Return errors in QueryRow properly

[codemac]

• oracle.go: Handle QueryRow multiple return values
• postgres.go: Handle QueryRow multiple return values
• qbs.go: Return an error during QueryRow

This fixes a panic in the qbs.Count and qbs.ContainsValue implementation

Signed-off-by: Jeff Mickey [email protected]

[codemac]

See #54 for details of why this is necessary.

[coocood]

Thank you for reporting the panic issue, but I can not merge this PR because it is an API change, ti will break the previous working code.

Can we just check if the row is nil and return 0 in the "Count" method?

[codemac]

Well, you certainly could, but I think the other function (doQueryRow, doQueryRows) all return errors as well, so this seems like a natural implementation. You don't document what QueryRow will return on error, and I think maintaining hidden behavior is a bad choice. Semantic change requiring two different code changes (an if row == nil or if err != nil) means you're changing the API either way.

You're more than welcome to make changes to your code however you wish, this took me very little time to fix.

[coocood]

I just remembered that I didn't return error in "QueryRow" method because I follow the standard library "database.sql" package . So the error shoud be set in the "Row", and the "Row" should never be nil.

Would you please change it this way, then I will merge it as soon as possible.

Thank you.

[codemac]

On February 9, 2015 8:05:37 PM PST, Ewan Chou [email protected] wrote:

I just remembered that I didn't return error in "QueryRow" method because I follow the standard library "database.sql" package . So the error shoud be set in the "Row", and the "Row" should never be nil.

Would you please change it this way, then I will merge it as soon as possible.

Thank you.

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Reply to this email directly or view it on GitHub: https://github.com/coocood/qbs/pull/55#issuecomment-73641128

Ahhh that makes much more sense now that you explain it. Will change it accordingly. // mickey

[codemac]

Problem - the err in sql.Row is unexported. I don't know how to set the error in Row. As long as a tx.Prepare is tied up in this API, I don't think it's possible without our own Row type.

[coocood]

We can set the error via reflection.

[codemac]

It's unexported, you can't reflect on it... which struct are you talking about reflecting on? sql.Row.err is private to the stdlib. I think I'm misunderstanding the issue.

[coocood]

Sorry, I didn't write go reflection for a whiel and confused it with JAVA reflection.

Then if we failed to prepare, we can just call db.QueryRow,, if tx is not nil, we call tx.QueryRow.