Add to string expression (#221)

koralium · Dec 22, 2023 · 2a4ad87 · 2a4ad87
1 parent a8f6cf8
commit 2a4ad87
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Showing 4 changed files with 51 additions and 0 deletions.
diff --git a/src/FlowtideDotNet.Core/Compute/Internal/BuiltInStringFunctions.cs b/src/FlowtideDotNet.Core/Compute/Internal/BuiltInStringFunctions.cs
@@ -50,6 +50,16 @@ public static void AddStringFunctions(FunctionsRegister functionsRegister)
             functionsRegister.RegisterScalarFunctionWithExpression(FunctionsString.Uri, FunctionsString.Trim, (x) => TrimImplementation(x));
             functionsRegister.RegisterScalarFunctionWithExpression(FunctionsString.Uri, FunctionsString.LTrim, (x) => LTrimImplementation(x));
             functionsRegister.RegisterScalarFunctionWithExpression(FunctionsString.Uri, FunctionsString.RTrim, (x) => RTrimImplementation(x));
+            functionsRegister.RegisterScalarFunctionWithExpression(FunctionsString.Uri, FunctionsString.To_String, (x) => ToStringImplementation(x));
+        }
+
+        private static FlxValue ToStringImplementation(in FlxValue val)
+        {
+            if (val.IsNull)
+            {
+                return NullValue;
+            }
+            return FlxValue.FromBytes(FlexBuffer.SingleValue(FlxValueStringFunctions.ToString(val)));
         }
 
         private static FlxValue LowerImplementation(in FlxValue val)

diff --git a/src/FlowtideDotNet.Substrait/FunctionExtensions/FunctionsString.cs b/src/FlowtideDotNet.Substrait/FunctionExtensions/FunctionsString.cs
@@ -27,5 +27,6 @@ public static class FunctionsString
         public const string Trim = "trim";
         public const string LTrim = "ltrim";
         public const string RTrim = "rtrim";
+        public const string To_String = "to_string";
     }
 }
diff --git a/src/FlowtideDotNet.Substrait/Sql/Internal/BuiltInSqlFunctions.cs b/src/FlowtideDotNet.Substrait/Sql/Internal/BuiltInSqlFunctions.cs
@@ -263,6 +263,28 @@ public static void AddBuiltInFunctions(SqlFunctionRegister sqlFunctionRegister)
                 }
             });
 
+            sqlFunctionRegister.RegisterScalarFunction("to_string", (f, visitor, emitData) =>
+            {
+                if (f.Args == null || f.Args.Count != 1)
+                {
+                    throw new InvalidOperationException("to_string must have exactly one argument");
+                }
+                if (f.Args[0] is FunctionArg.Unnamed unnamed && unnamed.FunctionArgExpression is FunctionArgExpression.FunctionExpression funcExpr)
+                {
+                    var expr = visitor.Visit(funcExpr.Expression, emitData);
+                    return new ScalarFunction()
+                    {
+                        ExtensionUri = FunctionsString.Uri,
+                        ExtensionName = FunctionsString.To_String,
+                        Arguments = new List<Expressions.Expression>() { expr.Expr }
+                    };
+                }
+                else
+                {
+                    throw new NotImplementedException("to_string does not support the input parameter");
+                }
+            });
+
             sqlFunctionRegister.RegisterScalarFunction("guid", (f, visitor, emitData) =>
             {
                 if (f.Args == null || f.Args.Count != 1)

diff --git a/tests/FlowtideDotNet.AcceptanceTests/DatetimeFunctionTests.cs b/tests/FlowtideDotNet.AcceptanceTests/DatetimeFunctionTests.cs
@@ -123,5 +123,23 @@ FROM buffered
             var rows2 = GetActualRows();
             // This test only validates that it can run for now
         }
+
+        [Fact]
+        public async Task ToStringTest()
+        {
+            GenerateData();
+            await StartStream(@"
+            INSERT INTO output
+            SELECT
+                to_string(orderkey) as orderkey
+            FROM Orders
+            ");
+            await WaitForUpdate();
+            AssertCurrentDataEqual(
+                Orders.Select(o => new {
+                    OrderKey = o.OrderKey.ToString()
+                })
+                );
+        }
     }
 }