48 lines
2.5 KiB
Markdown
48 lines
2.5 KiB
Markdown
---
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title: TastyPie Note 1
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date: 2016-05-10 17:00:00
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tags:
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- tastypie
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- django
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---
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### Flow Through The Request/Response Cycle
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Tastypie can be thought of as a set of class-based view that provide the API functionality. All routing/middleware/response-handling aspectss are the same as a typical Django app. Where the differs is in the view itself.
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Walking through what a GET request to a list endpoint looks like:
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- The `Resource.urls` are checked by Django's url resolvers.
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- On a match for the list view, `Resource.wrap_view('dispatch_list')` is called. `wrap_view` provides basic error handling & allows for returning serilized errors.
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- Because dispatch_list was passed to `wrap_view`, `Resource.dispatch_list` is called next. This is a thin wrapper around `Resource.dispatch`.
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- `dispatch` does a bunch of havy lifting. It ensures:
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- the requested HTTP method is in `allowed_methos` (`method_check`).
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- the class has a method that can handle the request(`get_list`)
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- the user is authenticated(`is_authenticated`)
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- the user has no exceeded their throttle(`throttle_check`).
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At this point, `dispatch` actually calls the requested method (`get_list`).
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- `get_list` does the actual work of API. It does:
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- A fetch of the available objects via `Resource.obj_get_list`. In the case of `ModelResource`, this builds the ORM filters to apply (`ModelResource.build_filters`). It then gets the `QuerySet` via `ModelResource.get_object_list` (which performs `Resource.authorized_read_list` to possibly limit the set the user can work with) and applies the built filters to it.
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- It then sorts the objects based on user input (`ModelResource.apply_sorting`).
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- Then it paginates the results using the supplied `Paginator` & pulls out the data to be serialized.
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- The objects in the page have `full_dehydrate` applied to each of them, causing Tastypie to traslate the raw object data into the fields the endpoint supports.
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- Finally, it calls `Resource.create_response`.
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- `create_response` is a shortcut method that:
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- Determines the desired response format (`Resource.determine_format`).
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- Serializes the data given to it in the proper format.
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- Returns a Django `HttpResponse` (200 OK) with the serialized data.
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- We bubble back up the call stack to `dispatch`. The last thing `dispatch` does is potentially store that a request occured for future throttling (`Resource.log_throttled_access`) then either returns the `HttpResponse` or wraps whatever data came back in a response (so Django doesn't freak out).
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