Pecan - route

object-dispatch

Pecan Use object-dispatch The routing policy will HTTP The request is mapped to a controller.

This strategy uses / Split into lists , Then from the root controller Start looking for the corresponding layer by layer controller.

Example ：

Online store pair /catalog/books/bestsellers The requests are divided into catalog,books and bestsellers. Next ,Pecan Will find on the root controller catalog. And then in catalog Object books, In the end in books Find bestsellers Method .

from pecan import expose

class BooksController(object):
    @expose()
    def index(self):
        return "Welcome to book section."

    @expose()
    def bestsellers(self):
        return "We have 5 books in the top 10."

class CatalogController(object):
    @expose()
    def index(self):
        return "Welcome to the catalog."

    books = BooksController()

class RootController(object):
    @expose()
    def index(self):
        return "Welcome to store.example.com!"

    @expose()
    def hours(self):
        return "Open 24/7 on the web."

    catalog = CatalogController()

Sometimes , Standard object dispatch routing is not sufficient to URL Route to the controller correctly .Pecan Several methods are provided to simplify the object dispatch system , To deal with... With more control url, Including special _lookup()、_default() and _route() Method . These methods can be defined on the controller object to handle all or part of URL Provide additional flexibility .

_lookup

_lookup() Special methods provide a way to deal with URL Part of , Then return a new controller object to route to the rest .

_lookup() Method can accept one or more parameters , I.e. to be handled URL Path segment ( Split into /)._lookup() You should also accept variable location parameters that represent the rest of the path , And should include any part of the path that it does not handle in the return value . The following example uses a *remainder list , This list will be passed to the returning controller when the object scheduling algorithm continues .

In addition to being used to dynamically create controllers , When no other controller method matches URL And there's no _default() When the method is used ,_lookup() Called as a last resort .

Example ：

HTTP GET /8/name The request will return primary_key == 8 The name of the student .

from pecan import expose, abort
from somelib import get_student_by_name

class StudentController(object):
    def __init__(self, student):
        self.student = student

    @expose()
    def name(self):
        return self.student.name

class RootController(object):
    @expose()
    def _lookup(self, primary_key, *remainder):
        student = get_student_by_primary_key(primary_key)
        if student:
            return StudentController(student), remainder
        else:
            abort(404)

_default

When the request path does not match the corresponding method ,_default Will be called .

Example ：

/spanish Will be routed to RootController._default()

from pecan import expose

class RootController(object):
    @expose()
    def english(self):
        return 'hello'

    @expose()
    def french(self):
        return 'bonjour'

    @expose()
    def _default(self):
        return 'I cannot say hello in that language'

_route

_route() Method allows the controller to completely cover Pecan The routing mechanism of .Pecan Self use _route() Method to realize its RestController. If you want to Pecan Design an alternative routing system , Then define a definition _route() The basic controller class of the method will give you full control .