How to add custom header in Azure API Management before making a call to the backend - azure

Question

I have an Rest Api that is being exposed on Azure. The Azure Api once called calls a WCF Service in the backend.
Firstly I need to transform the JSON Request to XML. Also, To call the SOAP Service I need to add a Custom Header like this:-
<s:Header>
<AuthHeader xmlns="http://abc.security.service">
<UserID>UserID</UserID>
<Token>Token</Token>
</AuthHeader>
</s:Header>
How do I add an "Inbound Policy" that would transform the request to XML and inject the custom header ?
Any ideas or suggestions would be greatly appreciated !!

Answer 1

For this requirement, please refer to the policy in my APIM.
<policies>
<inbound>
<base />
<json-to-xml apply="always" />
<set-body>#{
string inBody = context.Request.Body.As<string>();
string requestBody = inBody.Replace("<Document>","").Replace("</Document>","");
string header = "<s:Header><AuthHeader xmlns=\"http://abc.security.service\"><UserID>UserID</UserID><Token>Token</Token></AuthHeader></s:Header>";
return header + requestBody;
}</set-body>
</inbound>
<backend>
<base />
</backend>
<outbound>
<base />
</outbound>
<on-error>
<base />
</on-error>
</policies>
Please pay attention to the escape character in header, we need to use \" instead of ".