Route Constraints
Route constraints let you restrict how the parameters in the route template are matched. The general syntax is "{parameter:constraint}". For example:
[Route("users/{id:int}"]
public User GetUserById(int id) { ... }
[Route("users/{name}"]
public User GetUserByName(string name) { ... }Here, the first route will only be selected if the "id" segment of the URI is an integer. Otherwise, the second route will be chosen.
The following table lists the constraints that are supported.
| Constraint | Description | Example |
|---|---|---|
| alpha | Matches uppercase or lowercase Latin alphabet characters (a-z, A-Z) | {x:alpha} |
| bool | Matches a Boolean value. | {x:bool} |
| datetime | Matches a DateTime value. | {x:datetime} |
| decimal | Matches a decimal value. | {x:decimal} |
| double | Matches a 64-bit floating-point value. | {x:double} |
| float | Matches a 32-bit floating-point value. | {x:float} |
| guid | Matches a GUID value. | {x:guid} |
| int | Matches a 32-bit integer value. | {x:int} |
| length | Matches a string with the specified length or within a specified range of lengths. | {x:length(6)} {x:length(1,20)} |
| long | Matches a 64-bit integer value. | {x:long} |
| max | Matches an integer with a maximum value. | {x:max(10)} |
| maxlength | Matches a string with a maximum length. | {x:maxlength(10)} |
| min | Matches an integer with a minimum value. | {x:min(10)} |
| minlength | Matches a string with a minimum length. | {x:minlength(10)} |
| range | Matches an integer within a range of values. | {x:range(10,50)} |
| regex | Matches a regular expression. | {x:regex(^\d{3}-\d{3}-\d{4}$)} |
Notice that some of the constraints, such as "min", take arguments in parentheses. You can apply multiple constraints to a parameter, separated by a colon.
[Route("users/{id:int:min(1)}")]
public User GetUserById(int id) { ... }