How do I check for the well formed XML or JSON

Google Cloud Apigee
1

Hi,

I want to check if the JSON or XML are well formed and raise an error if they are not. Please suggest the ways I can do this in Edge.

2

Checkout SOAPMessageValidation policy - https://docs.apigee.com/api-platform/reference/policies/message-validation-policy#3:-well-formed-xmljson; name of the policy may be confusing but you can use this policy to confirm that a JSON or XML message payload is well-formed (not the same as validation).

1 Like
3

If JSON, you can run a JS policy that simply performs JSON.parse().

If it works, then it is well formed.

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4

Yes, it worked. Thank you

5

@Kuldeep Bhati We would need WSDL or XSD to validate XML using this policy? For JSON, I used JSON.parse() as suggsted by Dino.

6

Hi @Shivakumar Sudi, yes I understand that, however XSD/WSDL is required for XML/SOAP message, not for JSON.

JSON Validation - Use the snippet mentioned below / also on documentation here - https://docs.apigee.com/api-platform/reference/policies/message-validation-policy#3:-well-formed-xmljson

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<MessageValidation async="false" continueOnError="false" enabled="true" name="validateXMLorJSONRequest">
    <DisplayName>validateXMLorJSONRequest</DisplayName>
    <Properties/>
    <Source>request</Source>
</MessageValidation><br>

XML Validation - Use the snippet mentioned below / also on documentation here - https://docs.apigee.com/api-platform/reference/policies/message-validation-policy#1:-xsd-validation

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<MessageValidation async="false" continueOnError="false" enabled="true" name="validateXMLRequest">
    <DisplayName>validateXMLRequest</DisplayName>
    <Properties/>
    <Source>request</Source>
    <ResourceURL>xsd://note-schema.xsd</ResourceURL>
</MessageValidation>

I have just tested the both XML and well-formed JSON, check the attached sample proxy I just tried - xmljsonmessagevalidationproxy-v1-rev5-2019-03-22.zip deploy this proxy and test with curl command mentioned below for both JOSN/XML;

Use this curl call to test this proxy for JSON validation - where {proxy-endpoint} is your apigee proxy endpoint, e.g. http://{org}-{env}.apigee.net

curl -X POST \
  {proxy-endpoint}/v1/validate-json-xml-message/echo \
  -H 'Content-Type: application/json' \
  -d '{
  "to": "Fred Rogers",
  "from": "Nick Danger",
  "header": "Greetings from my neighborhood",
  "body": "Just writing to say hello."
}'<br>

Use this curl call to test this proxy for XML validation - where {proxy-endpoint} is your apigee proxy endpoint, like

curl -X POST \
  {proxy-endpoint}/v1/validate-json-xml-message/echo \
  -H 'Content-Type: application/xml' \
  -d '<note>
  <to>Fred Rogers</to>
  <from>Nick Danger</from>
  <heading>Greetings from my neighborhood</heading>
  <body>Just writing to say hello.</body>
</note>'

I recommend using “SOAP Message Validation” and other OOTB policies over Javascript anyday, here’s the explanation -

https://docs.apigee.com/api-platform/samples/cookbook/programming-api-proxies-javascript

I hope this explanation help.

Good luck!

1 Like
7

mmm, yes.. But assessing the validity of an XML document is not what you asked for, is it? You asked about well-formed-ness. Validity is something beyond well-formed-ness.

I would think you could also use the JS policy to assess well-formed ness by attempting to use the asXML property. see here.

var x = context.proxyRequest.content.asXML;
if (x == null) { 
  throw new Error("not an XML document");
}
8

Hey @Dino-at-Google – Any reason you don’t suggest the well-formedness feature of the SOAPMessageValidation policy? https://docs.apigee.com/api-platform/reference/policies/message-validation-policy#3:-well-formed-xmljson