Feature Flag Determination


Feature flags are only available for SDK version 2.0.0 or higher.

When using feature flags, please apply SDK version 2.0.0 or higher when adding dependencies.

A feature flag has an on and off state. You will set different features according to each state.

Once a feature flag is applied, a specific user from your traffic should be able to either receive an off or on status. This on/off status determination can be done through the Hackle SDK.


You can pass a feature key to the is_feature_on() method to receive status results for the user. After receiving the status, we can then implement the logic according to each status.

In the example code below, we are passing feature key 42.

In the example code below, we are passing feature key 42, and the user identifier of the user who will receive the status is "ae03e1adf" .

# Determines the status of the feature flag to assign the user in a feature flag with a feature key of 42.
# For undetermined cases, users are assigned to false (off status). 
user = Hackle.user('ae03e1adf')
feature_on = hackle_client.is_feature_on(feature_key=42, user=user)

# Logic by state
if feature_on == True:
    # Logic for on status
elif feature_on == False:
    # Logic for off status


The feature_flag_detail() method works the same as the is_feature_on() method and additionally provides a reason for determining the status of a particular user. This can be useful when you want to check whether the manual allocation is working well or when you think that the traffic allocation you have set is not being reflected in your results.

You must pass a feature key as a parameter. For the example code below, we are passing feature key 42.

decison = hackle_client.feature_flag_detail(feature_key=42, user=user)

# Feature flag on/off results
feature_on = decison.is_on

# Reason for status determination
reason = decision.reason

The reason for the status determination will be in the form of SDK_NOT_READY. Please refer to the table below for the full list of all the different types of reasons.



Feature Status


The SDK is not ready to use.
(e.g. Initialization with the wrong SDK key)

Default status(off)


No feature flags were found for the feature key you passed.
The feature key may be incorrect or the corresponding feature flag may be in an archived state.

Default status(off)


The user has been determined to have a specific feature flag status by manual assignment.

Manual assignment


User status has been determined.

Status determined


The input value is not valid.
(e.g. A letter type was inputting in a parameter that requires a numeric type)

Default status(off)


An unknown error has occurred.

Default status(off)

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