add method 'toChar[class java.lang.Object]' in class class org.apach…

[pierre-mazieres-semarchy]

When I was working on a dummy Apache Connector (in order to understand how to use this framework),
I encountered this error:

Suppressed: java.lang.RuntimeException: while resolving method 'toChar[class java.lang.Object]' in class class org.apache.calcite.runtime.SqlFunctions
Caused by: java.lang.NoSuchMethodException: org.apache.calcite.runtime.SqlFunctions.toChar(java.lang.Object)

So I added the required method: org.apache.calcite.runtime.SqlFunctions.toChar(java.lang.Object)

For information, there are already many similar methods for other primitive types (int, bool ...).
So the new toChar(Object) method is similar to those other primitive methods

[mihaibudiu]

Can you also provide a test which fails in the absence of this function?

[pierre-mazieres-semarchy]

@mihaibudiu
There is no Junit class for the SqlFunctions class yet.
I will create one and update this PR.

[mihaibudiu]

No, not unit tests. An end-to-end test is more valuable. Like something with your dummy connector.

[pierre-mazieres-semarchy]

OK, I probably can extract a simple snippet in order to reproduce the issue.

But how should I send it to you ?
In a dummy Java class with a main function ?

[mihaibudiu]

Do write a junit test, but not a unit test for toChar.
You will have to figure out where the test belongs, though (which of the many test files).
I have never used connectors in my code, so I am not sure where they should be tested.

[mihaibudiu]

If you can post here a failing snippet I can perhaps try to look around the codebase to see where similar stuff is tested.

[pierre-mazieres-semarchy]

I added a snippet.

In order to reproduce the original issue:

• Comment the new toChar(Object) method
• In the PrimitiveTest class, run the testUpdate method

The bug is triggered in:

• the PrimitiveTest.testUpdate method on line 37 when running the UPDATE statement: statement.executeUpdate("UPDATE DUMMY.PRIMITIVE SET INT_=1")
• it will call the InMemoryEnumerableTableModify.implement method on line 74 when i=1: childPhysType.fieldReference(o_, i, javaFieldType)
• and then try to call the toChar(Object) method

If you uncomment the toChar(Object) method,
There will be no issue, and the UPDATE statement will be effective.

[mihaibudiu]

Sorry, busy with many reviews for the 1.37 release, didn't have time to properly look at this.
Hope to get back to it soon.

[pierre-mazieres-semarchy]

Hello @mihaibudiu
No problem, take your time.
It is not a big deal on my side,
I made a quick & dirty workaround on my dummy project.
Apache Calcite is not my main project,
so I also can not work on it on full time :D

[mihaibudiu]

I have tried to create a smaller reproduction and I failed.
I guess we could accept this change without a test...
Or a very involved one, like the one you wrote.
I am inclined to suggest for you to just submit a PR with the new toChar function.