feat: Add IsMeasurement option to Column attribute for dynamic measur…

…ement names in POCO classes (#240)

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ### Features
 1. [#239](https://github.com/influxdata/influxdb-client-csharp/pull/239): Add support for Asynchronous queries [LINQ]
+1. [#240](https://github.com/influxdata/influxdb-client-csharp/pull/240): Add IsMeasurement option to Column attribute for dynamic measurement names in POCO classes
 
 ## 3.0.0 [2021-09-17]
 

Client.Core.Test/AbstractTest.cs

@@ -114,13 +114,13 @@ private async Task InfluxDbRequest(HttpRequestMessage request)
             try
             {
                 var response = await httpClient.SendAsync(request);
-                Assert.IsTrue(response.IsSuccessStatusCode);
+                Assert.IsTrue(response.IsSuccessStatusCode, $"Failed to make HTTP request: {response.ReasonPhrase}");
 
                 Thread.Sleep(DefaultInfluxDBSleep);
             }
-            catch (Exception)
+            catch (Exception e)
             {
-                Assert.Fail("Unexpected exception");
+                Assert.Fail("Unexpected exception: " + e);
             }
         }
     }

Client.Core/Attributes.cs

@@ -5,6 +5,7 @@ namespace InfluxDB.Client.Core
     /// <summary>
     /// The annotation is used for mapping POCO class into line protocol.
     /// </summary>
+    [AttributeUsage(AttributeTargets.Class)]
     public sealed class Measurement : Attribute
     {
         public string Name { get; }
@@ -18,10 +19,13 @@ public Measurement(string name)
     /// <summary>
     /// The annotation is used to customize bidirectional mapping between POCO and Flux query result or Line Protocol.
     /// </summary>
+    [AttributeUsage(AttributeTargets.Property)]
     public sealed class Column : Attribute
     {
         public string Name { get; }
 
+        public bool IsMeasurement { get; set; }
+
         public bool IsTag { get; set; }
 
         public bool IsTimestamp { get; set; }

Client.Core/Flux/Internal/AttributesCache.cs

@@ -30,7 +30,7 @@ public PropertyInfo[] GetProperties(Type type)
         }
 
         /// <summary>
-        /// Get Mapping attribute for specified propery.
+        /// Get Mapping attribute for specified property.
         /// </summary>
         /// <param name="property">property of DomainObject</param>
         /// <returns>Property Attribute</returns>

Client.Core/Flux/Internal/FluxResultMapper.cs

@@ -69,6 +69,10 @@ internal object ToPoco(FluxRecord record, Type type)
                 {
                     var attribute = _attributesCache.GetAttribute(property);
 
+                    if (attribute != null && attribute.IsMeasurement)
+                    {
+                        SetFieldValue(poco, property, record.GetMeasurement());
+                    }
                     if (attribute != null && attribute.IsTimestamp)
                     {
                         SetFieldValue(poco, property, record.GetTime());

Client.Linq/IMemberNameResolver.cs

@@ -33,6 +33,7 @@ public interface IMemberNameResolver
 
     public enum MemberType
     {
+        Measurement,
         Tag,
         Field,
         Timestamp,
@@ -52,6 +53,11 @@ public MemberType ResolveMemberType(MemberInfo memberInfo)
 
             if (attribute != null)
             {
+                if (attribute.IsMeasurement)
+                {
+                    return MemberType.Measurement;
+                }
+
                 if (attribute.IsTag)
                 {
                     return MemberType.Tag;

Client.Linq/Internal/Expressions/ColumnName.cs

@@ -18,6 +18,9 @@ public void AppendFlux(StringBuilder builder)
         {
             switch (_memberResolver.ResolveMemberType(_member))
             {
+                case MemberType.Measurement:
+                    builder.Append("_measurement");
+                    break;
                 case MemberType.Timestamp:
                     builder.Append("_time");
                     break;

Client.Linq/Internal/Expressions/MeasurementColumnName.cs

@@ -0,0 +1,22 @@
+using System.Reflection;
+using System.Text;
+
+namespace InfluxDB.Client.Linq.Internal.Expressions
+{
+    internal class MeasurementColumnName : IExpressionPart
+    {
+        private readonly ColumnName _delegate;
+
+        internal MeasurementColumnName(MemberInfo member, IMemberNameResolver memberNameResolver)
+        {
+            _delegate = new ColumnName(member, memberNameResolver);
+        }
+
+        public void AppendFlux(StringBuilder builder)
+        {
+            builder.Append("r[\"");
+            _delegate.AppendFlux(builder);
+            builder.Append("\"]");
+        }
+    }
+}

Client.Linq/Internal/QueryExpressionTreeVisitor.cs

@@ -102,6 +102,9 @@ protected override Expression VisitMember(MemberExpression expression)
             {
                 switch (_context.MemberResolver.ResolveMemberType(expression.Member))
                 {
+                    case MemberType.Measurement:
+                        _expressionParts.Add(new MeasurementColumnName(expression.Member, _context.MemberResolver));
+                        break;
                     case MemberType.Timestamp:
                         _expressionParts.Add(new TimeColumnName(expression.Member, _context.MemberResolver));
                         break;

