feat: add response headers to HttpException (#658)

* feat: (WIP) add response headers to HttpException

* chore: (WIP) reformat test code

* feat: (WIP) makes response headers accessible from WriteErrorEvent

* chore: reformat code in recent changes.

* docs: adds examples of handling HTTP Headers in errors.

* chore: tweak wait polling in new example.

* docs: add API doc and update Examples/README.md

* docs: tweaking new example.

* docs: update CHANGELOG.md

* chore: change Headers from raw field to AutoProperty

* chore: explicitly set nullable context for Headers.

---------

Co-authored-by: Jakub Bednář <jakub.bednar@gmail.com>

CHANGELOG.md

@@ -1,5 +1,8 @@
 ## 4.18.0 [unreleased]
 
+### Features:
+1. [#658](https://github.com/influxdata/influxdb-client-csharp/pull/658): Add HttpHeaders as `IEnumerable<RestSharp.HttpParameter>` to `HttpException` and facilitate access in `WriteErrorEvent`.  Includes new example `HttpErrorHandling`.
+
 ### Dependencies
 Update dependencies:
 

Client.Core/Exceptions/InfluxException.cs

@@ -4,6 +4,7 @@
 using System.Linq;
 using System.Net;
 using System.Net.Http;
+using System.Net.Http.Headers;
 using InfluxDB.Client.Core.Internal;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
@@ -56,6 +57,13 @@ public HttpException(string message, int status, Exception exception = null) : b
         /// </summary>
         public int? RetryAfter { get; set; }
 
+#nullable enable
+        /// <summary>
+        ///     The response headers
+        /// </summary>
+        public IEnumerable<HeaderParameter>? Headers { get; private set; }
+#nullable disable
+
         public static HttpException Create(RestResponse requestResult, object body)
         {
             Arguments.CheckNotNull(requestResult, nameof(requestResult));
@@ -162,6 +170,7 @@ public static HttpException Create(object content, IEnumerable<HeaderParameter>
 
             err.ErrorBody = errorBody;
             err.RetryAfter = retryAfter;
+            err.Headers = headers;
 
             return err;
         }

Client.Test/InfluxExceptionTest.cs

@@ -0,0 +1,46 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using InfluxDB.Client.Core.Exceptions;
+using Newtonsoft.Json.Linq;
+using NUnit.Framework;
+using RestSharp;
+
+namespace InfluxDB.Client.Test
+{
+    [TestFixture]
+    public class InfluxExceptionTest
+    {
+        [Test]
+        public void ExceptionHeadersTest()
+        {
+            try
+            {
+                throw HttpException.Create(
+                    JObject.Parse("{\"callId\": \"123456789\", \"message\": \"error in content object\"}"),
+                    new List<HeaderParameter>
+                    {
+                        new HeaderParameter("Trace-Id", "123456789ABCDEF0"),
+                        new HeaderParameter("X-Influx-Version", "1.0.0"),
+                        new HeaderParameter("X-Platform-Error-Code", "unavailable"),
+                        new HeaderParameter("Retry-After", "60000")
+                    },
+                    null,
+                    HttpStatusCode.ServiceUnavailable);
+            }
+            catch (HttpException he)
+            {
+                Assert.AreEqual("error in content object", he?.Message);
+
+                Assert.AreEqual(4, he?.Headers.Count());
+                var headers = new Dictionary<string, string>();
+                foreach (var header in he?.Headers) headers.Add(header.Name, header.Value);
+                Assert.AreEqual("123456789ABCDEF0", headers["Trace-Id"]);
+                Assert.AreEqual("1.0.0", headers["X-Influx-Version"]);
+                Assert.AreEqual("unavailable", headers["X-Platform-Error-Code"]);
+                Assert.AreEqual("60000", headers["Retry-After"]);
+            }
+        }
+    }
+}

