Grails 6.2.0 - Cast Exception if Action takes Command

[jdaugherty]

Expected Behavior

After upgrading to Grails 6.2.0, one of our controllers started to error. I was able to reproduce this issue in a sample application. Visiting http://localhost:8080/example/list should render the list action renders without issue. Instead an exception is thrown.

Changing a variable name in an unrelated action fixes the issue.

Actual Behaviour

A class cast exception occurs:

Cannot cast object 'brokenBinding.ExampleSearchCommand@116e5496' with class 'brokenBinding.ExampleSearchCommand' to class 'brokenBinding.ExampleCommand'

Steps To Reproduce

Details in README.md

1. Launch grails app
2. Visit http://localhost:8080/example/list

Environment Information

• Operating System: Mac OS 14.4.1 & Latest Stable Linux (Debian)
• JDK: 11.0.22 Liberica (.sdkmanrc has version in example project)

Example Application

https://github.com/jdaugherty/grails-broken-binding

Version

6.2.0

[jdaugherty]

Here's a screenshot of the byte code generated by Grails for the list action that gets created to handle command object creation:

I've circled in red what's causing the cast exception.

[matrei]

That is interesting! Could you also post the generated code when the variable is renamed?

[jdaugherty]

If I rename the variable in the edit action, here's the generated code of the list action:

[jdaugherty]

This behavior wasn't present in our project for Grails 5.x. We first noticed it when we updated to Grails 6.x.

[rick-boardontrack]

FYI: I ran into this too.

I found that if I use the method parameter name 'cmd' for the command object, then it fails:

def save(AssessmentCommand cmd) {

produces the org.codehaus.groovy.runtime.typehandling.GroovyCastException when I call save().

But when changing the parameter named to 'acmd', everything works as expected:

def save(AssessmentCommand acmd) {

[rick-boardontrack]

I've learned a bit more... it is not JUST the name. I have another case where the name of the parameter is 'cmd' and it works just fine.