# Check and validation

If you need to check and validate a rule against a specific payload, you can leverage the public endpoint:

```http
https://{{your_domain}}.commercelayer.io/api/rules/check
```

Where `{{your_domain}}` is the unique subdomain of a Commerce Layer organization for which the Rules Engine is enabled.

To do that you just need to send a `POST` request using a [sales channel](/core/api-credentials.md#sales-channel) or [integration](/core/api-credentials.md#integration) access token and passing the rules you want to check along with the payloads you want the rules to be checked against:

<table><thead><tr><th>Key</th><th>Type<select><option value="0tOVaHhl0kPK" label="Boolean" color="blue"></option><option value="bZn10C3e8Imv" label="Float" color="blue"></option><option value="n9cxwfQTAZAq" label="Integer" color="blue"></option><option value="mwIP7D7F2x7f" label="String" color="blue"></option><option value="QON3NYOTHI8S" label="Array" color="blue"></option><option value="la9depxKXGAy" label="Object" color="blue"></option></select></th><th>Description</th></tr></thead><tbody><tr><td><strong><code>payload</code></strong></td><td><span data-option="QON3NYOTHI8S">Array</span></td><td>An array of objects containing the resource payload(s) you want the <code>rules</code> to be checked against.</td></tr><tr><td><strong><code>rules</code></strong></td><td><span data-option="QON3NYOTHI8S">Array</span></td><td>An array of objects containing the rules you want to check against the <code>payload</code>.</td></tr></tbody></table>

You'll get in the response all the rules outcomes information, including:

* The overall matching result of the rules.
* The list of all the conditions matchers.
* The list of single resources on which the related actions will be applied.
* Any errors.

... and more.

## Example

### Check and outcomes

{% tabs %}
{% tab title="Request" %}
The following request checks the outcomes of a rule that should apply a 3% discount to the total amount of the orders paid by credit card against two different order payloads:

<pre class="language-bash"><code class="lang-bash">curl -g -X POST \
  'https://{{your_domain}}.commercelayer.io/api/rules/check' \
  -H 'Accept: application/vnd.api+json' \
  -H 'Authorization: Bearer your-access-token' \
  -H 'Content-Type: application/vnd.api+json' \
  -d '{
<strong>    "payload": [
</strong>      {
        "order": {
          "id": "oKkhYLlzgE",
          "payment_method": {
            "id": "gnYtPpKLeG",
<strong>            "payment_source_type": "credit_cards"
</strong>          }
        }
      },
      {
        "order": {
          "id": "DgkhGJlzgf",
          "payment_method": {
                    "id": "snXtWdKLdC",
<strong>                    "payment_source_type": "wire_transfers"
</strong>                }
            }
        }
    ],
<strong>    "rules": [
</strong>      {
        "name": "Discount 3% if paid by credit card",
        "conditions": [
          {
            "field": "order.payment_method.payment_source_type",
            "matcher": "eq",
<strong>            "value": "credit_cards",
</strong>            "group": "discountable-orders"
          }
        ],
        "actions": [
          {
            "type": "percentage",
            "selector": "order",
<strong>            "value": 0.03,
</strong>            "groups": [ "discountable-orders" ]
          }
        ]
      }
    ]
  }'
</code></pre>

{% endtab %}

{% tab title="Response" %}
The response code is `200 OK` and the response payload shows the outcomes of the rule's application:

* The overall rule matches because one of the two orders in the payload was paid by credit card. The order and related payment method IDs are listed within the `conditions.matches` array.
* The 3% percentage discount is applied to the order paid by credit card only (`oKkhYLlzgE`), as you can see from the `actions.resources` array.

<pre class="language-json"><code class="lang-json">{
  "data": [
    {
      "id": "x123y456-7zk8-9012-x34y-56789z0123kx",
      "name": "Discount 3% if paid by credit card",
      "priority": 0,
<strong>      "match": true,
</strong>      "conditions_logic": "and",
      "conditions": [
        {
          "field": "order.payment_method.payment_source_type",
          "matcher": "eq",
          "value": "credit_cards",
          "group": "discountable-orders"
<strong>          "match": true,
</strong><strong>          "matches": [
</strong>            {
<strong>              "order": "oKkhYLlzgE",
</strong><strong>              "payment_method": "gnYtPpKLeG",
</strong>              "group": "discountable-orders"
            }
          ],
          "scope": "any"
        }
      ],
      "actions": [
        {
          "resources": [
            {
              "resource_type": "orders",
<strong>              "id": "oKkhYLlzgE",
</strong>              "group": "discountable-orders",
              "quantity": null,
<strong>              "value": 0.03,
</strong><strong>              "action_type": "percentage"
</strong>            }
          ]
        }
      ]
    }
  ]
}
</code></pre>

