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Make routing constraints use the fields format

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This makes routing more in line with the rest of Cowboy and
allows us to use cowboy_constraints directly.
This commit is contained in:
Loïc Hoguin 2014-09-23 21:36:52 +03:00
parent f1c3b6d76f
commit 25259671f5
3 changed files with 36 additions and 70 deletions
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26
doc/src/guide/routing.ezdoc
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@ -191,26 +191,16 @@ HostMatch = "*".
After the matching has completed, the resulting bindings can be tested
against a set of constraints. Constraints are only tested when the
binding is defined. They run in the order you defined them. The match
will succeed only if they all succeed.
will succeed only if they all succeed. If the match fails, then Cowboy
tries the next route in the list.
They are always given as a two or three elements tuple, where the first
element is the name of the binding, the second element is the constraint's
name, and the optional third element is the constraint's arguments.
The format used for constraints is the same as match functions in
`cowboy_req`: they are provided as a list of fields which may have
one or more constraints. While the router accepts the same format,
it will skip fields with no constraints and will also ignore default
values, if any.
The following constraints are currently defined:
* {Name, int}
* {Name, function, fun ((Value) -> true | {true, NewValue} | false)}
The `int` constraint will check if the binding is a binary string
representing an integer, and if it is, will convert the value to integer.
The `function` constraint will pass the binding value to a user specified
function that receives the binary value as its only argument and must
return whether it fulfills the constraint, optionally modifying the value.
The value thus returned can be of any type.
Note that constraint functions SHOULD be pure and MUST NOT crash.
Read more about ^constraints^.
:: Compilation