Django: how to transfer scattered data to a template?

Question

Introduction

In Django, when the data you want to display on a template is included in one object, It's f**** easy. To sum up the steps (that everyone knows actually):

1. You Write the right method to get your object in your model class
2. You Call this method in your view, passing the result to the template
3. You Iterate on the result in the template with a for loop, to display your objects in a table, for example.

Now, let's take a more complex situation

• Let's say that the data you want to display is widely spread over different objects of different classes. You need to call many methods to get these data.
• Once you call these different methods, you got different variables (unsimilar objects, integers, list of strings, etc.)
• Nevertheless, you still want to pass everything to a template and display a pretty table in the end.

The problem is:

• If you're passing all the raw objects containing the data you need to your template, it is completely unorganised and you can't iterate on variables in a clean way to get what you need to display your table.

The question is:

How (which structure) and where (models? views?) should I organize my complex data before passing it to a template?

My idea on this (which can be totally wrong):

For each view that need "spread data" to pass to a template, I could create a method (like viewXXX_organize_data()) in views.py, that would take the raws objects and would return a data structure with organized data that would help me to display a table by iterating on it.

About the data structure to choose, I compared lists with dictionaries

• dictionaries have key so it's cleaner to call {{dict.a-key-name}} rather than {{ tabl.3}} in the template.
• lists can be sorted, so when you need to sort by date the elements you want to display, dictionary is not helpful, arghh, stuck again!

What do you think about all that? Thanks for reading until there, and sharing on this!

Answer 1

With your question you are entering in a conceptual/architectural domain rather than in a "this particular view of the data in my project is hard to represent in the template layer of django". So I will try to give you the birds view (when flying and not on the ground) of the problem and you can decide for yourself.

From the first philosophy box in the django template language documentation it's clearly stated that templates should have as little program logic as possible. This indicates that the representation of the data used in the template should be simple and totally adapted to the template you are trying to build (this is my interpretation of it). This approach indicates that you should have a layer responsible for intermediating the representation of your data (models or other sources) and the data that your template needs to achieve the final representation you want you users to see.

This layer can simple stay in your view, in viewXXX_organize_data, or in some other form respecting to a more complex/elaborated architecture (see DCI or Hexagonal).

In your case I would start by doing something like viewXXX_organize_data() where I would use the most appropriate data structures for the template you are trying to build, while keeping some independence from the way you obtain your data (through models other services etc). You can even think of not using you model objects directly in the template and creating template specific objects to represent a certain view of the data.

Hope this helps you make a decision. It's not a concrete answer but will help you for sure make a decision and then staying coherent all trough your app.