Dear Velocity Team,
I hope this message finds you well.
I'm currently using Apache Velocity in my Java application, and I noticed a
behavioral difference in template rendering when upgrading from version
*2.3* to *2.4.1*.
Template:
{
"students" : $student.values
}
Sample JSON (studentData):
{
"student": {
"values": [
{ "id": 1, "name": "Alice", "age": 20, "grade": "A" },
{ "id": 2, "name": "Bob", "age": 21, "grade": "B" }
]
}
}
Output in Velocity 2.3:
{
"students" : [{id=1, name=Alice, age=20, grade=A}, {id=2, name=Bob,
age=21, grade=B}]
}
Output in Velocity 2.4.1:
{
"students" : [[{id=1, name=Alice, age=20, grade=A}, {id=2, name=Bob,
age=21, grade=B}]]
}
Concern:
In *2.4.1*, the result includes an extra set of brackets, indicating that
Velocity is now treating the .values object as a list containing a list
instead of a list itself.
This change in behavior breaks backward compatibility in my use case. I'm
unsure if this change was intentional or a regression.
Screenshots:
I’ve attached screenshots of the same Java code executed with both versions:
-
*velocity-2.3*
- [image: Screenshot from 2025-07-22 18-38-28.png]
-
*velocity-2.4.1*
- [image: Screenshot from 2025-07-22 18-39-00.png]
Request:
Could you please clarify if this is:
-
An intended change in how Velocity handles map values, or
-
A bug introduced in the recent release?
Additionally, if there's a recommended workaround or best practice for
handling this in 2.4.1, I’d greatly appreciate the guidance.
Thanks for maintaining such a helpful project!
Best regards,
*Ravi Mergu*
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