Set body

APPLIES TO: All API Management tiers

Use the set-body policy to set the message body for a request or response. To access the message body you can use the context.Request.Body property or the context.Response.Body, depending on whether the policy is in the inbound or outbound section.

Policy statement

<set-body template="liquid" xsi-nil="blank | null" parse-date="true | false">
    new body value as text
</set-body>

Attributes

For accessing information about the request and response, the Liquid template can bind to a context object with the following properties:

context.
    Request.
        Url
        Method
        OriginalMethod
        OriginalUrl
        IpAddress
        MatchedParameters
        HasBody
        ClientCertificates
        Headers

    Response.
        StatusCode
        Method
        Headers
Url.
    Scheme
    Host
    Port
    Path
    Query
    QueryString
    ToUri
    ToString

OriginalUrl.
    Scheme
    Host
    Port
    Path
    Query
    QueryString
    ToUri
    ToString

Usage

• Policy sections: inbound, outbound, backend
• Policy scopes: global, workspace, product, API, operation
• Gateways: classic, v2, consumption, self-hosted, workspace

Usage notes

• If you're using the set-body policy to return a new or updated body, you don't need to set preserveContent to true because you're explicitly supplying the new body contents.
• Preserving the content of a response in the inbound pipeline doesn't make sense because there's no response yet.
• Preserving the content of a request in the outbound pipeline doesn't make sense because the request has already been sent to the backend at this point.
• If this policy is used when there's no message body, for example in an inbound GET, an exception is thrown.

For more information, see the context.Request.Body, context.Response.Body, and the IMessageBody sections in the Context variable table.

Using Liquid templates with set-body

The set-body policy can be configured to use the Liquid templating language to transform the body of a request or response. This can be effective if you need to completely reshape the format of your message.

Supported Liquid filters

The following Liquid filters are supported in the set-body policy. For filter examples, see the Liquid documentation.

• Abs
• Append
• AtLeast
• AtMost
• Capitalize
• Compact
• Currency
• Date
• Default
• DividedBy
• Downcase
• Escape
• First
• H
• Join
• Last
• Lstrip
• Map
• Minus
• Modulo
• NewlineToBr
• Plus
• Prepend
• Remove
• RemoveFirst
• Replace
• ReplaceFirst
• Round
• Rstrip
• Size
• Slice
• Sort
• Split
• Strip
• StripHtml
• StripNewlines
• Times
• Truncate
• TruncateWords
• Uniq
• Upcase
• UrlDecode
• UrlEncode

Examples

Literal text

<set-body>Hello world!</set-body>

Accessing the body as a string

We're preserving the original request body so that we can access it later in the pipeline.

<set-body>
@{ 
    string inBody = context.Request.Body.As<string>(preserveContent: true); 
    if (inBody[0] =='c') { 
        inBody[0] = 'm'; 
    } 
    return inBody; 
}
</set-body>

Accessing the body as a JObject

Since we're not reserving the original request body, accessing it later in the pipeline will result in an exception.

<set-body> 
@{ 
    JObject inBody = context.Request.Body.As<JObject>(); 
    if (inBody.attribute == <tag>) { 
        inBody[0] = 'm'; 
    } 
    return inBody.ToString(); 
} 
</set-body>

Filter response based on product

This example shows how to perform content filtering by removing data elements from the response received from a backend service when using the Starter product. The example backend response includes root-level properties similar to the OpenWeather One Call API.

<!-- Copy this snippet into the outbound section to remove a number of data elements from the response received from the backend service based on the name of the product -->
<choose>
  <when condition="@(context.Response.StatusCode == 200 && context.Product.Name.Equals("Starter"))">
    <set-body>@{
        var response = context.Response.Body.As<JObject>();
        foreach (var key in new [] {"current", "minutely", "hourly", "daily", "alerts"}) {
          response.Property (key).Remove ();
        }
        return response.ToString();
      }
    </set-body>
  </when>
</choose>

Convert JSON to SOAP using a Liquid template

<set-body template="liquid">
    <soap:Envelope xmlns="http://tempuri.org/" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
        <soap:Body>
            <GetOpenOrders>
                <cust>{{body.getOpenOrders.cust}}</cust>
            </GetOpenOrders>
        </soap:Body>
    </soap:Envelope>
</set-body>

Transform JSON using a Liquid template

<set-body template="liquid">
{
"order": {
    "id": "{{body.customer.purchase.identifier}}",
    "summary": "{{body.customer.purchase.orderShortDesc}}"
    }
}
</set-body>

Access the body as URL-encoded form data

The following example uses the AsFormUrlEncodedContent() expression to access the request body as URL-encoded form data (content type application/x-www-form-urlencoded), and then converts it to JSON. Since we're not reserving the original request body, accessing it later in the pipeline will result in an exception.

<set-body> 
@{ 
    var inBody = context.Request.Body.AsFormUrlEncodedContent();
    return JsonConvert.SerializeObject(inBody); 
} 
</set-body>

Access and return body as URL-encoded form data

The following example uses the AsFormUrlEncodedContent() expression to access the request body as URL-encoded form data (content type application/x-www-form-urlencoded), adds data to the payload, and returns URL-encoded form data. Since we're not reserving the original request body, accessing it later in the pipeline will result in an exception.

<set-body> 
@{ 
    var body = context.Request.Body.AsFormUrlEncodedContent();
    body["newKey"].Add("newValue");
    return body.ToFormUrlEncodedContent(); 
} 
</set-body>

Related policies

• Transformation

Related content

For more information about working with policies, see:

• Tutorial: Transform and protect your API
• Policy reference for a full list of policy statements and their settings
• Policy expressions
• Set or edit policies
• Reuse policy configurations
• Policy snippets repo
• Author policies using Microsoft Copilot in Azure