On Wednesday, January 8, 2020 at 9:33:55 AM UTC-8, BeeRich33 wrote:
>
>
>> My apologies for correcting you yet again, hence the questions here in
> the group meant for such questions:
>
> DBS[:searches_t].
> where{(exclude(search_phrase: nil))}.
> select(:search_phrase, :result_count)
>
>
> ERROR. *HINT: No function matches the given name and argument types.
> You might need to add explicit type casts. *Points to "exclude"
>
> The "Where TRUE" is what the .sql is explaining. From here:
>
> where{(exclude(:search_phrase = nil) & (:client_ip != '192.168.1.4')}.
>
>
This doesn't work for multiple reasons. I don't even think it is valid
ruby syntax (:search_phrase = nil). Even if you fixed the Ruby syntax
issues, you don't want to call exclude inside where, as it isn't an SQL
function, and :client_ip != '192.168.1.4' is always going to be true, since
a Ruby symbol is not ever equal to a Ruby string.
> Question still not answered. I've simplified the query to the following,
> which still has no answer:
>
> DBS[:searches_t].
> where{(exclude(search_phrase: nil))}.
> select(:search_phrase, :result_count)
>
Here you are using the virtual row syntax to call the exclude SQL function,
except that exclude is not an SQL function. You want to call
exclude(search_phrase: nil) instead of where{(exclude(search_phrase: nil)
I've also tried:
> DBS[:searches_t].
> where{(:search_phrase != nil)}.
> select(:search_phrase, :result_count)
>
> => provides nils. So that doesn't work.
>
A Ruby symbol will never equal nil. You could possibly use
where{search_phrase !~ nil}, though the exclude example given above is more
idiomatic.
>
> I've also tried:
>
> DBS[:searches_t].
> where{(:search_phrase !~ nil)}.
> select(:search_phrase, :result_count)
>
> => provides nils. Doesn't work.
>
Sequel doesn't override Symbol#!~ (or any core Ruby methods by default).
(:search_phrase
!~ nil) returns true, so the where call is the same as where{true}
> I'm reading as much as I can, and wish to avoid coming in here. Believe
> me.
>
While the documentation covers the issues you have brought up, it does not
directly address your particular use case. The documentation does assume
an intermediate level understanding of the Ruby language, so it doesn't
directly explain why only one of the following gives you the results that
you want:
where{:search_phrase != nil}
where{:search_phrase !~ nil}
where{search_phrase != nil}
where{search_phrase !~ nil}
In short, :search_phrase and search_phrase are different here, with
:search_phrase being a Ruby symbol and search_phrase being a method call
that returns a Sequel-specific object. That object implements !~ but not
!=, as overriding != would break Ruby-level equality.
You should be aware that this is a help forum for the Sequel library, not a
forum to help you with your specific project. You should try to keep your
requests for help generic (unrelated to your project), and as minimal as
possible for the topic you have a question about. It would probably be
best if you could always post the SQL you are trying to generate, and ask
how to represent it in Sequel, as that minimizes the potential problems.
Thanks,
Jeremy
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