StringRouteConstraint.cs

// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using System.Globalization;
using Microsoft.AspNetCore.Http;

namespace Microsoft.AspNetCore.Routing.Constraints
{
    /// <summary>
    /// Constrains a route parameter to contain only a specified strign.
    /// </summary>
    public class StringRouteConstraint : IRouteConstraint
    {
        private string _value;

        /// <summary>
        /// Initializes a new instance of the <see cref="StringRouteConstraint"/> class.
        /// </summary>
        /// <param name="value">The constraint value to match.</param>
        public StringRouteConstraint(string value)
        {
            if (value == null)
            {
                throw new ArgumentNullException(nameof(value));
            }

            _value = value;
        }

        /// <inheritdoc />
        public bool Match(HttpContext httpContext, IRouter route, string routeKey, RouteValueDictionary values, RouteDirection routeDirection)
        {
            if (httpContext == null)
            {
                throw new ArgumentNullException(nameof(httpContext));
            }

            if (route == null)
            {
                throw new ArgumentNullException(nameof(route));
            }

            if (routeKey == null)
            {
                throw new ArgumentNullException(nameof(routeKey));
            }

            if (values == null)
            {
                throw new ArgumentNullException(nameof(values));
            }

            object routeValue;

            if (values.TryGetValue(routeKey, out routeValue)
                && routeValue != null)
            {
                var parameterValueString = Convert.ToString(routeValue, CultureInfo.InvariantCulture);

                return parameterValueString.Equals(_value, StringComparison.OrdinalIgnoreCase);
            }

            return false;
        }
    }
}