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]
 
@@ -11,7 +12,6 @@ Adds a `Type` overload for POCOs to `QueryAsync`. This will add `object ConvertT
 ### Features
 1. [#232](https://github.com/influxdata/influxdb-client-csharp/pull/232): Add a `Type` overload for POCOs to `QueryAsync`.
 1. [#233](https://github.com/influxdata/influxdb-client-csharp/pull/233): Add possibility to follow HTTP redirects
-1. [#239](https://github.com/influxdata/influxdb-client-csharp/pull/239): Add support for Asynchronous queries [LINQ]
 
 ### Bug Fixes
 1. [#236](https://github.com/influxdata/influxdb-client-csharp/pull/236): Mapping `long` type into Flux AST [LINQ]

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.Test/DomainObjects.cs

@@ -37,6 +37,18 @@ class SensorDateTimeOffset
         [Column(IsTimestamp = true)] public DateTimeOffset Timestamp { get; set; }
     }
 
+    class SensorWithCustomMeasurement
+    {
+        [Column(IsMeasurement = true)]
+        public string Measurement { get; set; }
+
+        [Column("sensor_id", IsTag = true)]
+        public string SensorId { get; set; }
+
+        [Column("data")]
+        public int Value { get; set; }
+    }
+
     class SensorCustom
     {
         public Guid Id { get; set; }

Client.Linq.Test/InfluxDBQueryVisitorTest.cs

@@ -428,6 +428,36 @@ where month11 > s.Timestamp
             }
         }
 
+        [Test]
+        public void ResultOperatorByMeasurement()
+        {
+            var settings = new QueryableOptimizerSettings
+            {
+                DropMeasurementColumn = false
+            };
+
+            var query = from s in InfluxDBQueryable<SensorWithCustomMeasurement>.Queryable("my-bucket", "my-org", _queryApi, settings)
+                        where s.Value > 10
+                        where s.Measurement == "my-measurement"
+                        select s;
+            var visitor = BuildQueryVisitor(query);
+
+            const string expected = "start_shifted = int(v: time(v: p2))\n\nfrom(bucket: p1) " +
+                                    "|> range(start: time(v: start_shifted)) " +
+                                    "|> filter(fn: (r) => (r[\"_measurement\"] == p4)) " +
+                                    "|> pivot(rowKey:[\"_time\"], columnKey: [\"_field\"], valueColumn: \"_value\") " +
+                                    "|> drop(columns: [\"_start\", \"_stop\"]) " +
+                                    "|> filter(fn: (r) => (r[\"data\"] > p3))";
+
+            Assert.AreEqual(expected, visitor.BuildFluxQuery());
+
+            var ast = visitor.BuildFluxAST();
+
+            var measurementAssignment = ((OptionStatement)ast.Body[3]).Assignment as VariableAssignment;
+            Assert.AreEqual("p4", measurementAssignment?.Id.Name);
+            Assert.AreEqual("my-measurement", (measurementAssignment?.Init as StringLiteral)?.Value);
+        }
+
         [Test]
         public void TimestampAsDateTimeOffset()
         {

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/InfluxDBQueryable.cs

@@ -18,17 +18,50 @@ public class QueryableOptimizerSettings
         public QueryableOptimizerSettings()
         {
             QueryMultipleTimeSeries = false;
+            DropMeasurementColumn = true;
+            DropStartColumn = true;
+            DropStopColumn = true;
         }
 
         /// <summary>
         /// Gets or sets whether the drive is used to query multiple time series.
         /// Setting this variable to true will change how the produced Flux Query looks like:
         /// <list type="bullet">
-        /// <item>appends <a href="https://docs.influxdata.com/influxdb/v2.0/reference/flux/stdlib/built-in/transformations/group/">group operator</a></item>
-        /// <item>enable use default sorting: <i>sort(columns: ["_time"], desc: false)</i></item>
+        /// <item>Appends <a href="https://docs.influxdata.com/flux/v0.x/stdlib/universe/group/">group operator</a></item>
+        /// <item>Enable use default sorting: <i>sort(columns: ["_time"], desc: false)</i></item>
         /// </list>
         /// </summary>
         public bool QueryMultipleTimeSeries { get; set; }
+
+        /// <summary>
+        /// Gets or sets whether the _measurement column will be dropped from query results.
+        /// Setting this variable to true will change how the produced Flux Query looks like:
+        /// <list type="bullet">
+        /// <item>Appends <a href="https://docs.influxdata.com/flux/v0.x/stdlib/universe/drop/">drop operator</a></item>
+        /// <item>Drops the _measurement column: <i>drop(columns: ["_measurement"])</i></item>
+        /// </list>
+        /// </summary>
+        public bool DropMeasurementColumn { get; set; }
+
+        /// <summary>
+        /// Gets or sets whether the _start column will be dropped from query results.
+        /// Setting this variable to true will change how the produced Flux Query looks like:
+        /// <list type="bullet">
+        /// <item>Appends <a href="https://docs.influxdata.com/flux/v0.x/stdlib/universe/drop/">drop operator</a></item>
+        /// <item>Drops the _start column: <i>drop(columns: ["_start"])</i></item>
+        /// </list>
+        /// </summary>
+        public bool DropStartColumn { get; set; }
+
+        /// <summary>
+        /// Gets or sets whether the _stop column will be dropped from query results.
+        /// Setting this variable to true will change how the produced Flux Query looks like:
+        /// <list type="bullet">
+        /// <item>Appends <a href="https://docs.influxdata.com/flux/v0.x/stdlib/universe/drop/">drop operator</a></item>
+        /// <item>Drops the _stop column: <i>drop(columns: ["_stop"])</i></item>
+        /// </list>
+        /// </summary>
+        public bool DropStopColumn { get; set; }
     }
 
