How to add RegEx validations in Azure API Management Policy Expression - regex

Question

I need to add a RegEx validation for email in my Azure API Management Policy expression but there is no proper documentation available.
Is it possible to have RegEx validation in Azure APIM?

Answer 1

This can be done by setting a variable with C# regex code.
The variable can be used in the choose policy for further processing
Complete policy return result of regex match:
<policies>
<inbound>
<base />
<set-variable name="isEMailValid" value="#{
var pattern = #"^((([!#$%&'*+\-/=?^_`{|}~\w])|((?!.*\.\.)[!#$%&'*+\-/=?^_`{|}~\w][!#$%&'*+\-/=?^_`{|}~\.\w]{0,}[!#$%&'*+\-/=?^_`{|}~\w]))[#]\w+([-.]\w+)*\.\w+([-.]\w+)*)$";
var body = (JObject)context.Request.Body.As<JObject>(true);
var regex = new Regex(pattern);
if(regex.Match(body["email"].Value<string>()).Success)
{
return true;
}
return false;
}" />
<return-response>
<set-status code="200" reason="OK" />
<set-header name="Content-Type" exists-action="override">
<value>application/json</value>
</set-header>
<set-body>#{
var response = new JObject();
response["isEMailValid"] = context.Variables.GetValueOrDefault<bool>("isEMailValid");
return response.ToString();
}</set-body>
</return-response>
</inbound>
<backend>
<base />
</backend>
<outbound>
<base />
</outbound>
<on-error>
<base />
</on-error>
</policies>
Request valid:
POST https://rfqapiservicey27itmeb4cf7q.azure-api.net/sample/ipsum HTTP/1.1
Host: rfqapiservicey27itmeb4cf7q.azure-api.net
{ "email": "a#b.com"}
Response valid:
HTTP/1.1 200 OK
content-length: 28
content-type: application/json
date: Fri, 03 Feb 2023 07:15:32 GMT
vary: Origin
{
"isEMailValid": true
}
Request invalid: