---
title: Set default subject type
description: Datadog, the leading service for cloud-scale monitoring.
breadcrumbs: Docs > API Reference > Experiments
---

> For the complete documentation index, see [llms.txt](https://docs.datadoghq.com/llms.txt).

{% callout %}
# Important note for users on the following Datadog sites: app.ddog-gov.com, us2.ddog-gov.com

{% alert level="danger" %}
This product is not supported for your selected [Datadog site](https://docs.datadoghq.com/getting_started/site.md). ({% placeholder "user-datadog-site-name" /%}).
{% /alert %}

{% /callout %}

# Set default subject type{% #set-default-subject-type %}

{% tab title="v2" %}

| Datadog site      | API endpoint                                                                                  |
| ----------------- | --------------------------------------------------------------------------------------------- |
| ap1.datadoghq.com | POST https://api.ap1.datadoghq.com/api/v2/experiments/subject-types/{subject_type_id}/default |
| ap2.datadoghq.com | POST https://api.ap2.datadoghq.com/api/v2/experiments/subject-types/{subject_type_id}/default |
| app.datadoghq.eu  | POST https://api.datadoghq.eu/api/v2/experiments/subject-types/{subject_type_id}/default      |
| app.ddog-gov.com  | POST https://api.ddog-gov.com/api/v2/experiments/subject-types/{subject_type_id}/default      |
| us2.ddog-gov.com  | POST https://api.us2.ddog-gov.com/api/v2/experiments/subject-types/{subject_type_id}/default  |
| uk1.datadoghq.com | POST https://api.uk1.datadoghq.com/api/v2/experiments/subject-types/{subject_type_id}/default |
| app.datadoghq.com | POST https://api.datadoghq.com/api/v2/experiments/subject-types/{subject_type_id}/default     |
| us3.datadoghq.com | POST https://api.us3.datadoghq.com/api/v2/experiments/subject-types/{subject_type_id}/default |
| us5.datadoghq.com | POST https://api.us5.datadoghq.com/api/v2/experiments/subject-types/{subject_type_id}/default |

### Overview

Make this subject type the organization's default. Experiment creation uses the default when the request names no subject type. Promoting one subject type demotes the previous default in the same transaction, so the organization always has exactly one. The call is idempotent: promoting the current default succeeds and changes nothing. There is no matching demote, because an organization cannot have no default; promote a different subject type instead. This endpoint requires the `product_analytics_settings_write` permission.

OAuth apps require the `product_analytics_settings_write` authorization [scope](https://docs.datadoghq.com/api/latest/scopes.md#experiments) to access this endpoint.



### Arguments

#### Path Parameters

| Name                              | Type   | Description                   |
| --------------------------------- | ------ | ----------------------------- |
| subject_type_id [*required*] | string | The UUID of the subject type. |

### Response

{% tab title="204" %}
The subject type is now the organization's default.
{% /tab %}

{% tab title="400" %}
Malformed subject type ID (not a valid UUID).
{% tab title="Model" %}
API error response.

| Parent field | Field                    | Type     | Description                                                                     |
| ------------ | ------------------------ | -------- | ------------------------------------------------------------------------------- |
|              | errors [*required*] | [object] | A list of errors.                                                               |
| errors       | detail                   | string   | A human-readable explanation specific to this occurrence of the error.          |
| errors       | meta                     | object   | Non-standard meta-information about the error                                   |
| errors       | source                   | object   | References to the source of the error.                                          |
| source       | header                   | string   | A string indicating the name of a single request header which caused the error. |
| source       | parameter                | string   | A string indicating which URI query parameter caused the error.                 |
| source       | pointer                  | string   | A JSON pointer to the value in the request document that caused the error.      |
| errors       | status                   | string   | Status code of the response.                                                    |
| errors       | title                    | string   | Short human-readable summary of the error.                                      |

{% /tab %}

{% tab title="Example" %}

```json
{
  "errors": [
    {
      "detail": "Missing required attribute in body",
      "meta": {},
      "source": {
        "header": "Authorization",
        "parameter": "limit",
        "pointer": "/data/attributes/title"
      },
      "status": "400",
      "title": "Bad Request"
    }
  ]
}
```

{% /tab %}

{% /tab %}

{% tab title="401" %}
Missing or invalid authentication.
{% tab title="Model" %}
API error response.

| Parent field | Field                    | Type     | Description                                                                     |
| ------------ | ------------------------ | -------- | ------------------------------------------------------------------------------- |
|              | errors [*required*] | [object] | A list of errors.                                                               |
| errors       | detail                   | string   | A human-readable explanation specific to this occurrence of the error.          |
| errors       | meta                     | object   | Non-standard meta-information about the error                                   |
| errors       | source                   | object   | References to the source of the error.                                          |
| source       | header                   | string   | A string indicating the name of a single request header which caused the error. |
| source       | parameter                | string   | A string indicating which URI query parameter caused the error.                 |
| source       | pointer                  | string   | A JSON pointer to the value in the request document that caused the error.      |
| errors       | status                   | string   | Status code of the response.                                                    |
| errors       | title                    | string   | Short human-readable summary of the error.                                      |

