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Advent of Code 2020: "Toboggan Trajectory" - Day 3

Have to admit, on first glance this challenge looks a bit complicated. It's well suited for languages which can do string manipulations, but it's not well suited for PostgreSQL. Earlier today I already looked at this problem together with the kid, in Python. Therefore I already knew that I have to jump multiple rows as well. To sum it up: adjust x, including overruns, jump multiple rows in y direction, count trees along the way. All in a single SQL query.

Decided to do the map search in a pl/pgSQL instead, and write a function for it.

Task 1: you get a map of "." and "#", where the "#" are trees. You get instructions to move a certain number of steps into x and y direction, and see if there is a tree. Then repeat until the end of the map. A detail problem is that the number of fields in x direction is smaller than the y direction. There are no clear instructions how to handle this, but the correct solution is to just start at the leftmost position again.

Task 2: Repeat the task from task 1, but 5 times with 5 different instructions for x and y movement. The resulting numbers are to be multiplied.

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Advent of Code 2020: "Password Philosophy" - Day 2

Day 2, another challenge: fix a broken password database. In order to do that, the passwords which violate the policy must be identified.

Task 1: I get a string, consisting of 2 numbers, a letter, and a password string. Check how many passwords have count(letter) which is between number 1 and number 2.

Task 2: The numbers are positions in the password string (beginning by 1, not 0). Exactly one of the two letters in the string must match the letter.


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Advent of Code 2020: "Report Repair" - Day 1

Started "Advent of Code" with the kid, the kid is polishing the Python (and English) skills. I thought I better do this in SQL.

The Task 1 for "Day 1" is: you get 200 numbers from the accounting department, find the two which in sum are 2020. This two numbers multiplied is the result of the task.

Task 2 is like task 1, except it's using three numbers. All three in sum will be 2020, and then multiply these three and that is the result.


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Django: Remove default entries from admin menu

The Django administration site comes with a couple of default entries, depending on which apps and middleware is installed.

Usually there is at least "Users" and "Groups", and if the quite common "allauth" is installed, then there is also "Site", "SocialApp", "SocialAccount", and "SocialToken". They are not always necessary, especially when no Social Login is used. Or why have the "Site" administration when only Site=1 is used?

With a few tricks these can be removed from the admin menu.


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Django: disable inline option to add new referenced objects

The Django Web Framework makes it quite easy to add new referenced objects in the admin menu.

Let's say the model has two foreign keys in it:

class TeamMember(models.Model):
    team = models.ForeignKey(Team, on_delete=models.CASCADE, verbose_name=_("Team"))
    user = models.ForeignKey(CustomUser, on_delete=models.CASCADE, verbose_name=_("User"))

And the admin form:

class TeamMemberForm(forms.ModelForm):
    class Meta:
        model = TeamMember

class CustomTeamMemberAdmin(admin.ModelAdmin):
    form = TeamMemberForm
    add_form = TeamMemberForm
    model = TeamMember
    fieldsets = [
        (None,      {'fields': ['team', 'user']}),
    ], CustomTeamMemberAdmin)

Then Django will show small a small green "Django add reference" sign next to the fields:

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Use namespace as global variable in Ansible Jinja templates

A simple task, or so I thought: in a Jinja template keep track of the number of items in a loop. And then use that count afterwards.

Disclaimer: the number of items is not equal the number of times the loop runs, so I can't use the loop variables.

Turns out that Jinja has other opinions, and variables inside a loop are all local. When a variable is changed inside the loop, the scoop of the variable stays local, and once the loop ends the original value of the variable is restored. That's even true for variables which are created outside the loop.


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