String overloads for decay function fields

Author: gmarz

src/Nest/DSL/Query/Functions/ExpFunction.cs

@@ -21,5 +21,14 @@ public ExpFunction(Expression<Func<T, object>> objectPath, Action<FunctionScoreD
 			descriptorBuilder(descriptor);
 			_ExpDescriptor[objectPath] = descriptor;
 		}
+
+		public ExpFunction(string field, Action<FunctionScoreDecayFieldDescriptor> descriptorBuilder)
+		{
+			_ExpDescriptor = new Dictionary<PropertyPathMarker, FunctionScoreDecayFieldDescriptor>();
+
+			var descriptor = new FunctionScoreDecayFieldDescriptor();
+			descriptorBuilder(descriptor);
+			_ExpDescriptor[field] = descriptor;
+		}
 	}
 }

src/Nest/DSL/Query/Functions/FunctionScoreFunctionsDescriptor.cs

@@ -16,20 +16,41 @@ public FunctionScoreFunctionsDescriptor()
 			this._Functions = new List<FunctionScoreFunction<T>>();
 		}
 
+		public FunctionScoreFunction<T> Gauss(string field, Action<FunctionScoreDecayFieldDescriptor> db)
+		{
+			var fn = new GaussFunction<T>(field, db);
+			this._Functions.Add(fn);
+			return fn;
+		}
+
 		public FunctionScoreFunction<T> Gauss(Expression<Func<T, object>> objectPath, Action<FunctionScoreDecayFieldDescriptor> db)
 		{
 			var fn = new GaussFunction<T>(objectPath, db);
 			this._Functions.Add(fn);
 			return fn;
 		}
 
+		public FunctionScoreFunction<T> Linear(string field, Action<FunctionScoreDecayFieldDescriptor> db)
+		{
+			var fn = new LinearFunction<T>(field, db);
+			this._Functions.Add(fn);
+			return fn;
+		}
+
 		public FunctionScoreFunction<T> Linear(Expression<Func<T, object>> objectPath, Action<FunctionScoreDecayFieldDescriptor> db)
 		{
 			var fn = new LinearFunction<T>(objectPath, db);
 			this._Functions.Add(fn);
 			return fn;
 		}
 
+		public FunctionScoreFunction<T> Exp(string field, Action<FunctionScoreDecayFieldDescriptor> db)
+		{
+			var fn = new ExpFunction<T>(field, db);
+			this._Functions.Add(fn);
+			return fn;
+		}
+
 		public FunctionScoreFunction<T> Exp(Expression<Func<T, object>> objectPath, Action<FunctionScoreDecayFieldDescriptor> db)
 		{
 			var fn = new ExpFunction<T>(objectPath, db);

src/Nest/DSL/Query/Functions/GaussFunction.cs

@@ -21,5 +21,14 @@ public GaussFunction(Expression<Func<T, object>> objectPath, Action<FunctionScor
 			descriptorBuilder(descriptor);
 			_GaussDescriptor[objectPath] = descriptor;
 		}
+
+		public GaussFunction(string field, Action<FunctionScoreDecayFieldDescriptor> descriptorBuilder)
+		{
+			_GaussDescriptor = new Dictionary<PropertyPathMarker, FunctionScoreDecayFieldDescriptor>();
+
+			var descriptor = new FunctionScoreDecayFieldDescriptor();
+			descriptorBuilder(descriptor);
+			_GaussDescriptor[field] = descriptor;
+		}
 	}
 }

src/Nest/DSL/Query/Functions/LinearFunction.cs

@@ -21,5 +21,14 @@ public LinearFunction(Expression<Func<T, object>> objectPath, Action<FunctionSco
 			descriptorBuilder(descriptor);
 			_LinearDescriptor[objectPath] = descriptor;
 		}
+
+		public LinearFunction(string field, Action<FunctionScoreDecayFieldDescriptor> descriptorBuilder)
+		{
+			_LinearDescriptor = new Dictionary<PropertyPathMarker, FunctionScoreDecayFieldDescriptor>();
+
+			var descriptor = new FunctionScoreDecayFieldDescriptor();
+			descriptorBuilder(descriptor);
+			_LinearDescriptor[field] = descriptor;
+		}
 	}
 }

src/Tests/Nest.Tests.Unit/Search/Sorting/FunctionScoreTests.cs

@@ -169,7 +169,7 @@ public void TestDecayFunctionWithFilter()
 			var s = new SearchDescriptor<ElasticsearchProject>().Query(
 				q => q.FunctionScore(
 					fs => fs.Functions(
-						f => f.Gauss(p => p.FloatValue, g => g.Origin("5").Scale("0.1"))
+						f => f.Gauss("floatValue", g => g.Origin("5").Scale("0.1"))
 							  .Filter(gf => gf.Term("term1", "termValue")
 							)
 						)