Conditional update¶
Atomically sets the value to the given updated value if the current value == the expected value.
Method:¶
PUT
Endpoint URL¶
https://xxxx.backendless.app/api/counters/<counterName>/get/compareandset?
expected=<expected>&updatedvalue=<updated>
where:
| Argument | Description |
|---|---|
<counterName> |
Name of the counter to update. |
<expected> |
The expected value of the counter. If the current value equals the expected value, the counter is set to the "updated" value. |
<updated> |
The new value to assign to the counter if the current value equals the expected value. |
Request headers¶
user-token: optional value obtained as a result of the login operation.
where:
| Argument | Description |
|---|---|
user-token |
Optional header. Contains a value returned by Backendless in a preceding user Login API call. The operation will be executed with the security policy associated currently logged in user. This means all permissions associated with the user and the roles assigned to the user will be enforced by Backendless. |
Request body¶
N/A
Response body¶
Boolean value - true if the counter has been updated, false otherwise
Example¶
Make sure to replace xxxx in the domain name in the sample request below to the one assigned to your application.
curl -X PUT \
https://xxxx.backendless.app/api/counters/mycounter/get/compareandset?expected=1000&updatedvalue=2000
Codeless Reference¶
where:
| Argument | Description |
|---|---|
counter name |
Name of the counter whose value must be set. |
expected value |
This property sets the following condition: If the expected value equals to the current value of the counter, then the operation sets a new number for the counter. Otherwise, the operation does not set the new value for the counter. |
new value |
Specify the new number for the counter. |
return current value |
When this box is checked, the operation returns the current value of the counter. |
Returns the current value of the counter.
Consider the following counter:
The example below checks if the expected value of the "CarsParkingLot" counter equals to 20, and if it does equal to 20, then the operation sets a new value to 35.
The result of this operation will look as shown below after the Codeless logic runs:
