Types and Data Structures
Overview
This document outlines some of the common types and data structures defined by OpenFeature and referenced elsewhere in this specification.
Boolean
A logical true or false, as represented idiomatically in the implementation languages.
String
A UTF-8 encoded string.
Number
A numeric value of unspecified type or size. Implementation languages may further differentiate between integers, floating point numbers, and other specific numeric types and provide functionality as idioms dictate.
Structure
Structured data, presented however is idiomatic in the implementation language, such as JSON or YAML.
Datetime
A language primitive for representing a date and time, optionally including timezone information. If no timezone is specified, the date and time will be treated as UTC.
Evaluation Details
A structure representing the result of the flag evaluation process, and made available in the detailed flag resolution functions, containing the following fields:
- flag key (string, required)
- value (boolean | string | number | structure, required)
- error code (error code, optional)
- error message (string, optional)
- reason (string, optional)
- variant (string, optional)
- flag metadata (flag metadata)
Resolution Details
A structure which contains a subset of the fields defined in the evaluation details, representing the result of the provider's flag resolution process, including:
- value (boolean | string | number | structure, required)
- error code (error code, optional)
- error message (string, optional)
- reason (string, optional)
- variant (string, optional)
- flag metadata (flag metadata, optional)
A set of pre-defined reasons is enumerated below:
| Reason | Explanation |
|---|---|
| STATIC | The resolved value is static (no dynamic evaluation). |
| DEFAULT | The resolved value fell back to a pre-configured value (no dynamic evaluation occurred or dynamic evaluation yielded no result). |
| TARGETING_MATCH | The resolved value was the result of a dynamic evaluation, such as a rule or specific user-targeting. |
| SPLIT | The resolved value was the result of pseudorandom assignment. |
| CACHED | The resolved value was retrieved from cache. |
| DISABLED | The resolved value was the result of the flag being disabled in the management system. |
| UNKNOWN | The reason for the resolved value could not be determined. |
| ERROR | The resolved value was the result of an error. |
NOTE: The
resolution detailsstructure is not exposed to the Application Author. It defines the data which Provider Authors must return when resolving the value of flags.
Error Code
An enumerated error code represented idiomatically in the implementation language.
| Error Code | Explanation |
|---|---|
| PROVIDER_NOT_READY | The value was resolved before the provider was ready. |
| FLAG_NOT_FOUND | The flag could not be found. |
| PARSE_ERROR | An error was encountered parsing data, such as a flag configuration. |
| TYPE_MISMATCH | The type of the flag value does not match the expected type. |
| TARGETING_KEY_MISSING | The provider requires a targeting key and one was not provided in the evaluation context. |
| INVALID_CONTEXT | The evaluation context does not meet provider requirements. |
| GENERAL | The error was for a reason not enumerated above. |
Evaluation Options
A structure containing the following fields:
- hooks (one or more hooks, optional)
Flag Metadata
A structure which supports definition of arbitrary properties, with keys of type string, and values of type boolean, string, or number.
This structure is populated by a provider for use by an Application Author (via the Evaluation API) or an Application Integrator (via hooks).