Twig merge multiple things in an array

Question

I'm trying to create an array with dates in it for an order system. Those dates corresponds with days that the shop can't deliver.

I'm having trouble to create that array since values are strings and that keeps getting producing an error with the merge filter. I have only access to the frontend of the shop so I can't create custom functions whatsover.

The end result need to be an array with all dates in it so I can use that as javascript array, like so:

var closed = [
  {{ closedDates }} // ["01-01-2018", "02-01-2018", etc...]      
];

So what I have is this:

1) Webshop fills in the single days they are closed and perhaps a range of days. That are three variables like:

 {{ closedDays }} {# produces eg 01-01-2018, 02-01-2018, 03-01-2018 { it's dd-mm-yy #} 
 {{ date_range_start }} {# produces eg. 10-01-2018 #}
 {{ date_range_end }} {# produces eg. 20-01-2018 #}

2) So what I did is this:

 {% set closedDates = [] %}    


  {% if theme.closedDays %}
    {% set foo = theme.closedDays %}
    {% for i in foo | slice(0, 5) %}
       {% set closedDates = closedDates | merge(i) %}
    {% endfor %}

  {% endif %}

  {% if theme.date_range_start and theme.date_range_end  %}
     {% set start_date = theme.date_range_start  %}
     {% set end_date = theme.date_range_end %}

     {# below function lists all days between start and end date #}
     {% for weekRange in range(start_date|date('U'), end_date|date('U'), 86400 ) %}
        {% set closedDates = closedDates | merge(weekRange | date('d-m-Y')) %} 
     {% endfor %}
  {% endif %}

When I do it like above I get an error saying The merge filter only works with arrays or hashes;. But how do you create an array then with those values? That's only done with merge right?!

Any help greatly appreciated.

Solution

In Twig you can't just push elements to an array. Instead, you have to merge array with another array.

Given one array:

{% set firstArray = ['a', 'b'] %}

if you want to add element 'c', you have to merge it providing an array, even if you want to add single string element.

{% set firstArray = firstArray | merge(['c']) %}

---

If you work with associative arrays, it's analogical:

{% set secondArray = {'a': 'string a', 'b': 'string b' } %}
{% set secondArray = secondArray | merge({'b': 'overwritten!', 'c': 'string c' }) %}

The only diference is that element b will be overwritten with the value from the secondArray, so you'll get:

{
   'a': 'string a',
   'b': 'overwritten!',
   'c': 'string c'
}

Comments

[Meules]

Ok that's something I understand. However isn't that what I tried? Can you perhaps give an exam-ple based on my code?

[entio]

Well @Meules, doesn't my answer contain some examples? I gave you an answer (with examples) which is likely to solve your error. You just want me to implement it for you in a scatter of your code, don't you? :)

[Meules]

Well not exactly :) I don't understand why my code does not work. I do the same like you. Only thing is that closedDays array is empty by default. But you mean I should create an array for weekRange and i and then merge that with closedDays?

[entio]

@Meules I'd really love to help you but have troubles understanding your issue. Naming in your pieces of code is not consistent. In your previous comment you refer to closedDays. Which one? Try this: {% set closedDates = closedDates | merge([weekRange | date('d-m-Y')]) %} PS: groetjes uit Breda :)

[Meules]

Well more or less.... Anyway your example made me clear that I forgot all brackets in the merge filter :( Secondly it helped a lot so I will accept it as answer!

[entio]

@Meules cool! Happy to hear! And curious as well... so what was the issue (besides brackets) after all?

[Vishal Kumar Sahu]

What about using + instead of merge?

[entio]

@VishalKumarSahu + is a Math operator in twig. I believe you can not use it to merge arrays.

[Vishal Kumar Sahu]

I have used + to join/merge like list in python and array in PHP. But for it's usage you need to find out where will it fail.

[entio]

Or you can just read documentation? At least before giving hints ;-)