在 Django 模板中渲染空白 ImageFields

Question

I am trying to render an instance of this model in my template:

class Candidate(models.Model):
    UserID = models.ForeignKey(User, on_delete=models.CASCADE)
    ElectionID = models.ForeignKey(Election, on_delete=models.CASCADE)
    Bio = models.CharField(max_length=500, blank=True)
    Poster = models.ImageField(upload_to="profilepics/", null=True, blank=True)

I am having trouble with rendering the Poster attribute which, as you can see, has the option of being blank.

When I try to render the following html in the template:

<h1>{{candidate.UserID.first_name}} {{candidate.UserID.last_name}} ({{candidate.UserID.username}})</h1>
<h2>{{candidate.ElectionID}}</h2>
<img src="{{candidate.Poster.url}}" width=240><br>

I get an error if Poster is blank.

ValueError: The 'Poster' attribute has no file associated with it.

How do I prevent this error? I want to show nothing if Poster is blank and obviously show the image if it isn't.

Answer 1

Use an if condition.

<h1>{{candidate.UserID.first_name}} {{candidate.UserID.last_name}} ({{candidate.UserID.username}})</h1>
<h2>{{candidate.ElectionID}}</h2>
{% if candidate.Poster %}
    <img src="{{candidate.Poster.url}}" width=240>
{% endif %}
<br>