To try to answer my own questions....
Assuming the find returns a single element, the following lines are
equivalent. This seems to show that the Mojo::Collection method call
map('text') calls the Mojo::DOM text method for each element in the
collection -- returning a list (Collection) of the text values of the
elements.
my $item_price = $dom->find('h3[itemprop="price"]')->map('text')->[0];
my $item_price = $dom->find('h3[itemprop="price"]')->[0]->text;
And the following lines are equivalent (sort of). Both return the id
attribute value for the first element returned by the find method call.
The second line would seem to be more efficient when multiple elements are
returned by the find call. This seems to show that map(attr=>"id") calls
the Mojo::DOM attr method (with a parameter value of 'id') for each element
in the collection.
my $item_id1 = $dom->find('div[id*="item-"][class="product"][data-in-
stock="yes"]')->map(attr=>'id')->[0];
my $item_id1 = $dom->find('div[id*="item-"][class="product"][data-in-
stock="yes"]')->[0]->attr('id');
Maybe?
On Sunday, March 20, 2016 at 3:37:16 PM UTC-4, [email protected] wrote:
>
> I'm brand new to Mojolicious (less than a week) and have some hopefully
> simple questions about the Mojo::Collection map and Mojo::DOM attr methods
> (Mojolicious v6.53).
>
> I've seen numerous code examples similar to the following which don't
> *seem* to match the map method signature in the documentation.
>
> my $product_ids =
> $dom->find('div[id*="item-"][class="product"][data-in-stock="yes"]')->map(attr=>'id');
>
> my $item_price = $dom->find('h3[itemprop="price"]')->map('text');
>
>
>
> Both of these map method calls work (produce the intended result) but I'm
> scratching my head how / why they work given the documentation on the
> Mojo::Collection map <http://mojolicious.org/perldoc/Mojo/Collection#map>
> method (and the source too). The first example sure looks like a hash
> element being passed and the second example, a string, neither of which
> appear to be a callback or method reference shown in the documentation.
> Curiously, these map method calls look like the method signatures for the
> Mojo::DOM attr <http://mojolicious.org/perldoc/Mojo/DOM#attr> method.
>
> Instead of the map calls in the above, could / should I be using attr
> method calls? But the result of a $dom->find() call is a Mojo::Collection
> object... and attr is a Mojo::DOM method.
>
> Clearly, I'm missing something fundamental here. Help?
>
>
> And one more newbie question, is there a good reason (e.g., backward
> compatibility with earlier releases) to use the Mojo::Collection to_array
> <http://mojolicious.org/perldoc/Mojo/Collection#to_array> method to
> access an element of a Mojo::Collection?
>
> my $item_price =
> $dom->find('h3[itemprop="price"]')->map('text')->to_array->[0];
>
> versus
>
> my $item_price = $dom->find('h3[itemprop="price"]')->map('text')->[0];
>
>
>
> Thank you.
>
> ... Dewey
>
>
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