Segments allow you to group your users based on a set of rules, and then control Feature Flags and Remote Config for those groups. You can create a Segment and then override a Feature Flag state or Remote Config value for that segment of users.
Segments for Flags and Config are overridden at the Environment level, meaning that different Environments can define their own Segment overrides.
Segments are not sent back to client SDKs. They are used to override flag values within the dashboard, but they are never sent back to our SDKs from the API. Learn more about our architecture.
Example - Beta Users
Segment definitions can be defined at the Project or Flag level. Project level Segments are defined at the Project level and can be used with any number of Flags within that Project. Flag Specific Segments can only affect the Flag they are defined within.
You create a new Segment, call it
Beta Users, and define a single rule:
Once the Segment has been defined, you can then associate that Segment with a specific Feature Flag. To do this, open the Feature Flag that you want to connect the Segment to and navigate to the Segment Overrides tab. You then have the option of connecting a Segment to the Feature. This then allows you to override the flag value for Users that are within that Segment. If the Identified user is a member of that Segment, the flag will be overridden.
For all the Feature Flags that relate to Beta features, you can associate this
Beta Users segment with each Flag, and
set the Flag value to
true for that Segment. To do this, edit the Feature Flag and select the segment in the 'Segment
Overrides' drop down.
At this point, all users who log in with an email address that contains
@flagsmith.com will have all Beta features
Let's say that you then partner with another company who need access to all Beta features. You can then simply modify the Segment rules:
Now all users who log in with a
@solidstategroup.com email address are automatically included in beta features.
You can also create Segments within a Feature. This means that only that Feature can make use of that Segment. Feature Specific Segments are useful when you know you will only need to use that Segment definition once. Go to the Feature, then the Segment Overrides Tab, and click the "Create Feature-Specific Segment" button.
If you are using Multi-Variate Flag Values, you can also override the individual value weightings as part of a Segment override.
The full set of Flagsmith rule operators are as follows:
Exactly Matches (=)
Does Not Match (!=)
Does Not Contain
All of the operators act as you would expect. Some of the operators also have special powers!
The following SemVer operators are also available:
For example, if you are using the SemVer system to version your application, you can store the version as a
Flagsmith and then create a rule that looks like, for example:
This Segment rule will include all users running version
4.2.52 or greater of your application.
When you store Trait values against an Identity, they are stored in our API with an associated type:
When you define a Segment rule, the value is stored as a String. When the Segment engine runs, the rule value will be coerced into the type of the Trait value. Here are some examples.
So here you are storing a native
boolean value against the Identity. You can then define a Segment rule, e.g.
accepted_cookies=true. Because the Identity trait named
accepted_cookies is a boolean, the Segment engine will
coerce the string value from
accepted_cookies=true into a boolean, and things will work as expected.
If you were to then change the trait value to a String at a later point the Segment engine will continue to work, because the Identity's Trait value has been stored as a String
For evaluating booleans, we evaluate the following 'truthy' String values as
Percentage Split Operator
The percentage split operator only comes into effect if you are getting the Flags for a particular Identity. If you are just retrieving the flags for an Environment without passing in an Identity, your user will never be included in the percentage split segment.
This operator performs modulo operation. This operator accepts rule
divisor|remainder format and is applicable for Traits having
float values. For example:
This segment rule will include all identities having
userId trait and having a remainder equal to 0
after being divided by 2.
userId % 2 == 0
Feature Flag and Remote Config Precedence
Feature Flag states and Remote Config values can be defined in 3 different places:
- The default Flag/Config value itself
- The Segment associated with the Flag/Config
- Overridden at an Identity level
For example, a Feature Flag
Show Paypal Checkout could be set to
false on the Flag itself,
true in the Beta Users
segment, and then overridden as
false for a specific Identity.
In order to deal with this situation, there is an order of priority:
- If the Identity has an override value, this is returned ahead of Segments and Flags/Config
- If there's no Identity override, the Segment is checked and returned if valid
- If no Identity or Segment overrides the value, the default Flag/Config value is used
More simply, the order of precedence is: