CODEWITHSUNDEEP
pythongoogle-app-engine
Jonas Bolin
Jonas Bolin

Reputation: 616

KeyError when iterating on lists

I'm sorry if this is a stupid question but I've been thinking about it a lot and looked through Jinja docs but so far to no avail. Short background: I've just completed Udacity's CS101 and CS253 and am about to help a friend build a booking system for a yoga studio. It's all on Google Appengine, just like

I want to have a list of available yoga classes similar to this:

Monday

Dynamic Yoga with Mary 6pm

Soft yoga with Susie 8pm

Wednesday

Hatha yoga with Bob 5pm

Hot yoga with Alice 7pm

So I want to fetch the list of classes, then see if there is a yoga class on Monday. If there is one I add 'Monday' to the list and all the Monday classes, and so on with all the other days. Like this:

day_output1 = ['Monday',['Dynamic Yoga with Mary 6pm'],['Soft yoga with Su..']]

day_output2 = ['Wednesday',['Hatha yoga with Bob 5pm'],['Hot yoga with Al...']]

And then add these to a list for the whole week, which is then sent to the template:

weekly_classes = [day_output1, day_output2]

Right now I'm getting a KeyError, which means it doesnt find the Key, but I dont understand why?

  File "/Users/username/YogaSchemat/yogaschema/main.py", line 113, in get
    day = d[n]
KeyError: 1

With this code... Thanks in advance guys!

d = {
"1": 'Monday', 
"2": 'Tuesday', 
"3": 'Wednesday', 
"4": 'Thursday', 
"5": 'Friday', 
"6": 'Saturday', 
"7": 'Sunday'
}
def get_classes():
    yoga_classes = Schema.all() #appengine DB request
    if yoga_classes:
        weekly_classes = [] #list that will be sent to template
        for n in range(1,8):
            for e in yoga_classes:
                if e.weekday == n:
                    day = d[n] #getting weekday from d
                    class_details = [] #
                    class_details.append(e)
                    day_output = [day,class_details]
                    weekly_classes.append(day_output)
    self.response.out.write(weekly_classes)

Upvotes: 1

Views: 1248

Answers (1)

Martijn Pieters
Martijn Pieters

Reputation: 1122172

You are using string keys in your d mapping, but are looking up a integer instead.

In this case, you should use a list instead:

d = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday']

# ...
for n in range(7):
    day = d[n]

with n between 0 and 6, mapping directly to the names of the week at those positions in the d list.

Alternatively, you could use integers as keys instead:

d = {
    1: 'Monday', 
    2: 'Tuesday', 
    3: 'Wednesday', 
    4: 'Thursday', 
    5: 'Friday', 
    6: 'Saturday', 
    7: 'Sunday'
}

but since your keys are sequential, you may as well save the space.

Upvotes: 1

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