firebase::
#include <data_snapshot.h>
A DataSnapshot instance contains data from a Firebase Database location.
Summary
Any time you read Database data, you receive the data as a DataSnapshot. These are efficiently-generated and cannot be changed. To modify data, use DatabaseReference::SetValue() or DatabaseReference::RunTransaction().
Constructors and Destructors | |
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DataSnapshot() Default constructor. | |
DataSnapshot(const DataSnapshot & snapshot) Copy constructor. | |
DataSnapshot(DataSnapshot && snapshot) Move constructor. | |
~DataSnapshot() Destructor. |
Public functions | |
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Child(const char *path) const | Get a DataSnapshot for the location at the specified relative path. |
Child(const std::string & path) const | Get a DataSnapshot for the location at the specified relative path. |
GetReference() const | Obtain a DatabaseReference to the source location for this snapshot. |
HasChild(const char *path) const | bool Does this DataSnapshot have data at a particular location? |
HasChild(const std::string & path) const | bool Does this DataSnapshot have data at a particular location? |
children() const | std::vector< DataSnapshot > Get all the immediate children of this location. |
children_count() const | size_t Get the number of children of this location. |
exists() const | bool Returns true if the data is non-empty. |
has_children() const | bool Does this DataSnapshot have any children at all? |
is_valid() const | bool Returns 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::string Get the key name of the source location of this snapshot. |
operator=(const DataSnapshot & 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
DataSnapshot Child( const char *path ) const
Get a DataSnapshot for the location at the specified relative path.
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| Returns | A DataSnapshot corresponding to specified child location. |
Child
DataSnapshot Child( const std::string & path ) const
Get a DataSnapshot for the location at the specified relative path.
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| Returns | A DataSnapshot corresponding to specified child location. |
DataSnapshot
DataSnapshot()
Default constructor.
This DataSnapshot contains nothing and is considered invalid (i.e. is_valid() == false). Use this to construct an empty DataSnapshot that you will later populate with data from a database callback.
DataSnapshot
DataSnapshot( const DataSnapshot & 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
DatabaseReference GetReference() const
Obtain a DatabaseReference to the source location for this snapshot.
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| Returns | A DatabaseReference corresponding to same location as this snapshot. |
HasChild
bool HasChild( const char *path ) const
Does this DataSnapshot 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
bool HasChild( const std::string & path ) const
Does this DataSnapshot 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_t children_count() const
Get the number of children of this location.
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| Returns | The number of immediate children of this snapshot. |
exists
bool exists() const
Returns true if the data is non-empty.
has_children
bool has_children() const
Does this DataSnapshot have any children at all?
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| Returns | True if the snapshot has any children, false otherwise. |
is_valid
bool is_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
const char * key() 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. |
key_string
std::string key_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=( const DataSnapshot & snapshot )
Copy assignment operator.
DataSnapshots are immutable, so they can be efficiently copied.
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| Returns | Reference to the destination DataSnapshot. |
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 destination DataSnapshot. |
priority
Variant priority() 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
Variant value() 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.