How to setup conditionals within a matrix?

Question

In my matrix field, I want to be able to upload my image, and then upload another asset (in this case it would be a document) so that that image I upload links to that document.

I have my Matrix field setup like so:

Image -> -Image -linkedDocument

How can I set up a conditional where only add in the tag if I add an asset there?

Here is my relevant code:

% elseif block.type == "image" %}

        {% set image = block.image.first() %}

        {% if image %}
            <a href="{{ image.linkedDocument }}"><img src="{{ image.getUrl('thumb') }}" width="{{ image.getWidth('thumb') }}" height="{{ image.getHeight('thumb') }}" alt="{{ image.title }}"></a>
            {% endif %}
        {% endif %}

Answer 1

If you have an image, you want to display it, and if there is also a linkedDocument, you want the image to link to that document. This should handle both cases, without too much code duplication.

{% if block.type == "image" %}

  {% set image = block.image.first %}

  {% if image %}
    {# set the imgTag, which we will display regardless #}
    {% set imgTag %}
      <img src="{{ image.getUrl('thumb') }}" width="{{ image.getWidth('thumb') }}"  height="{{ image.getHeight('thumb') }}" alt="{{ image.title }}"></a> alt="{{ image.title }}">
    {% endset %}

    {% set linkedDocument = block.linkedDocument.first %}

    {# we may or may not have a linkedDocument. Display the image in either case #}
    {% if linkedDocument %}
      <a href="{{ linkedDocument.url }}">{{imgTag}}</a>
    {% else %}
      {{imgTag}}
    {% endif %}
  {% endif %}

{% endif %}

Answer 2

Very close. It just looks like you are trying to reference the 'linkedDocument' through 'image' instead of through the block, and you are not retrieving the url.

{% if block.type == "image" %}

    {% set image = block.image.first %}
    {% set document = block.linkedDocument.first %}

    {% if image %}
        {% if document %}<a href="{{ document.url }}">{% endif %}<img src="{{ image.getUrl('thumb') }}" width="{{ image.getWidth('thumb') }}" height="{{ image.getHeight('thumb') }}" alt="{{ image.title }}">{% if document %}</a>{% endif %}
    {% endif %}

{% endif %}

Update: Added conditional for if document. Essentially the same answer as Marion's.