How to validate input and raise fault in Apigee

Question

How can I validate an input to APIGee endpoint and raise a fault if input is not provided or if it is not in a valid format?

For eg: I am expecting a value to be passed in querystring. If its not supplied, I should return a error response instead of letting it pass through back-end service and fail there.

Thanks, Deepak

Answer 1

To accomplish this, add a Condition to the RaiseFault Policy.

For example:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ProxyEndpoint name="default">
    <Description/>
    <Flows/>
    <PreFlow name="PreFlow">
        <Request>
            <Step>
                <FaultRules/>
                <Name>RaiseFault-1</Name>
                <Condition>request.queryparam.myParam == null</Condition>
            </Step>
        </Request>
        <Response/>
    </PreFlow>
    <HTTPProxyConnection>
        <BasePath>/myBasePath</BasePath>
        <VirtualHost>default</VirtualHost>
        <VirtualHost>secure</VirtualHost>
    </HTTPProxyConnection>
    <RouteRule name="default">
        <TargetEndpoint>default</TargetEndpoint>
    </RouteRule>
    <PostFlow name="PostFlow">
        <Request/>
        <Response/>
    </PostFlow>
</ProxyEndpoint>