{% /tab %}

{% tab title="Example" %}

```json
{
  "errors": [
    {
      "detail": "Missing required attribute in body",
      "meta": {},
      "source": {
        "header": "Authorization",
        "parameter": "limit",
        "pointer": "/data/attributes/title"
      },
      "status": "400",
      "title": "Bad Request"
    }
  ]
}
```

{% /tab %}

{% /tab %}

{% tab title="403" %}
Authenticated caller lacks the product_analytics_settings_write permission.
{% tab title="Model" %}
API error response.

| Parent field | Field                    | Type     | Description                                                                     |
| ------------ | ------------------------ | -------- | ------------------------------------------------------------------------------- |
|              | errors [*required*] | [object] | A list of errors.                                                               |
| errors       | detail                   | string   | A human-readable explanation specific to this occurrence of the error.          |
| errors       | meta                     | object   | Non-standard meta-information about the error                                   |
| errors       | source                   | object   | References to the source of the error.                                          |
| source       | header                   | string   | A string indicating the name of a single request header which caused the error. |
| source       | parameter                | string   | A string indicating which URI query parameter caused the error.                 |
| source       | pointer                  | string   | A JSON pointer to the value in the request document that caused the error.      |
| errors       | status                   | string   | Status code of the response.                                                    |
| errors       | title                    | string   | Short human-readable summary of the error.                                      |

{% /tab %}

{% tab title="Example" %}

```json
{
  "errors": [
    {
      "detail": "Missing required attribute in body",
      "meta": {},
      "source": {
        "header": "Authorization",
        "parameter": "limit",
        "pointer": "/data/attributes/title"
      },
      "status": "400",
      "title": "Bad Request"
    }
  ]
}
```

{% /tab %}

{% /tab %}

{% tab title="404" %}
No subject type with this ID exists for the organization.
{% tab title="Model" %}
API error response.

| Parent field | Field                    | Type     | Description                                                                     |
| ------------ | ------------------------ | -------- | ------------------------------------------------------------------------------- |
|              | errors [*required*] | [object] | A list of errors.                                                               |
| errors       | detail                   | string   | A human-readable explanation specific to this occurrence of the error.          |
| errors       | meta                     | object   | Non-standard meta-information about the error                                   |
| errors       | source                   | object   | References to the source of the error.                                          |
| source       | header                   | string   | A string indicating the name of a single request header which caused the error. |
| source       | parameter                | string   | A string indicating which URI query parameter caused the error.                 |
| source       | pointer                  | string   | A JSON pointer to the value in the request document that caused the error.      |
| errors       | status                   | string   | Status code of the response.                                                    |
| errors       | title                    | string   | Short human-readable summary of the error.                                      |

{% /tab %}

{% tab title="Example" %}

```json
{
  "errors": [
    {
      "detail": "Missing required attribute in body",
      "meta": {},
      "source": {
        "header": "Authorization",
        "parameter": "limit",
        "pointer": "/data/attributes/title"
      },
      "status": "400",
      "title": "Bad Request"
    }
  ]
}
```

{% /tab %}

{% /tab %}

{% tab title="429" %}
Too many requests
{% tab title="Model" %}
API error response.

| Field                    | Type     | Description       |
| ------------------------ | -------- | ----------------- |
| errors [*required*] | [string] | A list of errors. |

{% /tab %}

{% tab title="Example" %}

```json
{
  "errors": [
    "Bad Request"
  ]
}
```

{% /tab %}

{% /tab %}

### Code Example

##### 
                  \# Path parameters export subject_type_id="550e8400-e29b-41d4-a716-446655440000" \# Use a Personal Access Token or Service Access Token export DD_BEARER_TOKEN="<PERSONAL_ACCESS_TOKEN OR SERVICE_ACCESS_TOKEN>"  \# Curl command curl -X POST "https://api.datadoghq.com/api/v2/experiments/subject-types/${subject_type_id}/default" \
-H "Authorization: Bearer ${DD_BEARER_TOKEN}" 

                
##### 

```python
"""
Set default subject type returns "The subject type is now the organization's default." response
"""

from os import environ
from datadog_api_client import ApiClient, Configuration
from datadog_api_client.v2.api.experiments_api import ExperimentsApi
from uuid import UUID

configuration = Configuration()
configuration.access_token = environ["DD_BEARER_TOKEN"]
with ApiClient(configuration) as api_client:
    api_instance = ExperimentsApi(api_client)
    api_instance.set_default_subject_type(
        subject_type_id=UUID("550e8400-e29b-41d4-a716-446655440000"),
    )
```

