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Skill 77 · Instrument Feature Flags
Subchapter 77.3
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1
Required
flags is the endpoint used to determine if a given flag is enabled for a certain user or not.
curl -v -L --header "Content-Type: application/json" -d '{
"token": "<ph_project_token>",
"distinct_id": "distinct_id_of_your_user",
"groups" : {
"group_type": "group_id"
}
}' "https://us.i.posthog.com/flags?v=2"import requests
import json
url = "https://us.i.posthog.com/flags?v=2"
headers = {
"Content-Type": "application/json"
}
payload = {
"token": "<ph_project_token>",
"distinct_id": "user distinct id",
"groups": {
"group_type": "group_id"
const response = await fetch("https://us.i.posthog.com/flags?v=2", {
method: "POST",
headers: {
"Content-Type": "application/json",
},
body: JSON.stringify({
token: "<ph_project_token>",
distinct_id: "user distinct id",
groups: {
group_type:
Note: The groups key is only required for group-based feature flags. If you use it, replace group_type and group_id with the values for your group such as company: "Twitter".
2
Required
If you want to use your feature flag to breakdown or filter events in your insights, you’ll need to include feature flag information in those events. This ensures that the feature flag value is attributed correctly to the event.
Note: This step is only required for events captured using our server-side SDKs or API.
curl -v -L --header
3
Optional
To track usage of your feature flag and view related analytics in PostHog, submit the $feature_flag_called event whenever you check a feature flag value in your code.
You need to include two properties with this event:
$feature_flag_response: This is the name of the variant the user has been assigned to e.g., “control” or “test”$feature_flag: This is the key of the feature flag in your experiment.curl
4
Optional
Experiments run on top of our feature flags. Once you’ve implemented the flag in your code, you run an experiment by creating a new experiment in the PostHog dashboard.
5
Recommended
Now that you’re evaluating flags, continue with the resources below to learn what else Feature Flags enables within the PostHog platform.
| Resource | Description |
|---|---|
| Creating a feature flag (opens in a new tab) | How to create a feature flag in PostHog |
| Adding feature flag code (opens in a new tab) | How to check flags in your code for all platforms |
| Framework-specific guides |
Ask PostHog AI
HelpfulCould be better
import requests
import json
url = "https://us.i.posthog.com/i/v0/e/"
headers = {
"Content-Type": "application/json"
}
payload = {
"token": "<ph_project_token>",
"event": "your_event_name",
"distinct_id": "distinct_id_of_your_user",
"properties": {
"$feature/feature-flag-key": "variant-key"
}
}
response = requests.post(url, headers=headers, data=json.dumps(payload))
print(response)import requests
import json
url = "https://us.i.posthog.com/i/v0/e/"
headers = {
"Content-Type": "application/json"
}
payload = {
"token": "<ph_project_token>",
"event": "$feature_flag_called",
"distinct_id": "distinct_id_of_your_user",
"properties": {
"$feature_flag": "feature-flag-key",
"$feature_flag_response": "variant-name"
}
}
response = requests.post(url, headers=headers, data=json.dumps(payload))
print(response)| Setup guides for React Native, Next.js, Flutter, and other frameworks |
| How to do a phased rollout (opens in a new tab) | Gradually roll out features to minimize risk |
| More tutorials (opens in a new tab) | Other real-world examples and use cases |