CSHARP-1237: added ToString on FindFluent.

Author: craiggwilson

src/MongoDB.Driver.Tests/FindFluentTests.cs

@@ -13,10 +13,12 @@
 * limitations under the License.
 */
 
+using System;
 using System.Threading;
 using System.Threading.Tasks;
 using FluentAssertions;
 using MongoDB.Bson;
+using MongoDB.Bson.Serialization;
 using NSubstitute;
 using NUnit.Framework;
 
@@ -40,10 +42,44 @@ public void CountAsync_should_not_throw_a_null_reference_exception()
                 Arg.Any<CancellationToken>());
         }
 
+        [Test]
+        public void ToString_should_return_the_correct_string()
+        {
+            var subject = CreateSubject();
+            subject.Filter = new BsonDocument("Age", 20);
+            subject.Options.Comment = "awesome";
+            subject.Options.MaxTime = TimeSpan.FromSeconds(2);
+            subject.Options.Modifiers = new BsonDocument
+            {
+                { "$explain", true },
+                { "$hint", "ix_1" }
+            };
+
+            var find = subject
+                .SortBy(x => x.LastName)
+                .ThenByDescending(x => x.FirstName)
+                .Skip(2)
+                .Limit(10)
+                .Project(x => x.FirstName + " " + x.LastName);
+
+            var str = find.ToString();
+
+            str.Should().Be(
+                "find({ \"Age\" : 20 }, { \"FirstName\" : 1, \"LastName\" : 1, \"_id\" : 0 })" +
+                ".sort({ \"LastName\" : 1, \"FirstName\" : -1 })" +
+                ".skip(2)" +
+                ".limit(10)" +
+                ".maxTime(2000)" +
+                "._addSpecial(\"$comment\", \"awesome\")" +
+                "._addSpecial(\"$explain\", true)" +
+                "._addSpecial(\"$hint\", \"ix_1\")");
+        }
+
         private IFindFluent<Person, Person> CreateSubject()
         {
             var settings = new MongoCollectionSettings();
             _collection = Substitute.For<IMongoCollection<Person>>();
+            _collection.DocumentSerializer.Returns(BsonSerializer.SerializerRegistry.GetSerializer<Person>());
             _collection.Settings.Returns(settings);
             var options = new FindOptions<Person, Person>();
             var subject = new FindFluent<Person, Person>(_collection, new BsonDocument(), options);

src/MongoDB.Driver/FindFluent.cs

@@ -13,9 +13,12 @@
 * limitations under the License.
 */
 
+using System;
+using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
 using MongoDB.Bson;
+using MongoDB.Bson.Serialization;
 using MongoDB.Driver.Core.Misc;
 
 namespace MongoDB.Driver
@@ -107,5 +110,73 @@ public override IFindFluent<TDocument, TProjection> Sort(SortDefinition<TDocumen
         {
             return _collection.FindAsync(_filter, _options, cancellationToken);
         }
+
+
+        public override string ToString()
+        {
+            var sb = new StringBuilder("find(");
+            var renderedFilter = Render(_filter.Render);
+            sb.Append(renderedFilter.ToString());
+
+            if (_options.Projection != null)
+            {
+                var renderedProjection = Render(_options.Projection.Render);
+                if (renderedProjection.Document != null)
+                {
+                    sb.Append(", " + renderedProjection.Document.ToString());
+                }
+            }
+            sb.Append(")");
+
+            if (_options.Sort != null)
+            {
+                var renderedSort = Render(_options.Sort.Render);
+                sb.Append(".sort(" + renderedSort.ToString() + ")");
+            }
+
+            if (_options.Skip.HasValue)
+            {
+                sb.Append(".skip(" + _options.Skip.Value.ToString() + ")");
+            }
+
+            if (_options.Limit.HasValue)
+            {
+                sb.Append(".limit(" + _options.Limit.Value.ToString() + ")");
+            }
+
+            if (_options.MaxTime != null)
+            {
+                sb.Append(".maxTime(" + _options.MaxTime.Value.TotalMilliseconds + ")");
+            }
+
+            if (_options.Comment != null)
+            {
+                sb.Append("._addSpecial(\"$comment\", \"" + _options.Comment + "\")");
+            }
+
+            if (_options.Modifiers != null)
+            {
+                foreach (var modifier in _options.Modifiers)
+                {
+                    sb.Append("._addSpecial(\"" + modifier.Name + "\", ");
+                    if (modifier.Value.BsonType == BsonType.String)
+                    {
+                        sb.Append("\"" + modifier.Value.ToString() + "\"");
+                    }
+                    else
+                    {
+                        sb.Append(modifier.Value.ToString());
+                    }
+                    sb.Append(")");
+                }
+            }
+
+            return sb.ToString();
+        }
+
+        private TRendered Render<TRendered>(Func<IBsonSerializer<TDocument>, IBsonSerializerRegistry, TRendered> renderer)
+        {
+            return renderer(_collection.DocumentSerializer, _collection.Settings.SerializerRegistry);
+        }
     }
 }