     /// <summary>

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/QueryAggregator.cs

@@ -155,12 +155,18 @@ internal string BuildFluxQuery(QueryableOptimizerSettings settings)
                 BuildOperator("from", "bucket", _bucketAssignment),
                 BuildRange(transforms),
                 BuildFilter(_filterByTags),
-                "pivot(rowKey:[\"_time\"], columnKey: [\"_field\"], valueColumn: \"_value\")",
-                "drop(columns: [\"_start\", \"_stop\", \"_measurement\"])",
-                settings.QueryMultipleTimeSeries ? "group()" : "",
-                BuildFilter(_filterByFields)
+                "pivot(rowKey:[\"_time\"], columnKey: [\"_field\"], valueColumn: \"_value\")"
             };
 
+            var drop = BuildDrop(settings);
+            if (!string.IsNullOrEmpty(drop))
+            {
+                parts.Add(drop);
+            }
+
+            parts.Add(settings.QueryMultipleTimeSeries ? "group()" : "");
+            parts.Add(BuildFilter(_filterByFields));
+
             // https://docs.influxdata.com/influxdb/cloud/reference/flux/stdlib/built-in/transformations/sort/
             foreach (var ((column, columnVariable, descending, descendingVariable), index) in _orders.Select((value, i) => (value, i)))
             {
@@ -203,6 +209,33 @@ internal string BuildFluxQuery(QueryableOptimizerSettings settings)
             return query.ToString();
         }
 
+        private string BuildDrop(QueryableOptimizerSettings settings)
+        {
+            var columns = new List<string>();
+
+            if (settings.DropStartColumn)
+            {
+                columns.Add("\"_start\"");
+            }
+
+            if (settings.DropStopColumn)
+            {
+                columns.Add("\"_stop\"");
+            }
+
+            if (settings.DropMeasurementColumn)
+            {
+                columns.Add("\"_measurement\"");
+            }
+
+            if (columns.Count == 0)
+            {
+                return null;
+            }
+
+            return $"drop(columns: [{string.Join(", ", columns)}])";
+        }
+
         private string BuildRange(List<string> transforms)
         {
             string rangeStartShift = null;

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.Linq/Internal/QueryVisitor.cs

@@ -75,7 +75,7 @@ public override void VisitWhereClause(WhereClause whereClause, QueryModel queryM
             var tagFilter = new List<IExpressionPart>();
             var fieldFilter = new List<IExpressionPart>();
 
-            // Map LINQ filter expresion to right place: range, tag filtering, field filtering
+            // Map LINQ filter expression to right place: range, tag filtering, field filtering
             foreach (var expression in expressions)
             {
                 switch (expression)
@@ -86,6 +86,7 @@ public override void VisitWhereClause(WhereClause whereClause, QueryModel queryM
                         break;
                     // Tag
                     case TagColumnName _:
+                    case MeasurementColumnName _:
                         tagFilter.Add(expression);
                         break;
                     // Field
@@ -187,7 +188,7 @@ private string ConcatExpression(IEnumerable<IExpressionPart> expressions)
             }).ToString();
         }
 
-                private void AddFilterByRange(List<IExpressionPart> rangeFilter)
+        private void AddFilterByRange(List<IExpressionPart> rangeFilter)
         {
             var rangeBinaryIndexes = Enumerable.Range(0, rangeFilter.Count)
                 .Where(i => rangeFilter[i] is BinaryOperator)

Client.Test/ItTasksApiTest.cs

@@ -527,9 +527,9 @@ public async Task Runs()
             Assert.IsNotEmpty(run.Id);
             Assert.AreEqual(task.Id, run.TaskID);
             Assert.AreEqual(Run.StatusEnum.Success, run.Status);
-            Assert.Greater(DateTime.Now, run.StartedAt);
-            Assert.Greater(DateTime.Now, run.FinishedAt);
-            Assert.Greater(DateTime.Now, run.ScheduledFor);
+            Assert.Greater(DateTime.UtcNow, run.StartedAt);
+            Assert.Greater(DateTime.UtcNow, run.FinishedAt);
+            Assert.Greater(DateTime.UtcNow, run.ScheduledFor);
             Assert.IsNull(run.RequestedAt);
 
             task = await _tasksApi.FindTaskByIdAsync(task.Id);