Display entries with matching checkbox field values

Question

I apologize if this question has been asked before. I'm new at this and am struggling to figure out if what I need to do is possible/the right way to do it or if I need to structure my content differently.

My entries in a section have a field that use a checkbox field type. I would like to display entries that have a matching value based on that field.

Example: Field: Vitamins,

  Field Type: Checkboxes
              Option: Vitamin A  | Value: a
              Option: Vitamin B  | Value: b
              Option: Vitamin C  | Value: c

Section: Vegetables

 -Entry: Broccoli
       Vitamins Field Values: a, c

 -Entry: Corn
       Vitamins Field Values: a, b

 -Entry: Squash
       Vitamins Field Values: a, b, c

I'm trying to figure out how to display all entries that contain Vitamin A.

Answer 1

After I posted my question I ended up coming with something that works:

 {% for entry in craft.entries.section('Vegetables') if entry.Vitamins.contains('a') %}
      <p><a href="{{ entry.url }}">{{ entry.title }}</a></p>
 {% endfor %}

Answer 2

I posted a similar question the other week, I managed to figure it out and I posted my code. Hope it helps:

Filter based Search Form

Answer 3

While the approach above works this is how you'd construct a string to use with craft.entries.search() when you have multiple checkbox fields. The benefit is being able to order entries by relevancy/score.

{% set string = '' %}

{% if craft.request.getParam('outcomes') | length %}
    {% for outcome in craft.request.getParam('outcomes') %}
        {% set string = string ~ ' outcomes:' ~ outcome %}
    {% endfor %}
{% endif %}

{% if craft.request.getParam('age') | length %}
    {% for age in craft.request.getParam('age') %}
        {% set string = string ~ ' age:' ~ age %}
    {% endfor %}
{% endif %}

{% if string != '' %}
    {% set entries = craft.entries.section('interventions').search(string).order('score') %}
{% endif %}