feat: default tags (#66)

Author: Sciator

CHANGELOG.md

@@ -1,5 +1,9 @@
 ## 0.4.0 [unreleased]
 
+### Features
+
+1. [#66](https://github.com/InfluxCommunity/influxdb3-csharp/pull/66): Default Tags for Writes
+
 ## 0.3.0 [2023-10-02]
 
 ### Features

Client.Test/InfluxDBClientWriteTest.cs

@@ -143,6 +143,40 @@ public async Task NotSpecifiedOrg()
         Assert.That(requests[0].RequestMessage.Query, Does.Not.ContainKey("org"));
     }
 
+    [Test]
+    public async Task DefaultTags()
+    {
+        MockServer
+            .Given(Request.Create().WithPath("/api/v2/write").UsingPost())
+            .RespondWith(Response.Create().WithStatusCode(204));
+
+        _client = new InfluxDBClient(new ClientConfig
+        {
+            Host = MockServerUrl,
+            Token = "my-token",
+            Organization = "my-org",
+            Database = "my-database",
+            WriteOptions = new WriteOptions
+            {
+                DefaultTags = new Dictionary<string, string>()
+                {
+                    { "tag1", "default" },
+                    { "tag2", "default" },
+                }
+            }
+        });
+
+        await _client.WritePointAsync(PointData
+            .Measurement("cpu")
+            .SetTag("tag", "c")
+            .SetTag("tag2", "c")
+            .SetField("field", 1)
+        );
+
+        var requests = MockServer.LogEntries.ToList();
+        Assert.That(requests[0].RequestMessage.BodyData?.BodyAsString, Is.EqualTo("cpu,tag=c,tag1=default,tag2=c field=1i"));
+    }
+
     [Test]
     public async Task DatabaseCustom()
     {

Client.Test/Write/PointDataTest.cs

@@ -86,6 +86,24 @@ public void TagEmptyKey()
             Assert.That(point.ToLineProtocol(), Is.EqualTo("h2o,location=europe level=2i"));
         }
 
+        [Test]
+        public void DefaultTags()
+        {
+            var point = PointData.Measurement("h2o")
+                .SetTag("tag2", "val")
+                .SetField("field", 1);
+
+            var defaultTags = new Dictionary<string, string>() {
+                {"tag1", "default"},
+                {"tag2", "--"},
+                {"a", "b"},
+            };
+
+            Assert.That(point.ToLineProtocol(defaultTags: defaultTags), Is.EqualTo("h2o,a=b,tag1=default,tag2=val field=1i"));
+            Assert.That(point.ToLineProtocol(defaultTags: null), Is.EqualTo("h2o,tag2=val field=1i"));
+            Assert.That(point.ToLineProtocol(defaultTags: new Dictionary<string, string>()), Is.EqualTo("h2o,tag2=val field=1i"));
+        }
+
         [Test]
         public void TagEmptyValue()
         {

Client/Config/WriteOptions.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using InfluxDB3.Client.Write;
 
 namespace InfluxDB3.Client.Config;
@@ -33,6 +34,33 @@ public class WriteOptions : ICloneable
     /// </summary>
     public WritePrecision? Precision { get; set; }
 
+    /// <summary>
+    /// Tags added to each point during writing. If a point already has a tag with the same key, it is left unchanged.
+    /// <example>
+    /// <code>
+    /// <![CDATA[
+    /// var _client = new InfluxDBClient(new InfluxDBClientConfigs
+    /// {
+    ///     HostUrl = "some-url",
+    ///     Organization = "org",
+    ///     Database = "database",
+    ///     DefaultTags = new Dictionary \<string, string ()
+    ///     {
+    ///         { "rack", "main" },
+    ///     }
+    /// });
+    /// 
+    /// // Writes with rack=main tag
+    /// await _client.WritePointAsync(PointData
+    ///     .Measurement("cpu")
+    ///     .SetField("field", 1)
+    /// );
+    /// ]]>
+    /// </code>
+    /// </example>
+    /// </summary>
+    public Dictionary<string, string>? DefaultTags { get; set; }
+
     /// <summary>
     /// The threshold in bytes for gzipping the body.
     /// </summary>

Client/InfluxDBClient.cs

@@ -402,7 +402,7 @@ private async Task WriteData(IEnumerable<object> data, string? database = null,
             }
 
             var precisionNotNull = precision ?? _config.WritePrecision;
-            var sb = ToLineProtocolBody(data, precisionNotNull);
+            var sb = ToLineProtocolBody(data, precisionNotNull, _config.WriteOptions?.DefaultTags);
             if (sb.Length == 0)
             {
                 Trace.WriteLine($"The writes: {data} doesn't contains any Line Protocol, skipping");
@@ -437,15 +437,15 @@ public void Dispose()
             _disposed = true;
         }
 
-        private static StringBuilder ToLineProtocolBody(IEnumerable<object?> data, WritePrecision precision)
+        private static StringBuilder ToLineProtocolBody(IEnumerable<object?> data, WritePrecision precision, Dictionary<string, string>? defaultTags = null)
         {
             var sb = new StringBuilder("");
 
             foreach (var item in data)
             {
                 var lineProtocol = item switch
                 {
-                    PointData pointData => pointData.ToLineProtocol(precision),
+                    PointData pointData => pointData.ToLineProtocol(precision, defaultTags),
                     _ => item?.ToString()
                 };
 

Client/Write/PointData.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Globalization;
+using System.Linq;
 using System.Numerics;
 using System.Text;
 
@@ -433,13 +434,14 @@ public PointData Copy()
         /// Transform to Line Protocol.
         /// </summary>
         /// <param name="timeUnit">the timestamp precision</param>
+        /// <param name="defaultTags">Tags added to point</param>
         /// <returns>Line Protocol</returns>
-        public string ToLineProtocol(WritePrecision? timeUnit = null)
+        public string ToLineProtocol(WritePrecision? timeUnit = null, Dictionary<string, string>? defaultTags = null)
         {
             var sb = new StringBuilder();
 
             EscapeKey(sb, _values.GetMeasurement()!, false);
-            AppendTags(sb);
+            AppendTags(sb, defaultTags);
             var appendedFields = AppendFields(sb);
             if (!appendedFields)
             {
@@ -455,11 +457,23 @@ public string ToLineProtocol(WritePrecision? timeUnit = null)
         /// Appends the tags.
         /// </summary>
         /// <param name="writer">The writer.</param>
-        private void AppendTags(StringBuilder writer)
+        /// <param name="defaultTags">Tags added to point</param>
+        private void AppendTags(StringBuilder writer, Dictionary<string, string>? defaultTags = null)
         {
-            foreach (var name in _values.GetTagNames())
+            var allNames = defaultTags == null
+                ? _values.GetTagNames()
+                : _values.GetTagNames().Concat(defaultTags.Keys).ToArray()
+                ;
+            Array.Sort(allNames);
+            var lastName = "" == allNames.FirstOrDefault() ? "_" : "";
+
+            foreach (var name in allNames)
             {
-                var value = _values.GetTag(name);
+                if (name == lastName) continue;
+                lastName = name;
+
+                var value = _values.GetTag(name)
+                    ?? defaultTags.First(kv => kv.Key == name).Value;
 
                 if (string.IsNullOrEmpty(name) || string.IsNullOrEmpty(value))
                 {