Fix pipe char encoding issue (#2345)

* Fix #2207: Prevent Uri constructor from re-encoding pipe character when encode=false

The issue was that when AddQueryParameter was called with encode=false,
the pipe character (|) was still being encoded to %7C. This happened
because the AddQueryString method was creating a new Uri object directly,
and the Uri constructor automatically encodes certain characters including
the pipe character.

The fix uses UriBuilder instead, which preserves the query string as-is
without re-encoding it. This ensures that when encode=false is specified,
characters like pipe (|) remain unencoded as expected.

Added test case to verify pipe character is not encoded when encode=false.

* Fix issue #2207: Preserve unencoded characters in query parameters when encode=false

- Modified BuildUriExtensions to add BuildUriString method that returns a string URI
- Updated RestClient.Async to use string URI for HttpRequestMessage to preserve unencoded characters
- Added RawUrl property to RequestBodyCapturer to capture the actual URL string sent over HTTP
- Added integration test to verify pipe character is not encoded when encode=false
- All existing tests pass

* Fix pipe encoding issue

* Remove usage of BuildUrl

Author: alexeyzimarev

src/RestSharp/Authenticators/OAuth/OAuth1Authenticator.cs

@@ -245,7 +245,7 @@ internal static void AddOAuthData(
                 "Using query parameters in the base URL is not supported for OAuth calls. Consider using AddDefaultQueryParameter instead."
             );
 
-        var url              = client.BuildUri(request).ToString();
+        var url              = client.BuildUriString(request);
         var queryStringStart = url.IndexOf('?');
 
         if (queryStringStart != -1) url = url[..queryStringStart];

src/RestSharp/BuildUriExtensions.cs

@@ -23,18 +23,23 @@ public static class BuildUriExtensions {
         /// </summary>
         /// <param name="request">Request instance</param>
         /// <returns></returns>
-        public Uri BuildUri(RestRequest request) {
-            DoBuildUriValidations(client, request);
+        public Uri BuildUri(RestRequest request) => new(client.BuildUriString(request));
 
-            var (uri, resource) = client.Options.BaseUrl.GetUrlSegmentParamsValues(
-                request.Resource,
-                client.Options.Encode,
-                request.Parameters,
-                client.DefaultParameters
-            );
-            var mergedUri = uri.MergeBaseUrlAndResource(resource);
+        /// <summary>
+        /// Builds the URI string for the request. This method returns a string instead of a Uri object
+        /// to preserve unencoded characters when encode=false is specified for query parameters.
+        /// </summary>
+        /// <param name="request">Request instance</param>
+        /// <returns></returns>
+        [PublicAPI]
+        public string BuildUriString(RestRequest request) {
+            var mergedUri = client.BuildUriWithoutQueryParameters(request);
             var query     = client.GetRequestQuery(request);
-            return mergedUri.AddQueryString(query);
+
+            if (query == null) return mergedUri.AbsoluteUri;
+
+            var separator = mergedUri.AbsoluteUri.Contains('?') ? "&" : "?";
+            return $"{mergedUri.AbsoluteUri}{separator}{query}";
         }
 
         /// <summary>

src/RestSharp/Request/UriExtensions.cs

@@ -41,10 +41,10 @@ public static Uri MergeBaseUrlAndResource(this Uri? baseUrl, string? resource) {
     public static Uri AddQueryString(this Uri uri, string? query) {
         if (query == null) return uri;
 
-        var absoluteUri = uri.AbsoluteUri;
-        var separator   = absoluteUri.Contains('?') ? "&" : "?";
+        var builder = new UriBuilder(uri);
+        builder.Query = builder.Query.Length > 1 ? $"{builder.Query[1..]}&{query}" : query;
 
-        return new($"{absoluteUri}{separator}{query}");
+        return builder.Uri;
     }
 
     public static UrlSegmentParamsValues GetUrlSegmentParamsValues(

src/RestSharp/RestClient.Async.cs

@@ -111,9 +111,10 @@ async Task<HttpResponse> ExecuteRequestAsync(RestRequest request, CancellationTo
         using var requestContent = new RequestContent(this, request);
 
         var httpMethod = AsHttpMethod(request.Method);
-        var url        = this.BuildUri(request);
+        var urlString  = this.BuildUriString(request);
+        var url        = new Uri(urlString);
 
-        using var message = new HttpRequestMessage(httpMethod, url);
+        using var message = new HttpRequestMessage(httpMethod, urlString);
         message.Content              = requestContent.BuildContent();
         message.Headers.Host         = Options.BaseHost;
         message.Headers.CacheControl = request.CachePolicy ?? Options.CachePolicy;

test/RestSharp.InteractiveTests/AuthenticationTests.cs

@@ -39,8 +39,7 @@ public static async Task Can_Authenticate_With_OAuth_Async_With_Callback(Twitter
 
         request = new($"oauth/authorize?oauth_token={oauthToken}");
 
-        var url = client.BuildUri(request)
-            .ToString();
+        var url = client.BuildUriString(request);
 
