[dancer-users] Trouble with DBIC in Plugins

Matthew Mallard matt at Q-technologies.com.au
Sat May 2 12:34:21 BST 2015


Thanks again for your help.  This code works:
my $schema;

on_plugin_import {
    my $dsl = shift;
    # Grab a handle to the Plugin::DBIC schema
    die "No schema method in app. Did you load DBIC::Plugin::DBIC before Custom::Plugin?" unless $dsl->can('schema');
    $schema = $dsl->schema;
    $dsl->debug( "**** Got Schema **** ");

Having said that, I realise the original code would have worked too but too many things were changing at the same time and it caught me out.  I moved from mysql to postgresql and the case sensitivity was causing a problem, there were rather radical changes in the way Dancer2 was requiring me to structure my code and to top it off the "DEPRECATED: Custom::Plugin calls 'dsl' instead of '$dsl->dsl'. at /perf/perl/lib/perl5/Dancer2/Plugin/DBIC.pm line 13.” was making me think I was on the wrong track.  But this warning remains even with the new code.

Turning statement logging on in postgres helped me track down the case mismatch.


On 2 May 2015, at 7:47 pm, Andrew Beverley <andy at andybev.com> wrote:

> On Sat, 2015-05-02 at 12:50 +1000, Matthew Mallard wrote:
>>>> I’m getting a bit confused with plugins.  I’m sure that I was able to
>>>> use the DBIC Plugin at one point from one of my plugins, but I can’t
>>>> seem to get it to  work in 0.159002 or 0.160000.  DBIC seems to be
>>>> okay outside of plugins.
>>> Firstly, there is change going on in the world of plugins, which I
>>> suspect will fix this, but I haven't read up on the full details myself:
>>> http://lists.preshweb.co.uk/pipermail/dancer-users/2015-April/004512.html
>>>> * how do I get DBIC to print the SQL it’s executing so I can double
>>>> check it’s what I’m expecting?
>>>> * am I doing something else wrong in the way I’m trying to use DBIC?
>>> This is a bit more tricky. With the current plugin architecture,
>>> "schema" is not available in the DSL when you call it from another
>>> plugin as you are doing. You can workaround this by capturing it during
>>> plugin initialisation, as long as you load the DBIC plugin before yours.
>>> See Plugin::Auth::Extensible::Provider::DBIC for an example:
>> So do I create a sub in my custom plugin along these lines:
>> sub new {
>>    my ($class, $dsl) = @_;
>>    # Grab a handle to the Plugin::DBIC schema
>>    die "No schema method in app. Did you load DBIC::Plugin::DBIC before My::Custom::Module?"
>>        unless $dsl->can('schema');
>>    my $schema = $dsl->schema;
> Yes, similar to that, but using on_plugin_import. See this example:
> https://github.com/PerlDancer/Dancer2-Plugin-Auth-Extensible/blob/de84a4a5baf5b56a83906355de075678c485fc51/lib/Dancer2/Plugin/Auth/Extensible.pm#L1158
>>    my $self = {
>>        dsl_local      => $dsl,
>>        schema         => $schema,
>>    };
>>    return bless $self => $class;
> I don't think you need to bless your class, as it's already blessed. You
> just need to store the schema in a global in your module, a bit like
> $settings here:
> https://github.com/PerlDancer/Dancer2-Plugin-Auth-Extensible/blob/de84a4a5baf5b56a83906355de075678c485fc51/lib/Dancer2/Plugin/Auth/Extensible.pm#L13
>> Then in my routes module I call plugins in this order:
>> use Dancer2::Plugin::DBIC
>> use My::Custom::Module
> Yes.
>> How does 'new' get called and what do I use to reference the schema in my custom plugin.
> See above.
>> Let me know if there is some other background reading I should be doing
>> for how this work,
> To be honest, it's a dirty hack, so you won't find any documentation on
> it. You might be better waiting for the new plugin architecture if you
> can.
> Andy
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