Client.Test/ItErrorEventsTest.cs

@@ -0,0 +1,103 @@
+using System;
+using NUnit.Framework;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using InfluxDB.Client.Api.Domain;
+using InfluxDB.Client.Writes;
+
+namespace InfluxDB.Client.Test
+{
+    [TestFixture]
+    public class ItErrorEventsTest : AbstractItClientTest
+    {
+        private Organization _org;
+        private Bucket _bucket;
+        private string _token;
+        private InfluxDBClientOptions _options;
+
+        [SetUp]
+        public new async Task SetUp()
+        {
+            _org = await FindMyOrg();
+            _bucket = await Client.GetBucketsApi()
+                .CreateBucketAsync(GenerateName("fliers"), null, _org);
+
+            //
+            // Add Permissions to read and write to the Bucket
+            //
+            var resource = new PermissionResource(PermissionResource.TypeBuckets, _bucket.Id, null,
+                _org.Id);
+
+            var readBucket = new Permission(Permission.ActionEnum.Read, resource);
+            var writeBucket = new Permission(Permission.ActionEnum.Write, resource);
+
+            var loggedUser = await Client.GetUsersApi().MeAsync();
+            Assert.IsNotNull(loggedUser);
+
+            var authorization = await Client.GetAuthorizationsApi()
+                .CreateAuthorizationAsync(_org,
+                    new List<Permission> { readBucket, writeBucket });
+
+            _token = authorization.Token;
+
+            Client.Dispose();
+
+            _options = new InfluxDBClientOptions(InfluxDbUrl)
+            {
+                Token = _token,
+                Org = _org.Id,
+                Bucket = _bucket.Id
+            };
+
+            Client = new InfluxDBClient(_options);
+        }
+
+
+        [Test]
+        public void HandleEvents()
+        {
+            using (var writeApi = Client.GetWriteApi())
+            {
+                writeApi.EventHandler += (sender, eventArgs) =>
+                {
+                    switch (eventArgs)
+                    {
+                        case WriteSuccessEvent successEvent:
+                            Assert.Fail("Call should not succeed");
+                            break;
+                        case WriteErrorEvent errorEvent:
+                            Assert.AreEqual("unable to parse 'velocity,unit=C3PO mps=': missing field value",
+                                errorEvent.Exception.Message);
+                            var eventHeaders = errorEvent.GetHeaders();
+                            if (eventHeaders == null)
+                            {
+                                Assert.Fail("WriteErrorEvent must return headers.");
+                            }
+
+                            var headers = new Dictionary<string, string> { };
+                            foreach (var hp in eventHeaders)
+                            {
+                                Console.WriteLine("DEBUG {0}: {1}", hp.Name, hp.Value);
+                                headers.Add(hp.Name, hp.Value);
+                            }
+
+                            Assert.AreEqual(4, headers.Count);
+                            Assert.AreEqual("OSS", headers["X-Influxdb-Build"]);
+                            Assert.True(headers["X-Influxdb-Version"].StartsWith('v'));
+                            Assert.AreEqual("invalid", headers["X-Platform-Error-Code"]);
+                            Assert.AreNotEqual("missing", headers.GetValueOrDefault("Date", "missing"));
+                            break;
+                        case WriteRetriableErrorEvent retriableErrorEvent:
+                            Assert.Fail("Call should not be retriable.");
+                            break;
+                        case WriteRuntimeExceptionEvent runtimeExceptionEvent:
+                            Assert.Fail("Call should not result in runtime exception. {0}", runtimeExceptionEvent);
+                            break;
+                    }
+                };
+
+                writeApi.WriteRecord("velocity,unit=C3PO mps=", WritePrecision.S, _bucket.Name, _org.Name);
+            }
+        }
+    }
+}

Client.Test/ItWriteApiAsyncTest.cs

@@ -1,9 +1,11 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Net;
 using System.Threading.Tasks;
 using InfluxDB.Client.Api.Domain;
 using InfluxDB.Client.Core;
+using InfluxDB.Client.Core.Exceptions;
 using InfluxDB.Client.Core.Flux.Domain;
 using InfluxDB.Client.Core.Test;
 using InfluxDB.Client.Writes;
@@ -185,5 +187,28 @@ public async Task WriteULongValues()
 
