How to add RegEx validations in Azure API Management Policy Expression

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: