[Dancer-users] generating client side code on the server

[franck]

On Sat, Jan 8, 2011 at 1:43 AM, Puneet Kishor <punk.kish at gmail.com> wrote:

> Consider the most basic of workflows
>
>    ## Perl
>    get '/:foo_id.:format' => sub {
>        my $foo_id = params->{foo_id};
>
>        ## SQL
>        my $sth = $dbh->prepare(qq{
>            SELECT foo FROM table WHERE foo_id = ?
>        });
>        $sth->execute($foo_id);
>        my ($foo) = $sth->fetchrow_array;
>
>        to_json({data => $foo});
>    };
>
>
>    foo.tt
>    ======
>    <p>You got <span id="foo">[% foo %]</span></p>
>    enter a number <input type="text" id="foo_id" name="foo_id">
>    <input type="button" onclick="foo();">
>
>    JavaScript
>    ==========
>    foo = function() {
>        $.ajax({
>            url     : "/server/" + $("#foo_id").val() + ".json",
>            type    : "GET",
>            data    : "",
>            dataType: "json",
>            error   : function() { alert("Error"); },
>            success : function(data) {
>                $("#foo").html(data.foo);
>            }
>        });
>    }
>
>
> If I change the table column 'foo' to 'bar' and 'foo_id' to 'bar_id', I
> have to change my Perl code (which includes SQL), my template and
> JavaScript. Obviously, this can get untenable very quickly as the
> application becomes complex. The obvious solution is to generate the
> template and the JavaScript on the server side, thereby having to declare
> all the names in just one place. I have recently learned of the Perl module
> Jemplate that might enable me to do this. But before I commit any cycles to
> it, I want to know how the other Dancers handle something like this.
>

another solution is to use DBIx::Class, where you can declare your schema
with:

__PACKAGE__->add_columns( foo => {name => 'foo'}, ...);

and later change your schema to:

__PACKAGE__->add_columns(foo => {name => 'foo_id'}, ...);

so you don't have to change your code, only your schema.
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