             Assert.AreEqual(ulong.MaxValue, query[0].Records[0].GetValue());
         }
+
+        [Test]
+        public async Task WriteWithError()
+        {
+            try
+            {
+                await _writeApi.WriteRecordAsync("h2o,location=fox_hollow water_level=");
+                Assert.Fail("Call should fail");
+            }
+            catch (HttpException exception)
+            {
+                Assert.AreEqual("unable to parse 'h2o,location=fox_hollow water_level=': missing field value",
+                    exception.Message);
+                Assert.AreEqual(400, exception.Status);
+                Assert.GreaterOrEqual(4, exception.Headers.Count());
+                var headers = new Dictionary<string, string>();
+                foreach (var header in exception?.Headers) headers.Add(header.Name, header.Value);
+                Assert.AreEqual("OSS", headers["X-Influxdb-Build"]);
+                Assert.AreEqual("invalid", headers["X-Platform-Error-Code"]);
+                Assert.IsTrue(headers["X-Influxdb-Version"].StartsWith('v'));
+                Assert.NotNull(headers["Date"]);
+            }
+        }
     }
 }

Client.Test/WriteApiTest.cs

@@ -4,6 +4,7 @@
 using System.IO;
 using System.Linq;
 using System.Threading;
+using Castle.Core.Smtp;
 using InfluxDB.Client.Api.Domain;
 using InfluxDB.Client.Core;
 using InfluxDB.Client.Core.Exceptions;
@@ -506,6 +507,62 @@ public void WriteRuntimeException()
             Assert.AreEqual(0, MockServer.LogEntries.Count());
         }
 
+        [Test]
+        public void WriteExceptionWithHeaders()
+        {
+            var localWriteApi = _client.GetWriteApi(new WriteOptions { RetryInterval = 1_000 });
+
+            var traceId = Guid.NewGuid().ToString();
+            const string buildName = "TestBuild";
+            const string version = "v99.9.9";
+
+            localWriteApi.EventHandler += (sender, eventArgs) =>
+            {
+                switch (eventArgs)
+                {
+                    case WriteErrorEvent errorEvent:
+                        Assert.AreEqual("just a test", errorEvent.Exception.Message);
+                        var errHeaders = errorEvent.GetHeaders();
+                        var headers = new Dictionary<string, string>();
+                        foreach (var h in errHeaders)
+                            headers.Add(h.Name, h.Value);
+                        Assert.AreEqual(6, headers.Count);
+                        Assert.AreEqual(traceId, headers["Trace-Id"]);
+                        Assert.AreEqual(buildName, headers["X-Influxdb-Build"]);
+                        Assert.AreEqual(version, headers["X-Influxdb-Version"]);
+                        break;
+                    default:
+                        Assert.Fail("Expect only WriteErrorEvents but got {0}", eventArgs.GetType());
+                        break;
+                }
+            };
+            MockServer
+                .Given(Request.Create().WithPath("/api/v2/write").UsingPost())
+                .RespondWith(
+                    CreateResponse("{ \"message\": \"just a test\", \"status-code\": \"Bad Request\"}")
+                        .WithStatusCode(400)
+                        .WithHeaders(new Dictionary<string, string>()
+                        {
+                            { "Content-Type", "application/json" },
+                            { "Trace-Id", traceId },
+                            { "X-Influxdb-Build", buildName },
+                            { "X-Influxdb-Version", version }
+                        })
+                );
+
+
+            var measurement = new SimpleModel
+            {
+                Time = new DateTime(2024, 09, 01, 6, 15, 00),
+                Device = "R2D2",
+                Value = 1976
+            };
+
+            localWriteApi.WriteMeasurement(measurement, WritePrecision.S, "b1", "org1");
+
+            localWriteApi.Dispose();
+        }
+
         [Test]
         public void RequiredOrgBucketWriteApi()
         {

Client/Writes/Events.cs

@@ -1,7 +1,10 @@
 using System;
+using System.Collections.Generic;
 using System.Diagnostics;
 using InfluxDB.Client.Api.Domain;
 using InfluxDB.Client.Core;
+using InfluxDB.Client.Core.Exceptions;
+using RestSharp;
 
 namespace InfluxDB.Client.Writes
 {
@@ -42,6 +45,14 @@ internal override void LogEvent()
         {
             Trace.TraceError($"The error occurred during writing of data: {Exception.Message}");
         }
+
+        /// <summary>
+        /// Get headers from the nested exception.
+        /// </summary>
+        public IEnumerable<HeaderParameter> GetHeaders()
+        {
+            return ((HttpException)Exception)?.Headers;
+        }
     }
 
     /// <summary>