{% endtab %}
{% endtabs %}

### Validation and errors

{% tabs %}
{% tab title="Request" %}
The following request checks the outcomes of a couple of rules that should apply a 3% discount to the total amount of the orders paid by credit card and a 1000 cents fixed amount discount to the total amount of the orders that have more than two SKUs, but the rule payloads contain some errors:

* The first rule's field is `payment_source` (a wrong attribute that doesn't exist in the Core API's [payment method](/core-api-reference/payment_methods/object.md) resource object) instead of `payment_source_type`.
* The [format](/rules-engine/actions/types/percentage.md#value) of the percentage discount value in the first rule is incorrect.
* The type of action in the second rule is `fixed` (which doesn't exist among the available action types) instead of `fixed_amount`.

<pre class="language-bash"><code class="lang-bash">curl -g -X POST \
  'https://{{your_domain}}.commercelayer.io/api/rules/check' \
  -H 'Accept: application/vnd.api+json' \
  -H 'Authorization: Bearer your-access-token' \
  -H 'Content-Type: application/vnd.api+json' \
  -d '{
    "payload": [
      {
        "order": {
          "id": "oKkhYLlzgE",
          "payment_method": {
            "id": "gnYtPpKLeG",
            "payment_source_type": "credit_cards"
          }
        }
      },
      {
        "order": {
          "id": "DgkhGJlzgf",
          "payment_method": {
            "id": "snXtWdKLdC",
            "payment_source_type": "wire_transfers"
          }
        }
      }
    ],
<strong>    "rules": [
</strong>      {
        "name": "Discount 3% if paid by credit card",
        "conditions": [
          {
<strong>            "field": "order.payment_method.payment_source",
</strong>            "matcher": "eq",
            "value": "credit_cards",
            "group": "paid-by-cc"
          }
        ],
        "actions": [
          {
            "type": "percentage",
            "selector": "order",
<strong>            "value": "3%",
</strong>            "groups": [ "paid-by-cc" ]
          }
        ]
      },
      {
        "name": "Discount 1000 cents if order has > 2 items",
        "conditions": [
          {
            "field": "order.skus_count",
            "matcher": "gt",
            "value": 2,
            "group": "min-num-items"
          }
        ],
        "actions": [
          {
<strong>            "type": "fixed",
</strong>            "selector": "order",
            "value": 1000,
            "groups": [ "min-num-items" ]
          }
        ]
      }
    ]
  }'
</code></pre>

{% endtab %}

{% tab title="Response" %}
The response code is `400 Bad request` and the response payload details all the errors, with a reference to the malformed rule in the `title` key:

<pre class="language-json"><code class="lang-json">{
  "errors": [
    {
      "title": "Discount 3% if paid by credit card",
<strong>      "detail": "Field 'payment_source' is not valid for 'payment_method' in path: 'order.payment_method.payment_source'.",
</strong>      "code": "BAD_REQUEST"
    },
    {
      "title": "Discount 3% if paid by credit card",
<strong>      "detail": "Actions value must be a float with a maximum of 4 decimals, between 0 and 1 (inclusive).",
</strong>      "code": "BAD_REQUEST"
    },
    {
      "title": "Discount 1000 cents if order has > 2 items",
<strong>      "detail": "Actions action type must be one of: percentage, fixed_amount, fixed_price, buy_x_pay_y, every_x_discount_y.",
</strong>      "code": "BAD_REQUEST"
    }
  ]
}
</code></pre>

{% endtab %}
{% endtabs %}

{% hint style="success" %}
If you just need to validate the syntax of one or more rules, you can pass an empty object in the payload array `"payload": [ { } ]`. If you get a `200 OK` response code, it means that the rule is syntactically correct. Otherwise, the errors will be listed in the response with a `400 Bad request` status code.
{% endhint %}


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```
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