TIL/2020–11–12

Today, I learned about Django’s field lookups and using it in conditional filtering.

First let me talk about Django’s field lookups. If you want to take a look at the documentation, it is located in the QuerySet API Reference under “Field lookups”. I used Django’s field lookups using the filter() method where I am trying to filter the QuerySet that I have. My QuerySet contains around 151 rooms/objects that were previously made in my models and were seeded. You can also use Field lookups in get() and exclude() method as well. Today I will talk about how I used it with filter().

There are different ways where you can use field lookups in filter(). You can filter by exact (exact match), contains (as long as it contains the characters), gte (greater than or equal to), lt (less than), lte (less than or equal to) and more.

I am currently working on an Airbnb Clone project and to use Django’s field lookups, I used conditional filtering to be able to get the values from my rooms QuerySet.

This is from my models.py in my rooms application. To give you some context to where I am getting my values and why I am using city, country, room_type, etc. is because I am getting these and filtering these from my Room Model QuerySet. That is why, whenever I filter, I can get the values that I am looking for — since these already exist in my models and I am just basically going back and looking it up using field lookup and filtering.

Example 1: As you can see, I put a default argument “Anywhere” on city.

So, to use Django’s field lookups, the format is field__fieldlookup. I used startswith because I want to get all the cities that have the starting letters of a city — regardless if everything that comes out are different cities.

And then I placed city__starswith inside filter_args with the name “city”. Then I used room_models.Room.objects.filter(**filter_args) since “city” is already a field in my room_models.Room. (Note: ** unpacks filter_args’ contents).

And on my .html file that is connected through render from my .py file, I used context to transfer “rooms” (which contains my filter_args) to the .html file so I can use it. Since I am going to go through hundreds of rooms (which were seeded), I have to use a for loop to be able to get each individual room and their name. (Note: all of these have been made in my models.py and I am now currently only working with my views.py and search.html).

Just to give you some context, this is my Django-Admin and I searched new to see all the rooms that have the words “new” at the beginning. As you can see, the word “new” comes from different cities. This is the same as what I want to achieve on the site.

By using city__startswith and filtering it through my Room model, I am achieving that function. Below is the site:

So when I search for “new”,

Results would show everything under “city” on my model that has “new” at the beginning.

Example 2: Let’s change __startswith to __exact.

Now, even when I search for “new” there will be no results because there is no city that only has “new”. All of the cities that have “new” at the beginning has a word after it.

Example 3: Let’s just change it to __icontains. Which means it is case insensitive (But it doesn’t matter since we put str.capitalize on city).

As you can see, the number of rooms increased from 9 to 14 because we are using the field lookup: icontains.

Now let’s use __lte which means less than or equal to with price. We will be looking into Philippines and their prices.

This is an the Django-Admin — which contains all the fields that we put on the model as well as the information we seeded. All information are made up.

Note: I have already filtered other fields such as city, country and room_type but we will leave them as blank except country since the three have different contents in room_type and city. Because when we filter, all have to be True. In this case, for example purposes, we will only filter the city and the price and then leave the others blank / default.

First let’s try to filter just the country:

We only have three rooms — like what is shown on the Django-Admin.

Now let’s filter the price by adding numbers on the form. On django-admin, two of the rooms are above 10,000 and one is below 10,000. Let’s filter by only having: Since we did price__lte — it means the the price must be equal to 10,000 or less than 10,000.

Now only one room shows up because only one room is less than 10,000.

Now let’s try filtering 3 things: room_type, price(lte) and country. We will still use the Philippines.

If you recall, there are three rooms below 20,000 but only one room is being filtered because we added the room_type in the filtering process. This means out of the three rooms, only one room has the room_type: entire place AND a price of 20,000.