On Mon, Dec 14, 2020 at 6:34 AM Rodrigo Rosenfeld Rosas <[email protected]>
wrote:
> Hi, today I've faced something unexpected.
>
> I've changed one library to increment the model's version and in some code
> using the library, I was comparing the version and the expected failed
> wasn't matching.
>
> Then I noticed that when we do:
>
> model.update version: Sequel.lit('version + ')
>
> Then model.version won't reflect the computed version after the update
> statement.
>
> This is unexpected because I'd assume all around that calling
> model.version would always retrieve the actual value of the field. What
> would be the recommended Sequel way to deal with that? Avoid using literal
> when using the update instance method? Are there any refresh-like methods
> that would only refresh a single column (or a set of columns)?
>
Model instances deal only with values, not with SQL expressions, and a
literal string is an SQL expression. To deal with SQL expressions, you
should to drop down to dataset level, and Model#this returns a dataset for
the specific instance:
model.this.update version: Sequel.lit('version + 1')
Currently, Sequel doesn't offer support for refreshing single columns in
model objects. If the database supports UPDATE RETURNING, you could do:
model.values[:version] = model.this.returning(:version).update(version:
Sequel.lit('version + 1'))[0][:version]
Thanks,
Jeremy
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