firebase:: database:: Query
#include <query.h>
The Query class is used for reading data.
Summary
Listeners can be attached, which will be triggered when the data changes.
Inheritance
Direct Known Subclasses:firebase::database::DatabaseReference
Constructors and Destructors |
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Query()
Default constructor.
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Query(const Query & query)
Copy constructor.
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Query(Query && query)
Move constructor.
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~Query()
Required virtual destructor.
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Public functions |
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AddChildListener(ChildListener *listener)
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void
Adds a listener that will be called any time a child is added, removed, modified, or reordered.
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AddValueListener(ValueListener *listener)
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void
Adds a listener that will be called immediately and then again any time the data changes.
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EndAt(Variant order_value)
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Get a Query constrained to nodes with the given sort value or lower.
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EndAt(Variant order_value, const char *child_key)
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Get a Query constrained to nodes with the given sort value or lower, and the given key or lower.
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EqualTo(Variant order_value)
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Get a Query constrained to nodes with the exact given sort value.
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EqualTo(Variant order_value, const char *child_key)
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Get a Query constrained to nodes with the exact given sort value, and the exact given key.
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GetReference() const
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Gets a DatabaseReference corresponding to the given location.
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GetValue()
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Gets the value of the query for the given location a single time.
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GetValueLastResult()
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Gets the result of the most recent call to GetValue().
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LimitToFirst(size_t limit)
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Gets a Query limited to only the first results.
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LimitToLast(size_t limit)
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Gets a Query limited to only the last results.
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OrderByChild(const char *path)
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Gets a query in which child nodes are ordered by the values of the specified path.
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OrderByChild(const std::string & path)
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Gets a query in which child nodes are ordered by the values of the specified path.
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OrderByKey()
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Gets a query in which child nodes are ordered by their keys.
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OrderByPriority()
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Gets a query in which child nodes are ordered by their priority.
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OrderByValue()
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Create a query in which nodes are ordered by their value.
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RemoveAllChildListeners()
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void
Removes all child listeners that were added by AddChildListener().
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RemoveAllValueListeners()
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void
Removes all value listeners that were added with AddValueListener().
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RemoveChildListener(ChildListener *listener)
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void
Removes a listener that was previously added with AddChildListener().
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RemoveValueListener(ValueListener *listener)
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void
Removes a listener that was previously added with AddValueListener().
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SetKeepSynchronized(bool keep_sync)
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void
Sets whether this location's data should be kept in sync even if there are no active Listeners.
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StartAt(Variant order_value)
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Get a Query constrained to nodes with the given sort value or higher.
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StartAt(Variant order_value, const char *child_key)
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Get a Query constrained to nodes with the given sort value or higher, and the given key or higher.
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is_valid() const
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virtual bool
Returns true if this query is valid, false if it is not valid.
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operator=(const Query & query)
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Query &
Copy assignment operator.
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operator=(Query && query)
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Query &
Move assignment operator.
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Public functions
AddChildListener
void AddChildListener( ChildListener *listener )
Adds a listener that will be called any time a child is added, removed, modified, or reordered.
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Parameters |
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AddValueListener
void AddValueListener( ValueListener *listener )
Adds a listener that will be called immediately and then again any time the data changes.
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Parameters |
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EndAt
Query EndAt( Variant order_value )
Get a Query constrained to nodes with the given sort value or lower.
This method is used to generate a reference to a limited view of the data at this location. The Query returned will only refer to child nodes with a value less than or equal to the given value, using the given OrderBy directive (or priority as default).
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Parameters |
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Returns |
A Query in this same location, filtering out child nodes that have a higher sort value or key than the sort value or key specified.
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EndAt
Query EndAt( Variant order_value, const char *child_key )
Get a Query constrained to nodes with the given sort value or lower, and the given key or lower.
This method is used to generate a reference to a limited view of the data at this location. The Query returned will only refer to child nodes with a value less than or equal to the given value, using the given OrderBy directive (or priority as default), and additionally only child nodes with a key less than or equal to the given key.
Known issue This currently does not work properly on all platforms. Please use EndAt(Variant order_value) instead.
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Parameters |
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Returns |
A Query in this same location, filtering out child nodes that have a higher sort value than the sort value specified, or a higher key than the key specified.
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EqualTo
Query EqualTo( Variant order_value )
Get a Query constrained to nodes with the exact given sort value.
This method is used to create a query constrained to only return child nodes with the given value, using the given OrderBy directive (or priority as default).
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Parameters |
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Returns |
A Query in this same location, filtering out child nodes that have a different sort value than the sort value specified.
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EqualTo
Query EqualTo( Variant order_value, const char *child_key )
Get a Query constrained to nodes with the exact given sort value, and the exact given key.
This method is used to create a query constrained to only return the child node with the given value, using the given OrderBy directive (or priority as default), and the given key. Note