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/*
* Copyright 2017 Google
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#import <Foundation/Foundation.h>
NS_ASSUME_NONNULL_BEGIN
@class FIRDatabaseReference;
/**
* A FIRDataSnapshot contains data from a Firebase Database location. Any time you read
* Firebase data, you receive the data as a FIRDataSnapshot.
*
* FIRDataSnapshots are passed to the blocks you attach with observeEventType:withBlock: or observeSingleEvent:withBlock:.
* They are efficiently-generated immutable copies of the data at a Firebase Database location.
* They can't be modified and will never change. To modify data at a location,
* use a FIRDatabaseReference (e.g. with setValue:).
*/
NS_SWIFT_NAME(DataSnapshot)
@interface FIRDataSnapshot : NSObject
#pragma mark - Navigating and inspecting a snapshot
/**
* Gets a FIRDataSnapshot for the location at the specified relative path.
* The relative path can either be a simple child key (e.g. 'fred')
* or a deeper slash-separated path (e.g. 'fred/name/first'). If the child
* location has no data, an empty FIRDataSnapshot is returned.
*
* @param childPathString A relative path to the location of child data.
* @return The FIRDataSnapshot for the child location.
*/
- (FIRDataSnapshot *)childSnapshotForPath:(NSString *)childPathString;
/**
* Return YES if the specified child exists.
*
* @param childPathString A relative path to the location of a potential child.
* @return YES if data exists at the specified childPathString, else NO.
*/
- (BOOL) hasChild:(NSString *)childPathString;
/**
* Return YES if the DataSnapshot has any children.
*
* @return YES if this snapshot has any children, else NO.
*/
- (BOOL) hasChildren;
/**
* Return YES if the DataSnapshot contains a non-null value.
*
* @return YES if this snapshot contains a non-null value, else NO.
*/
- (BOOL) exists;
#pragma mark - Data export
/**
* Returns the raw value at this location, coupled with any metadata, such as priority.
*
* Priorities, where they exist, are accessible under the ".priority" key in instances of NSDictionary.
* For leaf locations with priorities, the value will be under the ".value" key.
*/
- (id __nullable) valueInExportFormat;
#pragma mark - Properties
/**
* Returns the contents of this data snapshot as native types.
*
* Data types returned:
* + NSDictionary
* + NSArray
* + NSNumber (also includes booleans)
* + NSString
*
* @return The data as a native object.
*/
@property (strong, readonly, nonatomic, nullable) id value;
/**
* Gets the number of children for this DataSnapshot.
*
* @return An integer indicating the number of children.
*/
@property (readonly, nonatomic) NSUInteger childrenCount;
/**
* Gets a FIRDatabaseReference for the location that this data came from.
*
* @return A FIRDatabaseReference instance for the location of this data.
*/
@property (nonatomic, readonly, strong) FIRDatabaseReference * ref;
/**
* The key of the location that generated this FIRDataSnapshot.
*
* @return An NSString containing the key for the location of this FIRDataSnapshot.
*/
@property (strong, readonly, nonatomic) NSString* key;
/**
* An iterator for snapshots of the child nodes in this snapshot.
* You can use the native for..in syntax:
*
* for (FIRDataSnapshot* child in snapshot.children) {
* ...
* }
*
* @return An NSEnumerator of the children.
*/
@property (strong, readonly, nonatomic) NSEnumerator<FIRDataSnapshot *>* children;
/**
* The priority of the data in this FIRDataSnapshot.
*
* @return The priority as a string, or nil if no priority was set.
*/
@property (strong, readonly, nonatomic, nullable) id priority;
@end
NS_ASSUME_NONNULL_END
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