add error code

tf in select

refactor dataframe join

rename df join

src/main/scala/com/snowflake/snowpark/DataFrame.scala

@@ -561,18 +561,35 @@ class DataFrame private[snowpark] (
       "Provide at least one column expression for select(). " +
         s"This DataFrame has column names (${output.length}): " +
         s"${output.map(_.name).mkString(", ")}\n")
-
-    val resultDF = withPlan { Project(columns.map(_.named), plan) }
-    // do not rename back if this project contains internal alias.
-    // because no named duplicated if just renamed.
-    val hasInternalAlias: Boolean = columns.map(_.expr).exists {
-      case Alias(_, _, true) => true
-      case _ => false
-    }
-    if (hasInternalAlias) {
-      resultDF
-    } else {
-      renameBackIfDeduped(resultDF)
+    // todo: error message
+    val tf = columns.filter(_.expr.isInstanceOf[TableFunctionExpression])
+    tf.size match {
+      case 0 =>
+        val resultDF = withPlan {
+          Project(columns.map(_.named), plan)
+        }
+        // do not rename back if this project contains internal alias.
+        // because no named duplicated if just renamed.
+        val hasInternalAlias: Boolean = columns.map(_.expr).exists {
+          case Alias(_, _, true) => true
+          case _ => false
+        }
+        if (hasInternalAlias) {
+          resultDF
+        } else {
+          renameBackIfDeduped(resultDF)
+        }
+      case 1 =>
+        val base = this.join(tf.head)
+        val baseColumns = base.schema.map(field => base(field.name))
+        val inputDFColumnSize = this.schema.size
+        val tfColumns = baseColumns.splitAt(inputDFColumnSize)._2
+        val (beforeTf, afterTf) = columns.span(_ != tf.head)
+        val resultColumns = beforeTf ++ tfColumns ++ afterTf.tail
+        base.select(resultColumns)
+      case _ =>
+        // more than 1 TF
+        throw ErrorMessage.DF_MORE_THAN_ONE_TF_IN_SELECT()
     }
   }
 
@@ -1788,9 +1805,8 @@ class DataFrame private[snowpark] (
    *   object or an object that you create from the [[TableFunction]] class.
    * @param args A list of arguments to pass to the specified table function.
    */
-  def join(func: TableFunction, args: Seq[Column]): DataFrame = withPlan {
-    TableFunctionJoin(this.plan, func.call(args: _*), None)
-  }
+  def join(func: TableFunction, args: Seq[Column]): DataFrame =
+    joinTableFunction(func.call(args: _*), None)
 
   /**
    * Joins the current DataFrame with the output of the specified user-defined table
@@ -1822,12 +1838,10 @@ class DataFrame private[snowpark] (
       func: TableFunction,
       args: Seq[Column],
       partitionBy: Seq[Column],
-      orderBy: Seq[Column]): DataFrame = withPlan {
-    TableFunctionJoin(
-      this.plan,
+      orderBy: Seq[Column]): DataFrame =
+    joinTableFunction(
       func.call(args: _*),
       Some(Window.partitionBy(partitionBy: _*).orderBy(orderBy: _*).getWindowSpecDefinition))
-  }
 
   /**
    * Joins the current DataFrame with the output of the specified table function `func` that takes
@@ -1859,9 +1873,8 @@ class DataFrame private[snowpark] (
    *              Some functions, like `flatten`, have named parameters.
    *              Use this map to specify the parameter names and their corresponding values.
    */
-  def join(func: TableFunction, args: Map[String, Column]): DataFrame = withPlan {
-    TableFunctionJoin(this.plan, func.call(args), None)
-  }
+  def join(func: TableFunction, args: Map[String, Column]): DataFrame =
+    joinTableFunction(func.call(args), None)
 
   /**
    * Joins the current DataFrame with the output of the specified user-defined table function
@@ -1900,12 +1913,10 @@ class DataFrame private[snowpark] (
       func: TableFunction,
       args: Map[String, Column],
       partitionBy: Seq[Column],
-      orderBy: Seq[Column]): DataFrame = withPlan {
-    TableFunctionJoin(
-      this.plan,
+      orderBy: Seq[Column]): DataFrame =
+    joinTableFunction(
       func.call(args),
       Some(Window.partitionBy(partitionBy: _*).orderBy(orderBy: _*).getWindowSpecDefinition))
-  }
 
   /**
    * Joins the current DataFrame with the output of the specified table function `func`.
@@ -1929,9 +1940,8 @@ class DataFrame private[snowpark] (
    * @param func [[TableFunction]] object, which can be one of the values in the [[tableFunctions]]
    *             object or an object that you create from the [[TableFunction.apply()]].
    */
-  def join(func: Column): DataFrame = withPlan {
-    TableFunctionJoin(this.plan, getTableFunctionExpression(func), None)
-  }
+  def join(func: Column): DataFrame =
+    joinTableFunction(getTableFunctionExpression(func), None)
 
