Add Sample operation support, fixes #109

rethinkdb-net-test/Integration/ManyObjectTests.cs

@@ -105,6 +105,34 @@ public void ReuseSynchronousEnumerable()
                 Assert.That(count, Is.EqualTo(1005));
             }
         }
+
+        [Test]
+        public void Sample()
+        {
+            var query = testTable.Sample(10);
+
+            int count = 0;
+            HashSet<string> firstRunIds = new HashSet<string>();
+            foreach (var o in connection.Run(query))
+            {
+                firstRunIds.Add(o.Id);
+                count += 1;
+            }
+            Assert.That(count, Is.EqualTo(10));
+
+            HashSet<string> secondRunIds = new HashSet<string>();
+            foreach (var o in connection.Run(query))
+            {
+                secondRunIds.Add(o.Id);
+                count += 1;
+            }
+            Assert.That(count, Is.EqualTo(20));
+
+            // Two random sets of ten objects shouldn't have a lot of the same objects, if any; otherwise our Sample
+            // query might not be doing quite what we expect...
+            firstRunIds.IntersectWith(secondRunIds);
+            Assert.That(firstRunIds.Count, Is.LessThan(5));
+        }
     }
 }
 

rethinkdb-net/Query.cs

@@ -320,6 +320,11 @@ public static ISequenceQuery<Tuple<TGroupKeyType, TReductionType>> GroupBy<TObje
             return new GroupByQuery<TObject, TReductionType, TGroupKeyType>(sequenceQuery, reductionObject, groupKeyConstructor);
         }
 
+        public static ISequenceQuery<T> Sample<T>(this ISequenceQuery<T> target, int count)
+        {
+            return new SampleQuery<T>(target, count);
+        }
+
         #endregion
         #region Prebuilt GroupBy reductions
 

rethinkdb-net/QueryTerm/SampleQuery.cs

@@ -0,0 +1,38 @@
+using RethinkDb.Spec;
+using System;
+
+namespace RethinkDb.QueryTerm
+{
+    public class SampleQuery<T> : ISequenceQuery<T>
+    {
+        private readonly ISequenceQuery<T> sequenceQuery;
+        private readonly int number;
+
+        public SampleQuery(ISequenceQuery<T> sequenceQuery, int number)
+        {
+            this.sequenceQuery = sequenceQuery;
+            this.number = number;
+        }
+
+        public Term GenerateTerm(IDatumConverterFactory datumConverterFactory)
+        {
+            var sampleTerm = new Term()
+            {
+                type = Term.TermType.SAMPLE,
+            };
+            sampleTerm.args.Add(sequenceQuery.GenerateTerm(datumConverterFactory));
+            sampleTerm.args.Add(
+                new Term()
+                {
+                    type = Term.TermType.DATUM,
+                    datum = new Datum()
+                    {
+                        type = Datum.DatumType.R_NUM,
+                        r_num = number,
+                    }
+                }
+            );
+            return sampleTerm;
+        }
+    }
+}

rethinkdb-net/rethinkdb-net.csproj

@@ -156,6 +156,7 @@
     <Compile Include="DatumConverters\AbstractDatumConverterFactory.cs" />
     <Compile Include="DatumConverters\AbstractValueTypeDatumConverter.cs" />
     <Compile Include="DatumConverters\AbstractReferenceTypeDatumConverter.cs" />
+    <Compile Include="QueryTerm\SampleQuery.cs" />
   </ItemGroup>
   <ItemGroup>
     <None Include="packages.config" />