and Destructors | |
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DataSnapshot()Default constructor. | |
DataSnapshot(constDataSnapshot & snapshot)Copy constructor. | |
DataSnapshot(DataSnapshot && snapshot)Move constructor. | |
~DataSnapshot()Destructor. |
Public functions | |
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Child(const char *path) const | Get aDataSnapshot for the location at the specified relative path. |
Child(const std::string & path) const | Get aDataSnapshot for the location at the specified relative path. |
GetReference() const | Obtain aDatabaseReference to the source location for this snapshot. |
HasChild(const char *path) const | boolDoes thisDataSnapshot have data at a particular location? |
HasChild(const std::string & path) const | boolDoes thisDataSnapshot have data at a particular location? |
children() const | std::vector<DataSnapshot >Get all the immediate children of this location. |
children_count() const | size_tGet the number of children of this location. |
exists() const | boolReturns true if the data is non-empty. |
has_children() const | boolDoes thisDataSnapshot have any children at all? |
is_valid() const | boolReturns true if this snapshot is valid, false if it is not valid. |
key() const | const char *Get the key name of the source location of this snapshot. |
key_string() const | std::stringGet the key name of the source location of this snapshot. |
operator=(constDataSnapshot & snapshot) | Copy assignment operator. |
operator=(DataSnapshot && snapshot) | Move assignment operator. |
priority() const | Get the priority of the data contained in this snapshot. |
value() const | Get the value of the data contained in this snapshot. |
Public functions
Child
DataSnapshotChild(constchar*path)const
Get aDataSnapshot for the location at the specified relative path.
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| Returns | ADataSnapshot corresponding to specified child location. |
Child
DataSnapshotChild(conststd::string&path)const
Get aDataSnapshot for the location at the specified relative path.
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| Returns | ADataSnapshot corresponding to specified child location. |
DataSnapshot
DataSnapshot()
Default constructor.
ThisDataSnapshot contains nothing and is considered invalid (i.e.is_valid() == false). Use this to construct an emptyDataSnapshot that you will later populate with data from a database callback.
DataSnapshot
DataSnapshot(constDataSnapshot&snapshot)
Copy constructor.
DataSnapshots are immutable, so they can be efficiently copied.
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DataSnapshot
DataSnapshot(DataSnapshot&&snapshot)
Move constructor.
DataSnapshots are immutable, so they can be efficiently moved.
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GetReference
DatabaseReferenceGetReference()const
Obtain aDatabaseReference to the source location for this snapshot.
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| Returns | ADatabaseReference corresponding to same location as this snapshot. |
HasChild
boolHasChild(constchar*path)const
Does thisDataSnapshot have data at a particular location?
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| Returns | True if the snapshot has data at the specified location, false if not. |
HasChild
boolHasChild(conststd::string&path)const
Does thisDataSnapshot have data at a particular location?
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| Returns | True if the snapshot has data at the specified location, false if not. |
children
std::vector<DataSnapshot>children()const
Get all the immediate children of this location.
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| Returns | The immediate children of this snapshot. |
children_count
size_tchildren_count()const
Get the number of children of this location.
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| Returns | The number of immediate children of this snapshot. |
exists
boolexists()const
Returns true if the data is non-empty.
has_children
boolhas_children()const
Does thisDataSnapshot have any children at all?
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| Returns | True if the snapshot has any children, false otherwise. |
is_valid
boolis_valid()const
Returns true if this snapshot is valid, false if it is not valid.
An invalid snapshot could be returned by a transaction where an error has occurred.
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| Returns | true if this snapshot is valid, false if this snapshot is invalid. |
key
constchar*key()const
Get the key name of the source location of this snapshot.
Note: The returned pointer is only guaranteed to be valid while theDataSnapshot is still in memory.
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| Returns | Key name of the source location of this snapshot. |
key_string
std::stringkey_string()const
Get the key name of the source location of this snapshot.
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| Returns | Key name of the source location of this snapshot. |
operator=
DataSnapshot&operator=(constDataSnapshot&snapshot)
Copy assignment operator.
DataSnapshots are immutable, so they can be efficiently copied.
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| Returns | Reference to the destinationDataSnapshot. |
operator=
DataSnapshot&operator=(DataSnapshot&&snapshot)
Move assignment operator.
DataSnapshots are immutable, so they can be efficiently moved.
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| Returns | Reference to this destinationDataSnapshot. |
priority
Variantpriority()const
Get the priority of the data contained in this snapshot.
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| Returns | The value of this location's Priority relative to its siblings. |
value
Variantvalue()const
Get the value of the data contained in this snapshot.
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| Returns | The value of the data contained in this location. |
~DataSnapshot
~DataSnapshot()
Destructor.
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Last updated 2024-01-23 UTC.