Django render many to many attributes after query, display None - django

Question

I am using slug to query the model, and render result in HTML.
The code is unable to render actual name of region, it just return None
Model
class Region(models.Model):
name = models.CharField(blank=False, unique=True)
def __str__(self):
return self.name
class Theme(models.Model):
name = models.CharField(blank=False, unique=True)
slug = models.SlugField(default="", null=False)
def __str__(self):
return self.name
class ETF(models.Model):
ticker = models.CharField(max_length=6, blank=False, db_index=True, unique=True)
full_name = models.CharField(max_length=200, blank=False)
# many to many
region = models.ManyToManyField(Region)
theme = models.ManyToManyField(Theme)
views.py
def theme_etf(request, slug): # render ETFs with theme filter
filtered_results = ETF.objects.filter(theme__slug=slug)
return render(request, "etf/list_etf.html", {
"ETFs": filtered_results
})
Part of list_etf.html
{% for ETF in ETFs %}
<tr>
<td>{{ ETF.ticker }}</td>
<td>{{ ETF.full_name }}</td>
<td>{{ ETF.region.name }}</td> # What should I use in this line
</tr>
{% endfor %}
The code is unable to render actual name of region, it just return None
Result
Ticker, Name, Region
ARKF, ARK Fintech Innovation ETF, None
ARKK, ARK Innovation ETF, None
KEJI, Global X China Innovation, None
I would like to have this:
Ticker, Name, Region
ARKF, ARK Fintech Innovation ETF, Global
ARKK, ARK Innovation ETF, Global
KEJI, Global X China Innovation, China
I have the information in the database. I have checked it in admin.

Answer 1

Can an ETF have multiple regions as implied by your database design? If it does not I would suggest you use ForeignKey instead.
You are accessing the region field as if it were a ForeignKey.
In your database design you need to iterate over the objects saved in the ManyToManyField using .all.
{% for ETF in ETFs %}
<tr>
<td>{{ ETF.ticker }}</td>
<td>{{ ETF.full_name }}</td>
<td>{% for region in ETF.region.all %}{{ region.name }}{%endfor%}</td>
</tr>
{% endfor %}

Answer 2

Because you have many-to-many relationship, you cannot simply have single values. So, you have to list values.
{% for ETF in ETFs %}
<tr>
<td>{{ ETF.ticker }}</td>
<td>{{ ETF.full_name }}</td>
<td>
<ol>
{% for region in ETF.region %}
<li>{{region.name}}</li>
{% endfor %}
</ol>
</td>
</tr>
{% endfor %}