[Dbix-class] DBIx and Arbitrary SQL through a custom ResultSource

[Vangelis Katsikaros]

Hi Peter

On 01/21/2012 03:27 PM, Peter Rabbitson wrote:
> Vangelis Katsikaros wrote:
>> Hello
>>
>> I had a problem following the instructions in "Arbitrary SQL through a
>> custom ResultSource" [1] since it gave me an error of `Can't locate
>> object method "result_source_instance"`
>>
>> I found a solution in this perlmonk answer [2]. Indeed this works:
>>
>> <code>---------------------------
>>
>> package Dir::Dir::ComplexQuery;
>>
>> use strict;
>> use base 'DBIx::Class::Core';
>>
>> __PACKAGE__->table( 'dummy_table_name' );
>> __PACKAGE__->add_columns( qw/col1 col2 col3/ );
>> __PACKAGE__->result_source_instance->name( \q!(complex SQL ... )! );
>>
>> </code>---------------------------
>>
>> and I can normally do:
>> ...->resultset('ComplexQuery')->search();
>>
>> My questions are the following:
>>
>> 1. The function "table" is the one from
>> DBIx::Class::ResultSourceProxy::Table as described in [3], right? I am
>> using `DBIx::Class::Schema::Loader` so I never had created a DBIx
>> "class table" myself.
>
> Yes. What you witnessed is a side effect of a long standing wart.
> This will be solved in the next release or two (bogus ->table calls
> will no longer be needed). I could explain why this is currently
> necessary, but I rather not since 1) this code is not for the faint
> of heart and 2) it is entirely going away. I will however elaborate
> more if you express further interest.

Thanks for offering to explain in depth, but I think there is no need to 
elaborate on this - your arguments are clear. Use this time more 
productively :)


>> 2. The "__PACKAGE__->table('table_name')" will NOT trigger a creation
>> of this table (in this case it's a view) to the actual DB, correct?
>> Or is there a scenario where the creation of a view hac be triggered
>> and I can end up with a view named 'dummy_table_name' in my DB?
>
> Creation is not something that ever happens automatically in DBIC.
> Such a table definition *may* be included in a subsequent call to
> deploy(), unless you follow the new improved way of doing things to
> which Wolfgang already pointed you.
>
>> 3. In which DBIx package is "result_source_instance" defined? I did
>> searched but I couldn't find it - maybe I am not searching the right way.
>>
>
> See the answer to point 1, in particular this is one of the "not for
> the faint of heart" references (the method is created at runtime, per
> class, depending on certain conditions).
>


Thanks for all the answers,
Vangelis