PostHog.FeatureFlags.Result (posthog v2.9.1)

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Represents the result of a feature flag evaluation.

This struct contains all the information returned when evaluating a feature flag:

  • key - The name of the feature flag
  • enabled - Whether the flag is enabled for this user
  • variant - The variant assigned to this user (nil for boolean flags)
  • payload - The JSON payload configured for this flag/variant (nil if not set)
  • id - Numeric flag ID from the PostHog backend (when available)
  • version - Flag version from the PostHog backend (when available)
  • reason - Reason map describing why this evaluation produced its value
  • request_id - Request ID returned by the /flags endpoint (useful for experiment exposure tracking)
  • evaluated_at - Server-side evaluation timestamp from the response
  • errors_while_computing - Whether the response signaled errorsWhileComputingFlags; values for some flags may be incomplete or stale. Forwarded as $feature_flag_error: "errors_while_computing_flags" on $feature_flag_called events.

The metadata fields are populated when the /flags response includes them and are forwarded as $feature_flag_id, $feature_flag_version, $feature_flag_reason, $feature_flag_request_id, and $feature_flag_evaluated_at properties on $feature_flag_called events.

Examples 

# Boolean flag result
%PostHog.FeatureFlags.Result{
  key: "my-feature",
  enabled: true,
  variant: nil,
  payload: nil
}

# Multivariant flag result with payload and metadata
%PostHog.FeatureFlags.Result{
  key: "my-experiment",
  enabled: true,
  variant: "control",
  payload: %{"button_color" => "blue"},
  id: 154_429,
  version: 4,
  reason: %{"code" => "condition_match", "description" => "Matched condition set 1"},
  request_id: "0d23f243-399a-4904-b1a8-ec2037834b72",
  evaluated_at: 1_234_567_890
}

Summary

Types

json()

JSON-compatible value used for feature flag payloads.

t()

Result for a single evaluated feature flag.

Functions

value(result)

Returns the value of the feature flag result.

Types

json()

@type json() ::
  String.t()
  | number()
  | boolean()
  | nil
  | [json()]
  | %{required(String.t()) => json()}

JSON-compatible value used for feature flag payloads.

t()

@type t() :: %PostHog.FeatureFlags.Result{
  enabled: boolean(),
  errors_while_computing: boolean(),
  evaluated_at: integer() | nil,
  id: integer() | nil,
  key: String.t(),
  payload: json(),
  reason: map() | nil,
  request_id: String.t() | nil,
  variant: String.t() | nil,
  version: integer() | nil
}

Result for a single evaluated feature flag.

The struct fields mirror the data returned by PostHog's /flags endpoint and the metadata emitted on $feature_flag_called events.

Functions

value(result)

@spec value(t()) :: boolean() | String.t()

Returns the value of the feature flag result.

If a variant is present, returns the variant string. Otherwise, returns the enabled boolean status. This provides backwards compatibility with existing code that expects a simple value from feature flag checks.

Examples 

iex> result = %PostHog.FeatureFlags.Result{key: "flag", enabled: true, variant: "control", payload: nil}
iex> PostHog.FeatureFlags.Result.value(result)
"control"

iex> result = %PostHog.FeatureFlags.Result{key: "flag", enabled: true, variant: nil, payload: nil}
iex> PostHog.FeatureFlags.Result.value(result)
true

iex> result = %PostHog.FeatureFlags.Result{key: "flag", enabled: false, variant: nil, payload: nil}
iex> PostHog.FeatureFlags.Result.value(result)
false