Django模型输入的所有字段以逗号分隔

Question

The code in the two if-blocks smells to violate DRY. How can it be written more generic?

selected_class = eval(choice)            # bad  (see comments)
selected_class = getattr(models, choice) # good (see comments)
records = selected_class.objects.all()
if (choice == 'Treatment'):
    for record in records:
        response.write(str(record.id) + ',' + str(record.available_hours) + '\n')
if (choice == 'Patient'):
    for record in records:
        response.write(str(record.id) + ',' + record.first_name + '\n')

I could write in each model (Treatment and Patient) a method 'make_csv'. But, there must be a better way.

Answer 1

A simple solution:

for record in records:
    if choice == 'Treatment':
        item = str(record.available_hours)
    elif choice == 'Patient':
        item = record.first_name
    response.write('{},{}\n'.format(record.id, item))

Or, if you want a slightly more complex solution that avoids repeating the if :

choices_dict = {
    'Treatment': 'available_hours',
    'Patient': 'first_name',
}

record_field = choices_dict[choice]

for record in records:
    item = getattr(record, record_field) 
    response.write('{},{}\n'.format(record.id, item))

It's also more flexible in case you may want to change or add options to choices_dict , but that may not be relevant.