Python嵌套列表理解错误

Question

I'm trying to convert a normal nested iteration into a nest list comp and I'm having trouble.

for k in r.json()['app_list']:
    for i in titles:
        if k['name'] == i['name'] and k['platform'] == i['platform']:
            array.append(session.get(k['api_url'], headers=headers).json())
return array

Works fine, however

return [session.get(k['api_url'], headers=headers).json()
        for i in titles for k in r.json()
        if k['name'] == i['name'] and k['platform'] == i['platform']]

throws this error

if k['name'] == i['name'] and k['platform'] == i['platform']]
TypeError: string indices must be integers

Answer 1

You have your nesting order wrong and you forgot to get the 'app_list' key from the r.json() dictionary.

List comprehension loops are still listed in the same order, left to right as you nest them. In other words, use the same order as your original nested for statements:

return [session.get(k['api_url'], headers=headers).json()
        for k in r.json()['app_list']
        for i in titles
        if k['name'] == i['name'] and k['platform'] == i['platform']]

The above was reached simply by putting everything in the array.append() call at the front , then removing the : colons from the for and if statements and putting the result inside [...] square brackets.

You forgot the ['app_list'] subscription to the r.json() , and that's the actual cause of the exception; r.json() produces a dictionary, so each k was bound to a key from that dictionary, making the k['name'] subscription fail.