   /**
    * Joins the current DataFrame with the output of the specified user-defined table function
@@ -1951,11 +1961,30 @@ class DataFrame private[snowpark] (
    * @param partitionBy A list of columns partitioned by.
    * @param orderBy     A list of columns ordered by.
    */
-  def join(func: Column, partitionBy: Seq[Column], orderBy: Seq[Column]): DataFrame = withPlan {
-    TableFunctionJoin(
-      this.plan,
+  def join(func: Column, partitionBy: Seq[Column], orderBy: Seq[Column]): DataFrame =
+    joinTableFunction(
       getTableFunctionExpression(func),
       Some(Window.partitionBy(partitionBy: _*).orderBy(orderBy: _*).getWindowSpecDefinition))
+
+  private def joinTableFunction(
+      func: TableFunctionExpression,
+      partitionByOrderBy: Option[WindowSpecDefinition]): DataFrame = {
+    val originalResult = withPlan {
+      TableFunctionJoin(this.plan, func, partitionByOrderBy)
+    }
+    val resultSchema = originalResult.schema
+    val columnNames = resultSchema.map(_.name)
+    // duplicated names
+    val dup = columnNames.diff(columnNames.distinct).distinct
+    // guarantee no duplicated names in the result
+    if (dup.nonEmpty) {
+      val dfPrefix = DataFrame.generatePrefix('o')
+      val renamedDf =
+        this.select(this.output.map(_.name).map(aliasIfNeeded(this, _, dfPrefix, dup.toSet)))
+      renamedDf.joinTableFunction(func, partitionByOrderBy)
+    } else {
+      originalResult
+    }
   }
 
   /**

src/main/scala/com/snowflake/snowpark/internal/ErrorMessage.scala

@@ -68,6 +68,7 @@ private[snowpark] object ErrorMessage {
     "0128" -> "DataFrameWriter doesn't support to set option '%s' as '%s' in '%s' mode when writing to a %s.",
     "0129" -> "DataFrameWriter doesn't support mode '%s' when writing to a %s.",
     "0130" -> "Unsupported join operations, Dataframes can join with other Dataframes or TableFunctions only",
+    "0131" -> "At most one table function can be called inside select() function",
     // Begin to define UDF related messages
     "0200" -> "Incorrect number of arguments passed to the UDF: Expected: %d, Found: %d",
     "0201" -> "Attempted to call an unregistered UDF. You must register the UDF before calling it.",
@@ -244,6 +245,9 @@ private[snowpark] object ErrorMessage {
   def DF_JOIN_WITH_WRONG_ARGUMENT(): SnowparkClientException =
     createException("0130")
 
+  def DF_MORE_THAN_ONE_TF_IN_SELECT(): SnowparkClientException =
+    createException("0131")
+
   /*
    * 2NN: UDF error code
    */

src/test/scala/com/snowflake/snowpark/ErrorMessageSuite.scala

@@ -296,6 +296,14 @@ class ErrorMessageSuite extends FunSuite {
           " or TableFunctions only"))
   }
 
+  test("DF_MORE_THAN_ONE_TF_IN_SELECT") {
+    val ex = ErrorMessage.DF_MORE_THAN_ONE_TF_IN_SELECT()
+    assert(ex.telemetryMessage.equals(ErrorMessage.getMessage("0131")))
+    assert(
+      ex.message.startsWith("Error Code: 0131, Error message: " +
+        "At most one table function can be called inside select() function"))
+  }
+
   test("UDF_INCORRECT_ARGS_NUMBER") {
     val ex = ErrorMessage.UDF_INCORRECT_ARGS_NUMBER(1, 2)
     assert(ex.telemetryMessage.equals(ErrorMessage.getMessage("0200")))

src/test/scala/com/snowflake/snowpark_test/TableFunctionSuite.scala

@@ -337,4 +337,32 @@ class TableFunctionSuite extends TestData {
         .select("value"),
       Seq(Row("77"), Row("88")))
   }
+
+  test("table function in select") {
+    val df = Seq((1, "1,2"), (2, "3,4")).toDF("idx", "data")
+    // only tf
+    val result1 = df.select(tableFunctions.split_to_table(df("data"), ","))
+    assert(result1.schema.map(_.name) == Seq("SEQ", "INDEX", "VALUE"))
+    checkAnswer(result1, Seq(Row(1, 1, "1"), Row(1, 2, "2"), Row(2, 1, "3"), Row(2, 2, "4")))
+
+    // columns + tf
+    val result2 = df.select(df("idx"), tableFunctions.split_to_table(df("data"), ","))
+    assert(result2.schema.map(_.name) == Seq("IDX", "SEQ", "INDEX", "VALUE"))
+    checkAnswer(
+      result2,
+      Seq(Row(1, 1, 1, "1"), Row(1, 1, 2, "2"), Row(2, 2, 1, "3"), Row(2, 2, 2, "4")))
+
+    // columns + tf + columns
+    val result3 = df.select(df("idx"), tableFunctions.split_to_table(df("data"), ","), df("idx"))
+    assert(result3.schema.map(_.name) == Seq("IDX", "SEQ", "INDEX", "VALUE", "IDX"))
+    checkAnswer(
+      result3,
+      Seq(Row(1, 1, 1, "1", 1), Row(1, 1, 2, "2", 1), Row(2, 2, 1, "3", 2), Row(2, 2, 2, "4", 2)))
+
+    // tf + other express
+    val result4 = df.select(tableFunctions.split_to_table(df("data"), ","), df("idx") + 100)
+    checkAnswer(
+      result4,
+      Seq(Row(1, 1, "1", 101), Row(1, 2, "2", 101), Row(2, 1, "3", 102), Row(2, 2, "4", 102)))
+  }
 }