Client.Test/MeasurementMapperTest.cs

@@ -91,7 +91,36 @@ public void HeavyLoad()
 
             Assert.LessOrEqual(ts.Seconds, 10, $"Elapsed time: {elapsedTime}");
         }
-
+
+        [Test]
+        public void MeasurementProperty()
+        {
+            var poco = new MeasurementPropertyPoco
+            {
+                Measurement = "poco",
+                Tag = "tag val",
+                Value = 15.444,
+                ValueWithoutDefaultName = 20,
+                ValueWithEmptyName = 25d,
+                Timestamp = TimeSpan.FromDays(10)
+            };
+
+            var lineProtocol = _mapper.ToPoint(poco, WritePrecision.S).ToLineProtocol();
+
+            Assert.AreEqual("poco,tag=tag\\ val value=15.444,ValueWithEmptyName=25,ValueWithoutDefaultName=20i 864000", lineProtocol);
+        }
+
+        [Test]
+        public void MeasurementPropertyValidation()
+        {
+            var poco = new BadMeasurementAttributesPoco
+            {
+                Measurement = "poco"
+            };
+
+            Assert.Throws<InvalidOperationException>(() => _mapper.ToPoint(poco, WritePrecision.S));
+        }
+
         private class MyClass
         {
             public override string ToString()
@@ -118,5 +147,33 @@ private class Poco
             [Column(IsTimestamp = true)]
             public Object Timestamp { get; set; }
         }
+
+        private class MeasurementPropertyPoco
+        {
+            [Column(IsMeasurement = true)]
+            public string Measurement { get; set; }
+
+            [Column("tag", IsTag = true)]
+            public string Tag { get; set; }
+
+            [Column("value")]
+            public Object Value { get; set; }
+
+            [Column]
+            public int? ValueWithoutDefaultName { get; set; }
+
+            [Column("")]
+            public Double? ValueWithEmptyName { get; set; }
+
+            [Column(IsTimestamp = true)]
+            public Object Timestamp { get; set; }
+        }
+
+        [Measurement("poco")]
+        private class BadMeasurementAttributesPoco
+        {
+            [Column(IsMeasurement = true)]
+            public string Measurement { get; set; }
+        }
     }
 }

Client.Test/QueryApiTest.cs

@@ -79,6 +79,7 @@ public async Task GenericAndTypeofCalls()
             Assert.AreEqual(13.00, measurements[1].Value);
             Assert.IsAssignableFrom<SyncPoco>(measurementsTypeof[0]);
             var cast = measurementsTypeof.Cast<SyncPoco>().ToList();
+            Assert.AreEqual(measurements[0].Measurement, cast[0].Measurement);
             Assert.AreEqual(measurements[0].Timestamp, cast[0].Timestamp);
             Assert.AreEqual(12.25, cast[0].Value);
             Assert.AreEqual(13.00, cast[1].Value);
@@ -106,6 +107,8 @@ public async Task QueryAsyncEnumerable()
 
         private class SyncPoco
         {
+            [Column(IsMeasurement = true)] public string Measurement { get; set; }
+
             [Column("id", IsTag = true)] public string Tag { get; set; }
 
             [Column("_value")] public double Value { get; set; }

Client/Internal/MeasurementMapper.cs

@@ -35,18 +35,30 @@ internal PointData ToPoint<TM>(TM measurement, WritePrecision precision)
 
             var measurementType = measurement.GetType();
             CacheMeasurementClass(measurementType);
-            
+
             var measurementAttribute = (Measurement) measurementType.GetCustomAttribute(typeof(Measurement));
-            if (measurementAttribute == null)
+            var measurementColumn = CACHE[measurementType.Name].SingleOrDefault(p => p.Column.IsMeasurement);
+
+            if ((measurementAttribute == null) ^ (measurementColumn == null) == false)
             {
                 throw new InvalidOperationException(
-                    $"Measurement {measurement} does not have a {typeof(Measurement)} attribute.");
+                    $"Unable to determine Measurement for {measurement}. Does it have a {typeof(Measurement)} or IsMessage {typeof(Column)} attribute?");
             }
 
-            var point = PointData.Measurement(measurementAttribute.Name);
+            string measurementName =
+                measurementAttribute == null
+                    ? (string)measurementColumn.Property.GetValue(measurement)
+                    : measurementAttribute.Name;
+
+            var point = PointData.Measurement(measurementName);
 
             foreach (var propertyInfo in CACHE[measurementType.Name])
             {
+                if (propertyInfo.Column.IsMeasurement)
+                {
+                    continue;
+                }
+
                 var value = propertyInfo.Property.GetValue(measurement);
                 if (value == null)
                 {