Route constraint
A route constraint is a rule attached to a route parameter that restricts route matching to values satisfying a specified condition.
ASP.NET Core in Action, 3e
A route constraint is a rule attached to a route parameter that determines whether a URL value satisfies the requirements for matching a route template.
- How it is used
- Narrows URL values during ASP.NET Core endpoint matching and helps distinguish similar route templates.
- How deep it goes
- Explains parameter syntax, built-in types, combinations, optional values, matching behavior, and validation limits.
- Examples
- Uses integer, GUID, decimal, minimum, length, combined, and optional constraints with matching URL values.
- What you can do after
- Apply it via ASP.NET Core route templates to restrict matches and avoid binding incompatible URL values.
Read how ASP.NET Core in Action, 3e explains route constraint →
Pro ASP.NET Core 7, Tenth Edition
A route constraint is a rule attached to a route parameter that restricts matching to values satisfying a specified condition.
- How it is used
- Restricts URL segment matching so endpoints receive compatible values or closely related routes can be distinguished.
- How deep it goes
- Shows constraint syntax, combinations, URL tests, and ambiguous-route handling, including an endpoint-order workaround.
- Examples
- Tests `/100/true` against int and bool constraints, `/dog/true` against combined constraints, and `/23` against overlapping numeric routes.
- What you can do after
- Operate/configure it with `MapGet` constraints and test URLs for successful matches or ambiguous-route exceptions.
Read how Pro ASP.NET Core 7, Tenth Edition explains route constraint →
Related concepts
- validationcontrasts with · The process of checking data, behavior, systems, models, or results against defined criteria to assess their correctness, suitability, or acceptability.
- route parameterconfigures · A route parameter is a named variable embedded in a URL path whose value is captured from a matching request to identify or select a resource or operation.
- routingconfigures · Routing is the selection of a path, destination, or processing component to direct an item, request, or flow toward an intended endpoint.
- routing middlewareuses · Routing middleware is an ASP.NET Core request-pipeline component that matches incoming requests to endpoints and stores the selected endpoint for subsequent processing.
- overlapping route templateaddresses · An overlapping route template is a route template whose matching rules also match one or more other route templates for at least one URL.
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