# Saving API data and call it in views

**URL:** <https://forum.djangoproject.com/t/saving-api-data-and-call-it-in-views/4916>\
**Category:** Using Django\
**Created:** [October 22, 2020, 3:02pm UTC](https://forum.djangoproject.com/t/saving-api-data-and-call-it-in-views/4916 "2020-10-22T15:02:04Z")\
**Posts on this page:** 7\
**Page:** 1

<div class="post-metadata">

**Author:** ![IFarhat](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/ifarhat/32/2283_2.png) [@IFarhat](https://forum.djangoproject.com/u/IFarhat)\
**Post date:** [October 22, 2020, 3:02pm UTC](https://forum.djangoproject.com/t/saving-api-data-and-call-it-in-views/4916/1 "2020-10-22T15:02:04Z")

</div>

Hi there,

I have written the following: basic idea would be for the macro\_char() in views.py to consumer an API, save the data to a model called Macro and from the model spit out the data within the context. Getting the following error message when the template is rendered, "local variable ‘data’ referenced before assignment

Would be great if folks could help out, please, cheers. Ismail

```auto
def macro_chart(request):
   try:
   	url = 'https://api.db.nomics.world/v22/series/BOE/3687/IUAAAJNB?observations=1'
   	response = requests.get(url)
   	response_json = json.loads(response.content)
   	time.sleep(0.5)
   	data_attr = {
   		'dataset_name': response_json['series']['docs'][0]['dataset_name'],
   		'periods': response_json['series']['docs'][0]['period'],
   		'dataset': response_json['series']['docs'][0]['value']
   		}
   	data = Macro.objects.create(**data_attr)

   	data.save()
   		
   except Exception as e:
   	response = "Opps something is wrong with the API"

   context = {
   		"periods": data.periods, 
   		"dataset": data.dataset
   	}
   return render(request, "macro_main.html", context)

```

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<div class="post-metadata">

**Author:** ![KenWhitesell](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/kenwhitesell/32/280_2.png) [@KenWhitesell](https://forum.djangoproject.com/u/KenWhitesell)\
**Post date:** [October 22, 2020, 3:06pm UTC](https://forum.djangoproject.com/t/saving-api-data-and-call-it-in-views/4916/2 "2020-10-22T15:06:51Z")

</div>

Just a note for future reference - when you post code here, please enclose it between lines consisting of only three backtick - ` characters. That means you’ll have one line of ```, then your code, then another line of ```. This preserves the formatting of the code making it a lot easier to read - especially with statements where indentation is critical.

example:

````auto
# The line above this is ```
def function(self):
    return self
# The line after this is ```

````

If you can, please edit your post to put the ``` before and after the code.

Ken

---

<div class="post-metadata">

**Author:** ![KenWhitesell](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/kenwhitesell/32/280_2.png) [@KenWhitesell](https://forum.djangoproject.com/u/KenWhitesell)\
**Post date:** [October 22, 2020, 3:11pm UTC](https://forum.djangoproject.com/t/saving-api-data-and-call-it-in-views/4916/3 "2020-10-22T15:11:57Z")

</div>

Cool, ok, so the problem is that the api call failed for whatever reason. This means that your code didn’t execute the `data=...` line, leaving the variable `data` undefined.

After the exception is processed, you then try to build a dict named `context` which is making a reference to `data` - but since it wasn’t assigned, the error is being thrown.

