模板中的Django对象查找

Question

I am going through the Django project tutorial, and in this section it says:

The template system uses dot-lookup syntax to access variable attributes. In the example of {{ question.question_text }}, first Django does a dictionary lookup on the object question. Failing that, it tries an attribute lookup – which works, in this case. If attribute lookup had failed, it would've tried a list-index lookup.

Does this mean that the Django question is a dictionary object, and in the first instance, looks for question_text as the key, and if found, returns the value? Beyond this, I can't visualise what the two fall-back options are doing.

Answer 1

Does this mean that the Django question is a dictionary object, and in the first instance, looks for question_text as the key, and if found, returns the value? Beyond this, I can't visualise what the two fall-back options are doing.

question doesn't have to be a literal dict for the first option to work. It needs to be dictionary-like. That is, question['question_text'] works in Python.

The first fallback refers to regular Python dot notation. For example, if either of these works in Python:

question.question_text  # or
question.question_text()

then question.question_text will work in the template returning the Python value. Note that parentheses are omitted in both cases.

The final fallback is numeric indexing. For example, if question is a list and this works in Python:

question[0]

then question.0 will work in the template, returning the value of question[0] .