![]() ![]() Which with more familiarity may also implicitly handle the int:int:int syntactic sugar of slice objects for many container/sequence types in Python: > The operator is available as a specialized alias for _getitem_, > Some implementations of _getitem_ are designed to handle different types as input, such as when bound to lists, which as above handles ints and slices. Type "help", "copyright", "credits" or "license" for more information. The method is how you retrieve one or more items from a container or sequence object, like a list: Python 3.10.4 (main, Jun 29 2022, 12:14:53) on linux #Spacenet inc. wv internet codeIn summary, magic methods (or their overrides) increase code readability and developer experience/convenience. # This is a common pattern in Django templates. Resulting to these convenient patterns: # Instead of `for field in form.fields`. These forms inherit from BaseForm, and have these overridden magic methods (simplified version): def _iter_(self): In Django, you could declare forms like this (includes ModelForm): class ArticleForm(.): With these, you could now have a more intuitive accessors: This is the simplified version: def _getitem_(self, key): Django overridden the _getitem_ and _get_ in MultiValueDict. ![]() Given that the QueryDict values are transformed into lists, they will need to be accessed then like this (same idea with request.GET):īut, these are horrible ways to access the data. This class exists to solve the irritating problem raised by cgi.parse_qs, which returns a list for every key. MultiValueDict's docstring explains though why it needs to auto-convert this to list format: When you submit data, say user_id=42, QueryDict will be stored/represented as: This dict is of type QueryDict which inherits from MultiValueDict. When you submit GET/POST data in Django, it will be stored in Django's request object as request.GET/ request.POST dict. Print p.dob # print (Date or Month or ) Year of the 'date of birth'ĭjango core has several interesting and nifty usages for magic methods, including _getitem_. e.g., print p.name # print first (or last) name With the help of _getitem_ method, the user can access the indexed attributes. Suppose one user input is as follows: p = Person(name = 'Jonab Gutu', age = 20, dob=(1, 1, 1999)) P.dob = p.dob # or, p.dob = p.dob._getitem_(indx) # Constants that can be used to index date of birth's Date-Month-Year The _getitem_ method is written in a way that one can access the indexed instance attributes, such as first or last name, day, month or year of the dob, etc. Here I am showing this with an example class Person that can be instantiated by 'name', 'age', and 'dob' (date of birth). It is very useful for a quick lookup of instance attributes. The magic method _getitem_ is basically used for accessing list items, dictionary entries, array elements etc. get more than one floor's data at a time - it depends on what you need. Whether you use _setitem_ like this really depends on how you plan to abstract your data - in this case we have decided to treat a building as a container of floors (and you could also implement an iterator for the Building, and maybe even the ability to slice - i.e. class Building(object):ĭef _setitem_(self, floor_number, data): We could however use _getitem_ (and its counterpart _setitem_) to make the usage of the Building class 'nicer'. Without using _getitem_ we would have a class like this : class Building(object):īuilding1 = Building(4) # Construct a building with 4 floors Within the data for the building it includes a number of attributes, including descriptions of the companies that occupy each floor : Cong Ma does a good job of explaining what _getitem_ is used for - but I want to give you an example which might be useful. ![]()
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