Variable variables in Twig - twig

Question

I'm trying to write a menu with 1 level submenu using hash in Twig. My code is:
{% set regiones = {
patagonia: { title: "Patagonia"},
pampa: { title: "Pampa"},
cuyo: { title: "Cuyo"},
noreste: { title: "Noreste"},
noroeste: { title: "Noroeste"}
} %}
{% set patagonia = {
neuquen: { title: "Neuquén"},
rionegro: { title: "Río Negro"},
chubut: { title: "Chubut"},
santacruz: { title: "Santa Cruz"},
tierradelfuego: { title: "Tierra del Fuego"}
} %}
{% set pampa = {
buenosaires: { title: "Buenos Aires"},
cordoba: { title: "Córdoba"},
lapampa: { title: "La Pampa"},
santafe: { title: "Santa Fe"}
} %}
{% set cuyo = {
mendoza: { title: "Mendoza"},
sanjuan: { title: "San Juan"},
sanluis: { title: "San Luis"}
} %}
<nav>
<ul>
{% for slug, item in regiones %}
<li>{{ item.title }}
<ul>
{% for slugg, itemm in {{ slug }} %}
<li>{{ itemm.title }}</li>
{% endfor %}
</ul>
</li>
{% endfor %}
</ul>
</nav>
This line: " {% for slugg, itemm in {{ slug }} %} " don't work.
How I can write in twig a variable variable like ${$slug} in PHP?
Thanks,
Mikel

Answer 1

_context holds the variables in the current context, so you can do:
{% for slugg, itemm in _context[slug] %}
Because you have not set variables noreste and noroeste, you need to surround the for block with an if block (otherwise Twig will throw an exception as _context doesn't have the keys noreste and noroeste):
{% if _context[slug] is defined %}
<ul>
{% for slugg, itemm in _context[slug] %}
<li>{{ itemm.title }}</li>
{% endfor %}
</ul>
{% endif %}
See TwiggFiddle
An alternative approach is to set the cities to a new hash like this:
{% set cities = {
patagonia: {
neuquen: { title: "Neuquén"},
rionegro: { title: "Río Negro"},
chubut: { title: "Chubut"},
santacruz: { title: "Santa Cruz"},
tierradelfuego: { title: "Tierra del Fuego"}
},
pampa: {
buenosaires: { title: "Buenos Aires"},
cordoba: { title: "Córdoba"},
lapampa: { title: "La Pampa"},
santafe: { title: "Santa Fe"}
},
cuyo: {
mendoza: { title: "Mendoza"},
sanjuan: { title: "San Juan"},
sanluis: { title: "San Luis"}
}
} %}
And then modify your loop like this:
{% if cities[slug] is defined %}
<ul>
{% for slugg, itemm in cities[slug] %}
<li>{{ itemm.title }}</li>
{% endfor %}
</ul>
{% endif %}
And one more approach is to put regions and cities in the same hash:
{% set regiones = {
patagonia: {
title: "Patagonia",
cities: {
neuquen: { title: "Neuquén"},
rionegro: { title: "Río Negro"},
chubut: { title: "Chubut"},
santacruz: { title: "Santa Cruz"},
tierradelfuego: { title: "Tierra del Fuego"},
},
},
pampa: {
title: "Pampa",
cities: {
buenosaires: { title: "Buenos Aires"},
cordoba: { title: "Córdoba"},
lapampa: { title: "La Pampa"},
santafe: { title: "Santa Fe"},
},
},
cuyo: {
title: "Cuyo",
cities: {
mendoza: { title: "Mendoza"},
sanjuan: { title: "San Juan"},
sanluis: { title: "San Luis"},
},
},
noreste: {
title: "Noreste",
},
noroeste: {
title: "Noroeste",
},
} %}
<nav>
<ul>
{% for slug, item in regiones %}
<li>
{{ item.title }}
{% if item.cities is defined %}
<ul>
{% for slugg, itemm in item.cities %}
<li>{{ itemm.title }}</li>
{% endfor %}
</ul>
{% endif %}
</li>
{% endfor %}
</ul>
</nav>