I have an array of hashes:
a = [{a:"ahmed", b: "gaber"}, {a: "biga", b: "gaber"}]
I want to map the array into a comma separated string with each separated part being the concatenation of the values of a hash. In ruby, this would be written:
a.map {|o| o[:a] + o[:b] }.join(",")
How can I write this in Liquid?
If you're writing directly to the output, you could use a for tag, e.g.:
{% for item in items %}{% if forloop.first == false %},{% endif %}{{ item.a }} {{ item.b }}{% endfor %}
==> "ahmed gaber,biga gaber"
But if you're trying to assign to a variable, I don't think there's a way to do that purely in liquid because there's no filter that is the equivalent to the ruby map function. The closest I can think of is to preprocess the list so it looks like this:
a = [{a:"ahmed", b: "gaber", c: "ahmed gaber"},
{a: "biga", b: "gaber", c: "biga gaber"}]
and then use liquid map to pluck the "c" field from each hash:
{{ assign csv = items | map: "c" | join: ","}}
The result is: {{ csv }}
==> "ahmed gaber,biga gaber"
Liquid has a map filter for arrays, but it only lets you access one attribute from each object in your array: https://docs.shopify.com/themes/liquid-documentation/filters/array-filters#map
There is a pretty thorough answer on iterating through hashes in Liquid here: Iterate over hashes in liquid templates
Using the above answer as a template, you could iterate (and present) your data in the way you specified with these tags:
{% for name in a %}
{{ name.a }} {{ name.b }}{% unless forloop.last %},{% endunless %}
{% endfor %}
One other piece to this markup is the use of the forloop variable from inside the loop. With this we can place a comma unless we're at the last entry in the array.
More on liquid forloops (and pretty much everything else liquid) here: https://github.com/Shopify/liquid/wiki/Liquid-for-Designers