#### Instructions

First [install the library and its dependencies](https://docs.datadoghq.com/api/latest.md?code-lang=python) and then save the example to `example.py` and run following commands:
    DD_SITE="datadoghq.com" DD_BEARER_TOKEN="<PERSONAL_ACCESS_TOKEN OR SERVICE_ACCESS_TOKEN>" python3 "example.py"
##### 

```ruby
# Set default subject type returns "The subject type is now the organization's default." response

require "datadog_api_client"
DatadogAPIClient.configure do |config|
  config.access_token = ENV["DD_BEARER_TOKEN"]
end
api_instance = DatadogAPIClient::V2::ExperimentsAPI.new
api_instance.set_default_subject_type("550e8400-e29b-41d4-a716-446655440000")
```

#### Instructions

First [install the library and its dependencies](https://docs.datadoghq.com/api/latest.md?code-lang=ruby) and then save the example to `example.rb` and run following commands:
    DD_SITE="datadoghq.com" DD_BEARER_TOKEN="<PERSONAL_ACCESS_TOKEN OR SERVICE_ACCESS_TOKEN>" rb "example.rb"
##### 

```rust
// Set default subject type returns "The subject type is now the organization's
// default." response
use datadog_api_client::datadog;
use datadog_api_client::datadogV2::api_experiments::ExperimentsAPI;
use uuid::Uuid;

#[tokio::main]
async fn main() {
    let configuration = datadog::Configuration::new();
    let api = ExperimentsAPI::with_config(configuration);
    let resp = api
        .set_default_subject_type(
            Uuid::parse_str("550e8400-e29b-41d4-a716-446655440000").expect("invalid UUID"),
        )
        .await;
    if let Ok(value) = resp {
        println!("{:#?}", value);
    } else {
        println!("{:#?}", resp.unwrap_err());
    }
}
```

#### Instructions

First [install the library and its dependencies](https://docs.datadoghq.com/api/latest.md?code-lang=rust) and then save the example to `src/main.rs` and run following commands:
    DD_SITE="datadoghq.com" DD_API_KEY="<DD_API_KEY>" DD_APP_KEY="<DD_APP_KEY>" cargo run
##### 

```go
// Set default subject type returns "The subject type is now the organization's default." response

package main

import (
	"context"
	"fmt"
	"os"

	"github.com/DataDog/datadog-api-client-go/v2/api/datadog"
	"github.com/DataDog/datadog-api-client-go/v2/api/datadogV2"
	"github.com/google/uuid"
)

func main() {
	ctx := datadog.NewDefaultContext(context.Background())
	ctx = context.WithValue(ctx, datadog.ContextAccessToken, os.Getenv("DD_BEARER_TOKEN"))
	configuration := datadog.NewConfiguration()
	apiClient := datadog.NewAPIClient(configuration)
	api := datadogV2.NewExperimentsApi(apiClient)
	r, err := api.SetDefaultSubjectType(ctx, uuid.MustParse("550e8400-e29b-41d4-a716-446655440000"))

	if err != nil {
		fmt.Fprintf(os.Stderr, "Error when calling `ExperimentsApi.SetDefaultSubjectType`: %v\n", err)
		fmt.Fprintf(os.Stderr, "Full HTTP response: %v\n", r)
	}
}
```

#### Instructions

First [install the library and its dependencies](https://docs.datadoghq.com/api/latest.md?code-lang=go) and then save the example to `main.go` and run following commands:
    DD_SITE="datadoghq.com" DD_BEARER_TOKEN="<PERSONAL_ACCESS_TOKEN OR SERVICE_ACCESS_TOKEN>" go run "main.go"
##### 

```java
// Set default subject type returns "The subject type is now the organization's default." response

import com.datadog.api.client.ApiClient;
import com.datadog.api.client.ApiException;
import com.datadog.api.client.v2.api.ExperimentsApi;
import java.util.UUID;

public class Example {
  public static void main(String[] args) {
    ApiClient defaultClient = ApiClient.getDefaultApiClient();
    defaultClient.setAccessToken(System.getenv("DD_BEARER_TOKEN"));
    ExperimentsApi apiInstance = new ExperimentsApi(defaultClient);

    try {
      apiInstance.setDefaultSubjectType(UUID.fromString("550e8400-e29b-41d4-a716-446655440000"));
    } catch (ApiException e) {
      System.err.println("Exception when calling ExperimentsApi#setDefaultSubjectType");
      System.err.println("Status code: " + e.getCode());
      System.err.println("Reason: " + e.getResponseBody());
      System.err.println("Response headers: " + e.getResponseHeaders());
      e.printStackTrace();
    }
  }
}
```

#### Instructions

First [install the library and its dependencies](https://docs.datadoghq.com/api/latest.md?code-lang=java) and then save the example to `Example.java` and run following commands:
    DD_SITE="datadoghq.com" DD_BEARER_TOKEN="<PERSONAL_ACCESS_TOKEN OR SERVICE_ACCESS_TOKEN>" java "Example.java"
{% /tab %}