---

<div class="post-metadata">

**Author:** ![IFarhat](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/ifarhat/32/2283_2.png) [@IFarhat](https://forum.djangoproject.com/u/IFarhat)\
**Post date:** [October 22, 2020, 3:17pm UTC](https://forum.djangoproject.com/t/saving-api-data-and-call-it-in-views/4916/4 "2020-10-22T15:17:59Z")

</div>

I assumed because the fields in the Model match the fields in `data_attr=`, then the syntax would work. In models.py I have the following code

```auto
from django.db import models
from datetime import datetime, date

# Create your models here.
class Macro(models.Model):
	dataset_name = models.CharField(max_length=30, blank=True)
	periods = models.DateField(auto_now_add=False, auto_now=False, blank=True)
	dataset = models.DecimalField(max_digits=5, decimal_places=2)

	def __str__ (self):
		return self.dataset_name

```

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<div class="post-metadata">

**Author:** ![KenWhitesell](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/kenwhitesell/32/280_2.png) [@KenWhitesell](https://forum.djangoproject.com/u/KenWhitesell)\
**Post date:** [October 22, 2020, 3:42pm UTC](https://forum.djangoproject.com/t/saving-api-data-and-call-it-in-views/4916/5 "2020-10-22T15:42:45Z")

</div>

The failure could be _anywhere_ within the try block. You’re swallowing the exception and not providing yourself with any debugging information. You’ll get the same symptoms regardless of the actual problem.

---

<div class="post-metadata">

**Author:** ![IFarhat](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/ifarhat/32/2283_2.png) [@IFarhat](https://forum.djangoproject.com/u/IFarhat)\
**Post date:** [October 27, 2020, 1:29pm UTC](https://forum.djangoproject.com/t/saving-api-data-and-call-it-in-views/4916/6 "2020-10-27T13:29:47Z")

</div>

Thanks, Kevin, that really helpful. The issue seems to be the data I’m receiving from the API is time-series data, after parsing the code below, I get list. For example periods would be [‘1976’, ‘1977’, ‘1978’, ‘1979’] and dataset would be [‘5.2’, ‘4.7’, ‘5.6’, ‘1.3’]

```auto
data_attr = {
		'periods': response_json['series']['docs'][0]['period'],
		'dataset': response_json['series']['docs'][0]['value']
		}

```

My model has the following fields, and I suspect it’s not the correct one:

```auto
class Macro(models.Model):
	dataset_name = models.CharField(max_length=30, blank=True)
	periods = models.IntegerField(blank=True, null=True)
	dataset = models.DecimalField(max_digits=5, decimal_places=2)

	def __str__ (self):
		return self.dataset_name

```

What is the best way to store such data in a model, for example, `ArrayField`, or potentially convert the data to Pandas Dataframe and store in the model?

---

<div class="post-metadata">

**Author:** ![KenWhitesell](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/kenwhitesell/32/280_2.png) [@KenWhitesell](https://forum.djangoproject.com/u/KenWhitesell)\
**Post date:** [October 27, 2020, 2:49pm UTC](https://forum.djangoproject.com/t/saving-api-data-and-call-it-in-views/4916/7 "2020-10-27T14:49:06Z")

</div>

This isn’t a case of a choice being “correct” or “incorrect”, it’s extremely context sensitive. I’d say it’s really going to depend upon what you’re going to do with it after you’ve gotten it stored.

In this case, I’d be considering how much data I’m going to have and what queries are going to be run on it. For example, am I just going to be retrieving values by year? Or am I going to want to do something like “Find all years where the value is \> 5”? Am I going to have 10 sets of data like this? Or is it going to be more like 10,000? Or even 10,000,000? (Or more?)

If I don’t have those answers, then I tend to start with a fully-normalized structure, which would be something like (shortened, and written off-the-cuff):

```auto
class DataSet(Model):
    dataset_name = models.CharField(max_length=30, blank=True)
    date_retrieved = models.DateTimeField(...)

class Data(Model):
    dataset = models.ForeignKey(DataSet, ...)
    year = models.IntegerField(...)
    value = models.DecimalField(...)

```

But in the small/trivial cases (\< 1000ish rows) your structure isn’t going to make a whole lot of difference. You could just as easy serialize the entire response and store it in a JSONField without causing you any serious difficulties. I’ve got one table (around 3000 rows) where I’ve done that quite successfully. PostgreSQL effectively keeps the entire row in cache in memory. There’s no visible lag, latency, or delay with performing JSON-based queries on that table compared to a more normalized structure.

Ken