Check If Keys Exist

Description

This operation checks if specific keys exist in the specified store.

Method

Objective-CSwift

// Check One Key

[[[Backendless.shared hive:(NSString *)hiveName] storeType] existsWithKey:(NSString *)key responseHandler:^(BOOL)responseHandler errorHandler:^(Fault *)errorHandler];

// Check Multiple Keys

[[[Backendless.shared hive:(NSString *)hiveName] storeType] existsWithKeys:(NSArray<NSString *> *)keys responseHandler:^(NSInteger)responseHandler errorHandler:^(Fault *)errorHandler];

// Check One Key

Backendless.shared.hive(hiveName: String).storeType.exists(key: String, responseHandler: ((Bool) -> Void)!, errorHandler: ((Fault) -> Void)!)

// Check Multiple Keys

Backendless.shared.hive(hiveName: String).storeType.exists(keys: [String], responseHandler: ((Int) -> Void)!, errorHandler: ((Fault) -> Void)!)

where:

Argument	Description
hiveName	Name of a hive where the operation is performed. String value.
storeType	This placeholder must be substituted with one of the following stores types: keyValueStore, listStore, mapStore, setStore, sortedSetStore.
keys	Represents an array of keys to check if they exist in a store. Array of string values.
key	Identifies a single key to check if it exists in a store. String value.

Return Value

Number of found keys. Otherwise, 0 is returned if the specified keys do not exist.

Example

Check One Key

This example checks if the "fruits" key exists in the key-value store.

Objective-CSwift

[[[Backendless.shared hive:@"groceryStore"] keyValueStore] existsWithKey:@"fruits" responseHandler:^(BOOL response) {
    // handle response
} errorHandler:^(Fault *fault) {
    // handle error
}];

Backendless.shared.hive("groceryStore").keyValueStore.exists(key: "fruits", responseHandler: { response in
    // handle response
}, errorHandler: { fault in
    // handle error
})

where:

Argument	Description
"groceryStore"	Name of the hive where the operation is performed.
"fruits"	Key name to check for existence.

Check Multiple Keys

The example below checks if the "fruits" and "vegetables" keys exist in the key-value store.

Objective-CSwift

[[[Backendless.shared hive:@"groceryStore"] keyValueStore] existsWithKey:@"fruits" responseHandler:^(BOOL response) {
    // handle response
} errorHandler:^(Fault *fault) {
    // handle error
}];

Backendless.shared.hive("groceryStore").keyValueStore.exists(key: "fruits", responseHandler: { response in
    // handle response
}, errorHandler: { fault in
    // handle error
})

where:

Argument	Description
"groceryStore"	Name of the hive where the operation is performed.
["fruits","vegetables"]	An array of key names to check for existence.

Codeless Reference

where:

Argument	Description
hive name	Name of a hive where the operation is performed.
type	Storage type, can be one of the following: Key / Value, Sorted Set, Set, Map, List.
keys	An array of keys to check for existence.

Returns the number of found keys. Otherwise, 0 is returned if the specified keys do not exist.

Consider the following Key Value storage:

The example below checks if the "Japan" and "USA" keys exist in the the Key Value storage of the countries hive. The block returns a number of keys found in the store.

The output will look as shown below after the Codeless logic runs.

To check for a single key, use the following block. The blocks returns a boolean true or false value indicating whether the specific key exists in the store.

where:

Argument	Description
hive name	Name of a hive where the operation is performed.
type	Type of the storage used for this operation.
key name	Key name to check for existence.

The example below checks if the "Japan" key exists in the Key / Value store of the countries hive:

The output will look as shown below after the Codeless logic runs.