Craft 2.x - Filtering entries in a single Twig template

craft-template-with-querystring-filters.twig

{# How to handle querystring filters in a single Twig template. #}

{# Baseline entries/categories criteria. #}
{# Set any criteria here that will be relevant regardless of filters. #}
{# Section name can be array if you need to fetch from more than one section. #}
{% set criteria = {
    section: ['sectionName'],
    order: 'postDate desc',
    limit: 9
} %}

{# Check for any existing filters in the querystring. #}
{% set filters = {} %}
{# Populate with all querystring parameter to look for. #}
{% set querystringParams = ['t', 'c'] %}
{# Loop through querystring params. #}
{% for param in querystringParams %}
    {# If querystring param is in the URL, merge into the filters object. #}
    {% if craft.request.getParam(param) %}
        {% set filters = filters|merge({
            (param): craft.request.getParam(param)
        }) %}
    {% endif %}
{% endfor %}

{# Are we filtering? #}
{% if filters|length %}
    {# Use 'and' if you want to require all relations. User 'or' to match any relation. #}
    {% set relations = ['and'] %}
    {# Loop through the filters and populate the relations. #}
    {% for key, value in filters %}
        {# Need to pass an entry ID as the `relatedTo` value. #}

        {# ID as querystring value. #}
        {# If using the entry ID as the querystring value, just set the id to the value. #}
        {% set id = value %}

        {# --------- #}

        {# Slug as querystring value. #}
        {# If using the entry slug as the querystring value, need to fetch the entry/category ID first. #}
        {# {% set entry = craft.entries.section('sectionHandle').slug(value).first() %} #}
        {# Make sure we actually have an entry, accounts for cases where the querystring may have been manipulated. #}
        {#{% if entry|length %}#}
            {#{% set id = entry.id %}#}
        {#{% endif %}#}

        {# --------- #}

        {# Make sure we have an entry ID. #}
        {% if id is defined and id|length %}
            {% set relations = relations|merge([
                { targetElement: id }
            ]) %}
        {% endif %}
    {% endfor %}
{% endif %}

{# Merge in relations if we have any. #}
{% if relations is defined and relations|length %}
    {% set criteria = criteria|merge({
        relatedTo: relations
    }) %}
{% endif %}

{# Finally, fetch the entries. #}
{% set entries = craft.entries(criteria) %}

<p>Criteria:</p>
<pre>{{ dump(criteria) }}</pre>