Fixed for issue #89

Where a tool had two routes leading back  to the same parent nodes,
those nodes would be defined in the query more than once

Author: d4nt

Engine/NodeBase.cs

@@ -210,6 +210,11 @@ private static string BuildWithSql(IEnumerable<NodeBase> orderedUpstreamDependen
 
         internal virtual void FetchOrderedDependencies(IList<NodeBase> dependencies)
         {
+            if (dependencies.Contains(this))
+            {
+                dependencies.Remove(this);
+            }
+            
             dependencies.Insert(0, this);
         }
 

Tests/AppendTests.cs

@@ -7,6 +7,102 @@ namespace QueryTree.Engine.Tests
 {
     public class AppendTests
     {
+        private List<ITableInfo> DatabaseInfo
+		{
+			get
+			{
+				return new List<ITableInfo>()
+				{
+					new MockTableInfo()
+					{
+						DisplayName = "employees",
+						Columns = new List<IColumnInfo>()
+						{
+							new MockColumnInfo() { DataType = "int", Name = "ID" },
+							new MockColumnInfo() { DataType = "varchar", Name = "Name" },
+							new MockColumnInfo() { DataType = "int", Name = "department_id" }
+						}
+					},
+                    new MockTableInfo()
+					{
+						DisplayName = "departments",
+						Columns = new List<IColumnInfo>()
+						{
+							new MockColumnInfo() { DataType = "int", Name = "ID" },
+							new MockColumnInfo() { DataType = "varchar", Name = "Name" }
+						}
+					}
+				};
+			}
+		}
 
+        private string NodesJsonWithComplexAppend
+		{
+			get
+			{
+				return @"[
+                    {
+                        ""Id"": ""1"",
+                        ""Type"": ""Data Table"",
+                        ""Table"": ""employees""
+                    },
+                    {
+                        ""Id"": ""2"",
+                        ""Type"": ""Data Table"",
+                        ""Table"": ""departments""
+                    },
+                    {
+                        ""Id"": ""3"",
+                        ""Inputs"": [""1"",""2""],
+                        ""Type"": ""Join"",
+                        ""JoinType"": ""Inner"",
+                        ""Table1Column"": ""department_id"",
+                        ""Table2Column"": ""ID""
+                    },
+                    {
+                        ""Id"": ""4"",
+                        ""Inputs"": [""3""],
+                        ""Type"": ""Filter"",
+                        ""FilterColumnIndex"": 0,
+                        ""Operator"": ""EqualTo"",
+                        ""FilterValue1"": ""1""
+                    },
+                    {
+                        ""Id"": ""5"",
+                        ""Inputs"": [""3""],
+                        ""Type"": ""Filter"",
+                        ""FilterColumnIndex"": 0,
+                        ""Operator"": ""EqualTo"",
+                        ""FilterValue1"": ""2""
+                    },
+                    {
+                        ""Id"": ""6"",
+                        ""Inputs"": [""4"",""5""],
+                        ""Type"": ""Append"",
+                        ""IncludeUniqueColumns"": true
+                    }
+                ]";
+			}
+		}
+
+        [Fact]
+		public void TestMultipleRoutesToDataTablesDoesntDefineThemTwice()
+		{
+			var query = new Query(
+				DatabaseType.PostgreSQL,
+				NodesJsonWithComplexAppend,
+				DatabaseInfo);
+
+			var sql = query.GetSql("6");
+
+            // count how many times "node_1" is defined
+            int c = 0;
+            int i = -1;
+            while ((i = sql.IndexOf("node_1 AS", i+1)) >= 0)
+                c++;
+            
+            // The "node_1" datatable should only be defined once in the query
+			Assert.Equal(1, c);
+		}
     }
 }