Determine Entry based on URL Parameters?

Question

I have a bit of code that checks if a page's title has been manually set in a parent template, and if it has to use that, otherwise to use entry.title. This is what that bit looks like:

{% set activeTitle %}
     {% if pageTitle is defined %}
         {{ pageTitle }}
     {% else %}
         {{ entry.title }}
     {% endif %}
{% endset %}

I however have some pages like so:
http://example.com/foo/text.html?sectionId=6&handle=bar&entryId=170&slug=somethingclever

How do I get the entry based on the parameters that are defined in the URL? And then use this entry's entry.title to set my page title?

Answer 1

This is a longer version answer (code wise) to the one Douglas already posted. He did a very nice job of explaining how to get a URL parameter and what to pay attention to handling the results.

I will try to show you how to build a query from multiple unknown params, so any of these combinations is possible and potentially return a single (and unique) Entry Model:

http://example.com/foo?sectionId=6&entryId=170&slug=somethingclever
http://example.com/foo?sectionId=6&slug=somethingclever
http://example.com/foo?entryId=170

This also tries to handle the case, the page already comes with an entry variable pre-populated or there's already a pageTitle set. So you don't do all the requests / logic on all of your pages.

{#
 # Only try parsing the params, if this page doesn't come with an `entry`
 # var pre-populated and we don't already have `pageTitle` set.
 #}
{% if not entry and pageTitle is not defined %}

    {# Get URL params #}
    {% set entryId = craft.request.getParam('entryId') %}
    {% set entrySlug = craft.request.getParam('slug') %}
    {% set sectionId = craft.request.getParam('sectionId') %}

    {# Default query #}
    {% set query = craft.entries %}

    {# Add params to the query if they are not empty #}
    {% set query = not entryId ? query : query.id(entryId) %}
    {% set query = not entrySlug ? query : query.slug(entrySlug) %}
    {% set query = not sectionId ? query : query.sectionId(sectionId) %}

    {# Now try to get that entry and set our own `entry` var #}
    {% set entry = query.first() %}

{% endif %}

{# Set the entry title. Also handle the case our query didn't find anything #}
{% set entryTitle = entry ? entry.title : 'Title for a page that doesn’t exist' %}

{# Set the page's title #}
{% set activeTitle = pageTitle is defined ? pageTitle : entryTitle %}

Useful links for this code: craft.request and Ternary operator in Twig.

Answer 2

You can access 'post' or 'get' parameters using craft.request.getParam('param'); and then use them to retrieve the corresponding entry. So, given the URL:

http://example.com/subsection/filename.html?id="170"

In your template, you would grab the param 'id', and use it to retrieve the entry.

{% set entryId = craft.request.getParam('id') %}
{% set entry = craft.entries.id(entryId).first() %}
{% if entry %}
    {% set pageTitle = entry.title %}
{% endif %}

Notice the use of .first(). Results from craft.entries are returned as an ElementCriteriaModel, which is an 'array-like' object, even if only one 'entry' is defined — .first() returns the first element. To avoid errors if no entries are found matching the criteria, check that 'entry' exists before trying to access its properties.

Likewise, do not try and loop through an entry retrieved using .first(), which will also throw an error.