Deployment of the API Proxy failed with error "Both the operands for EQUALS expression should be data expressions"

[adevegowda]

The deployment of the API Proxy is failing with the error "Both the operands for EQUALS expression should be data expressions".

What is the cause for this error ?

[adevegowda · Accepted solution]

1. Looked into the Message Processor logs and found the following stack trace corresponding to this error:

   2018-06-01 13:55:17,796 org:myorg env:dev  Apigee-Main-246 ERROR STARTUP_RUNTIME_ERROR - Application.sync() :  sync error for ErrorResponseLogging and revision 1
   2018-06-01 13:55:17,797 org:myorg env:dev  Apigee-Main-246 ERROR STARTUP_RUNTIME_ERROR - Application.sync() :  Actual Error
   com.apigee.expressions.parser.ParseException: Both the operands for EQUALS expression should be data expressions
           at com.apigee.expressions.parser.ExpressionParser.buildExpressionTree(ExpressionParser.java:337) ~[expressions-1.0.0.jar:na]
           at com.apigee.expressions.parser.ExpressionParser.parse(ExpressionParser.java:24) ~[expressions-1.0.0.jar:na]
           at com.apigee.expressions.parser.ExpressionParser.parseLogicExpression(ExpressionParser.java:28) ~[expressions-1.0.0.jar:na]
           at com.apigee.messaging.runtime.Step.getExpression(Step.java:67) ~[message-processor-1.0.0.jar:na]
           at com.apigee.messaging.runtime.Step.handleAdd(Step.java:58) ~[message-processor-1.0.0.jar:na]
           at com.apigee.messaging.runtime.SharedFlowRuntime.addStep(SharedFlowRuntime.java:81) ~[message-processor-1.0.0.jar:na] 
   … <snipped>
   

2. The error message in the ParseException - "Both the operands for EQUALS expression should be data expressions" indicated that a condition involving equal to (=), not equal to (!=) or Stats with (=|) operator must be having some issue.
3. So I checked all the Conditional Expressions used and found the problem in the following line:

   <Condition>(error.state != null) and (productId === 'PayApp')</Condition>
   

4. The error was thrown because "===" was used instead of "=="
5. Modified this line as follows:

   <Condition>(error.state != null) and (productId == 'PayApp')</Condition>
   

6. Saved the changes and deployed the API Proxy again.

With this change, the deployment went through successfully.