Evaluate flags for context instance

For the complete documentation index, see llms.txt. For the full documentation snapshot, see llms-full.txt.

Evaluate flags for a context instance, for example, to determine the expected flag variation. Do not use this API instead of an SDK. The LaunchDarkly SDKs are specialized for the tasks of evaluating feature flags in your application at scale and generating analytics events based on those evaluations. This API is not designed for that use case. Any evaluations you perform with this API will not be reflected in features such as flag statuses and flag insights. Context instances evaluated by this API will not appear in the Contexts list. To learn more, read Comparing LaunchDarkly’s SDKs and REST API.

Filtering

LaunchDarkly supports the filter query param for filtering, with the following fields:

• query filters for a string that matches against the flags’ keys and names. It is not case sensitive. For example: filter=query equals dark-mode.
• tags filters the list to flags that have all of the tags in the list. For example: filter=tags contains ["beta","q1"].

You can also apply multiple filters at once. For example, setting filter=query equals dark-mode, tags contains ["beta","q1"] matches flags which match the key or name dark-mode and are tagged beta and q1.

POST /api/v2/projects/{projectKey}/environments/{environmentKey}/flags/evaluate

Evaluate flags for context instance

cURL

curl --request POST \
  --url https://app.launchdarkly.com/api/v2/projects/{projectKey}/environments/{environmentKey}/flags/evaluate \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "key": "user-key-123abc",
  "kind": "user",
  "otherAttribute": "other attribute value"
}
'

200

{
  "items": [
    {
      "_links": {
        "self": {
          "href": "/api/v2/projects/{projectKey}/environments/{environmentKey}/flags/evaluate",
          "type": "application/json"
        },
        "site": {
          "href": "/my-project/my-environment/features/sort.order/targeting",
          "type": "text/html"
        }
      },
      "_value": true,
      "key": "sort.order",
      "name": "SortOrder",
      "reason": {
        "kind": "FALLTHROUGH"
      }
    },
    {
      "_links": {
        "self": {
          "href": "/api/v2/projects/{projectKey}/environments/{environmentKey}/flags/evaluate",
          "type": "application/json"
        },
        "site": {
          "href": "/my-project/my-environment/features/alternate.page/targeting",
          "type": "text/html"
        }
      },
      "_value": false,
      "key": "alternate.page",
      "name": "AlternatePage",
      "reason": {
        "kind": "RULE_MATCH",
        "ruleID": "b2530cdf-14c6-4e16-b660-00239e08f19b",
        "ruleIndex": 1
      }
    }
  ],
  "_links": {
    "self": {
      "href": "/api/v2/projects/{projectKey}/environments/{environmentKey}/flags/evaluate",
      "type": "application/json"
    }
  },
  "totalCount": 2
}

Authorizations

Authorization · string · header · required

Path Parameters

projectKey · string<string> · required

The project key

environmentKey · string<string> · required

The environment key

Query Parameters

limit · integer<int64>

The number of feature flags to return. Defaults to -1, which returns all flags

offset · integer<int64>

Where to start in the list. Use this with pagination. For example, an offset of 10 skips the first ten items and then returns the next items in the list, up to the query limit.

sort · string<string>

A comma-separated list of fields to sort by. Fields prefixed by a dash ( - ) sort in descending order

filter · string<string>

A comma-separated list of filters. Each filter is of the form field operator value. Supported fields are explained above.

Body

application/json

{key} · any

Response

200

application/json

Flag evaluation collection response

items · object[] · required

Details on the flag evaluations for this context instance

Show child attributes

Example:

[
  {
    "_links": {
      "self": {
        "href": "/api/v2/projects/{projectKey}/environments/{environmentKey}/flags/evaluate",
        "type": "application/json"
      },
      "site": {
        "href": "/my-project/my-environment/features/sort.order/targeting",
        "type": "text/html"
      }
    },
    "_value": true,
    "key": "sort.order",
    "name": "SortOrder",
    "reason": { "kind": "FALLTHROUGH" }
  },
  {
    "_links": {
      "self": {
        "href": "/api/v2/projects/{projectKey}/environments/{environmentKey}/flags/evaluate",
        "type": "application/json"
      },
      "site": {
        "href": "/my-project/my-environment/features/alternate.page/targeting",
        "type": "text/html"
      }
    },
    "_value": false,
    "key": "alternate.page",
    "name": "AlternatePage",
    "reason": {
      "kind": "RULE_MATCH",
      "ruleID": "b2530cdf-14c6-4e16-b660-00239e08f19b",
      "ruleIndex": 1
    }
  }
]

_links · object · required

The location and content type of related resources

Show child attributes

Example:

{
  "self": {
    "href": "/api/v2/projects/{projectKey}/environments/{environmentKey}/flags/evaluate",
    "type": "application/json"
  }
}

totalCount · integer

The number of flags

Example:

2