         Console.WriteLine($"Open this URL in the browser: {url} and complete the authentication.");
         Console.Write("Enter the verifier: ");

test/RestSharp.Tests.Integrated/DefaultParameterTests.cs

@@ -35,4 +35,17 @@ public async Task Should_not_throw_exception_when_name_is_null() {
 
         await client.ExecuteAsync(request);
     }
+
+    [Fact]
+    public async Task Should_not_encode_pipe_character_when_encode_is_false() {
+        using var client = new RestClient(server.Url!);
+
+        var request = new RestRequest("capture");
+        request.AddQueryParameter("ids", "in:001|116", false);
+
+        await client.ExecuteAsync(request);
+
+        var query = _capturer.RawUrl.Split('?')[1];
+        query.Should().Contain("ids=in:001|116");
+    }
 }

test/RestSharp.Tests.Shared/Fixtures/RequestBodyCapturer.cs

@@ -7,6 +7,7 @@ public class RequestBodyCapturer {
     public bool   HasBody     { get; private set; }
     public string Body        { get; private set; }
     public Uri    Url         { get; private set; }
+    public string RawUrl      { get; private set; }
 
     public bool CaptureBody(string content) {
         Body    = content;
@@ -23,6 +24,7 @@ public bool CaptureHeaders(IDictionary<string, string[]> headers) {
     }
 
     public bool CaptureUrl(string url) {
+        RawUrl = url;
         Url = new(url);
         return true;
     }

test/RestSharp.Tests/Auth/OAuth1SignatureTests.cs

@@ -37,7 +37,7 @@ public void Generates_correct_signature_base() {
         var requestParameters = _request.Parameters.ToWebParameters().ToArray();
         var parameters        = new WebPairCollection();
         parameters.AddRange(requestParameters);
-        var url = _client.BuildUri(_request).ToString();
+        var url = _client.BuildUriString(_request);
         _workflow.RequestUrl = url;
         var oauthParameters = _workflow.BuildProtectedResourceSignature(method, parameters);
         oauthParameters.Parameters.AddRange(requestParameters);

test/RestSharp.Tests/Auth/OAuth1Tests.cs

@@ -46,7 +46,7 @@ public async Task Can_Authenticate_OAuth1_With_Querystring_Parameters() {
         authenticator.ParameterHandling = OAuthParameterHandling.UrlOrPostParameters;
         await authenticator.Authenticate(client, request);
 
-        var requestUri = client.BuildUri(request);
+        var requestUri = new Uri(client.BuildUriString(request));
         var actual     = requestUri.ParseQuery().Select(x => x.Key).ToList();
 
         actual.Should().BeEquivalentTo(expected);

test/RestSharp.Tests/Parameters/UrlSegmentTests.cs

@@ -1,7 +1,8 @@
 namespace RestSharp.Tests.Parameters;
 
 public class UrlSegmentTests {
-    const string BaseUrl = "http://localhost:8888/";
+    const string BaseUrlNoTrail = "http://localhost:8888";
+    const string BaseUrl        = $"{BaseUrlNoTrail}/";
 
     [Fact]
     public void AddUrlSegmentWithInt() {
@@ -22,10 +23,10 @@ public void AddUrlSegmentModifiesUrlSegmentWithInt() {
 
         var path     = string.Format(pathTemplate, $"{{{name}}}");
         var request  = new RestRequest(path).AddUrlSegment(name, urlSegmentValue);
-        var expected = string.Format(pathTemplate, urlSegmentValue);
+        var expected = $"{BaseUrlNoTrail}{string.Format(pathTemplate, urlSegmentValue)}";
 
         using var client = new RestClient(BaseUrl);
-        var       actual = client.BuildUri(request).AbsolutePath;
+        var       actual = client.BuildUriString(request);
 
         expected.Should().BeEquivalentTo(actual);
     }
@@ -38,11 +39,11 @@ public void AddUrlSegmentModifiesUrlSegmentWithString() {
 
         var path     = string.Format(pathTemplate, $"{{{name}}}");
         var request  = new RestRequest(path).AddUrlSegment(name, urlSegmentValue);
-        var expected = string.Format(pathTemplate, urlSegmentValue);
+        var expected = $"{BaseUrlNoTrail}{string.Format(pathTemplate, urlSegmentValue)}";
 
         using var client = new RestClient(BaseUrl);
 
-        var actual = client.BuildUri(request).AbsolutePath;
+        var actual = client.BuildUriString(request);
 
         expected.Should().BeEquivalentTo(actual);
     }
@@ -73,14 +74,15 @@ public void UrlSegmentParameter_WithValueWithEncodedSlash_CanLeaveEncodedSlash(s
 
     [Fact]
     public void AddSameUrlSegmentTwice_ShouldReplaceFirst() {
-        var client  = new RestClient();
-        var request = new RestRequest("https://api.example.com/orgs/{segment}/something");
+        const string host    = "https://api.example.com";
+        var          client  = new RestClient();
+        var          request = new RestRequest($"{host}/orgs/{{segment}}/something");
         request.AddUrlSegment("segment", 1);
-        var url1 = client.BuildUri(request);
+        var url1 = client.BuildUriString(request);
         request.AddUrlSegment("segment", 2);
-        var url2 = client.BuildUri(request);
-        
-        url1.AbsolutePath.Should().Be("/orgs/1/something");
-        url2.AbsolutePath.Should().Be("/orgs/2/something");
+        var url2 = client.BuildUriString(request);
+
+        url1.Should().Be($"{host}/orgs/1/something");
+        url2.Should().Be($"{host}/orgs/2/something");
     }
 }