Evaluating Flags

`GetFlag(key, ctx)`

Returns the data for a specific flag, or nil if the flag does not exist.


flag := client.GetFlag("new-checkout", &canarygate.FlagEvaluationContext{
    UserID: "user-42",
})
// *FlagData or nil

The UserID in the context is used to evaluate rollout flags consistently: the same user always gets the same result. When the context or UserID is empty, a per-instance anonymous ID is used.

Safe check


if flag != nil && flag.Enabled {
    // Flag is enabled for this user
}

`GetFlags(ctx)`

Returns all flags for the environment as a slice.


flags := client.GetFlags(&canarygate.FlagEvaluationContext{UserID: "user-42"})
 
for _, flag := range flags {
    fmt.Println(flag.Key, flag.Enabled)
}

Examples by flag type

Boolean flag


maintenance := client.GetFlag("maintenance-mode", ctx)
if maintenance != nil && maintenance.Enabled {
    return maintenancePage()
}

Rollout flag


newDashboard := client.GetFlag("new-dashboard", ctx)
 
// flag.Enabled is true or false based on userId and percentage
if newDashboard != nil && newDashboard.Enabled {
    return newDashboardPage()
}
 
// To see the configured percentage:
if newDashboard != nil && newDashboard.Type == "rollout" {
    fmt.Printf("%d%% of users will see this feature\n", newDashboard.Percent)
}

Before `Init()`

If you call GetFlag() before Init(), the flag will return nil (the local cache is still empty).


client := canarygate.New("cg_key", canarygate.Options{})
// Do not do this:
client.GetFlag("feature", ctx) // nil
 
// Do this instead:
if err := client.Init(); err != nil {
    log.Fatal(err)
}
client.GetFlag("feature", ctx) // *FlagData or nil

Flags that do not exist

If the flag does not exist in the environment, GetFlag() returns nil. Always guard with a nil check to avoid breaking the application flow:


// If 'new-feature' does not exist in the environment, enabled will be false
enabled := false
if flag := client.GetFlag("new-feature", ctx); flag != nil {
    enabled = flag.Enabled
}

GetFlag(key, ctx)