[jifty-devel] Clauses are AND'd by default in the limit method?
Jesse Vincent
jesse at bestpractical.com
Tue Dec 5 17:07:34 EST 2006
On Dec 5, 2006, at 2:40 PM, Ruslan Zakirov wrote:
> On 12/5/06, Jesse Vincent <jesse at bestpractical.com> wrote:
>>
>>
>>
>> On Tue, Dec 05, 2006 at 04:01:04PM +0800, Agent Zhang wrote:
>> > Hi,
>> >
>> > The Jifty::Manual::Models document contains the following snippet:
>> >
>> > # combining restrictions with "AND"
>> > # note that "AND" is implicit here
>> > $collection->limit(column=>'col1', value=>'...');
>> > $collection->limit(column=>'col2', value=>'...');
>> >
>> > While testing my Qooqle app in Jifty, however, I found "OR" is
>> > implicit here instead. By further examining the source of
>> > Jifty::DBI::Collection, I've seen the following lines:
>>
>>
>> Here's the way it works:
>>
>>
>> * Toplevel clauses default to AND
>> * Subclauses default to OR (though at one point, they defaulted to
>> whatever made sense. You can make decent guesses about what the
>> user
>> means...except that you're often wrong);
>> * By default, each column gets its own subclauses.
>>
>> So:
>>
>>
>> $collection->limit(column => 'col1', value => 'x');
>> $collection->limit(column => 'col1', value => 'y');
>>
>> Will generate :
>>
>> WHERE ( col1 = 'x' OR col2 = 'y');
> WHERE ( col1 = 'x' AND col2 = 'y');
>
How so? My reading of sub limit says this:
sub limit {
my $self = shift;
my %args = (
...
entry_aggregator => 'or',
...
@_ # get the real argumentlist
);
>>
>>
>> $collection->limit(column => 'col1', value => 'x');
>> $collection->limit(column => 'col2', value => 'y');
>>
>> Will generate:
>>
>> WHERE ( col1 = 'x' ) AND ( col2 = 'y');
>>
>> $collection->limit(column => 'col1', value => 'x');
>> $collection->limit(column => 'col2', value => 'x');
>> $collection->limit(column => 'col2', value => 'y');
>>
>> Will generate:
>>
>> WHERE ( col1 = 'x' ) AND ( col2 = 'x' OR col2 = 'y');
>>
>>
>>
>> You can get tricky by playing with the entry aggregator yourself:
>>
>> $collection->limit(column => 'col1', value => 'x');
>> $collection->limit(column => 'col2', value => 'x',
>> entry_aggregator => 'AND');
>> $collection->limit(column => 'col2', value => 'y',
>> entry_aggregator => 'AND');
>>
>> Will generate:
>>
>> WHERE ( col1 = 'x' ) AND ( col2 = 'x' OR col2 = 'y');
> WHERE ( col1 = 'x' ) AND ( col2 = 'x' AND col2 = 'y');
Thanks. Nice catch.
More information about the jifty-devel
mailing list