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Add Column

Adds a new column with values to an existing DataTable. This node is useful for extending your table structure and populating it with data in a single operation.

Common Properties​

  • Name - The custom name of the node.
  • Color - The custom color of the node.
  • Delay Before (sec) - Waits in seconds before executing the node.
  • Delay After (sec) - Waits in seconds after executing node.
  • Continue On Error - Automation will continue regardless of any error. The default value is false.
info

If the ContinueOnError property is true, no error is caught when the project is executed, even if a Catch node is used.

Input​

  • Table - DataTable to add the column to
  • Column Name - Name of the new column to add
  • Values - Array of values for the new column

Output​

  • Table - Updated DataTable with the new column and values

Behavior​

The node behaves differently based on whether the table already has rows:

  • Table has existing rows: The values array is matched to existing rows by index. The length of values should match the number of existing rows.
  • Table is empty: New rows are created automatically, one for each value in the array.

Example Usage​

Adding a Column to an Empty Table​

// Start with an empty table that has columns: ["Name", "Age"]
var table = /* from Create DataTable */;

// Add a new column with values
var columnName = "Email";
var values = ["john@example.com", "jane@example.com", "bob@example.com"];

// Result: Table with 3 rows and 3 columns
// Row 0: Name="", Age="", Email="john@example.com"
// Row 1: Name="", Age="", Email="jane@example.com"
// Row 2: Name="", Age="", Email="bob@example.com"

Adding a Column to a Populated Table​

// Table already has 3 rows with columns: ["Name", "Age"]
// Row 0: Name="John", Age=30
// Row 1: Name="Jane", Age=25
// Row 2: Name="Bob", Age=35

var columnName = "Salary";
var values = [50000, 55000, 60000];

// Result: Table with 3 rows and 3 columns
// Row 0: Name="John", Age=30, Salary=50000
// Row 1: Name="Jane", Age=25, Salary=55000
// Row 2: Name="Bob", Age=35, Salary=60000

Adding Calculated Values​

// Add a column with calculated values from another source
var prices = [10.50, 20.00, 15.75];
var quantities = [5, 3, 10];

// Calculate totals
var totals = [];
for (var i = 0; i < prices.length; i++) {
    totals.push(prices[i] * quantities[i]);
}

// Add as a new column
var columnName = "Total";
// totals = [52.50, 60.00, 157.50]

Tips​

  • Ensure the values array length matches the number of rows if the table is already populated
  • Column names must be unique within the table
  • Values can be of any type (strings, numbers, booleans, objects)
  • This node is efficient for adding columns with pre-computed values
  • For adding empty columns, use a values array filled with empty strings or null values

Common Errors​

Empty Table Error​

Error: Table cannot be empty. Please provide a valid DataTable.

Solution: Ensure you're passing a valid DataTable object from a previous node (e.g., Create DataTable, Read CSV).

Empty Column Name Error​

Error: Column name cannot be empty. Please provide a valid column name.

Solution: Provide a non-empty string for the column name.

// Wrong
var columnName = "";

// Correct
var columnName = "Status";

Empty Values Error​

Error: Values cannot be empty. Please provide at least one value for the column.

Solution: Ensure the values array contains at least one element.

// Wrong
var values = [];

// Correct
var values = ["Active"];

Value Count Mismatch​

Error: Index out of bounds when values.length < existing row count

Solution: Ensure the values array has enough elements to match existing rows.

// If table has 5 rows, but only 3 values provided
// This will cause an error

// Correct approach:
var rowCount = 5; // Know your table size
var values = new Array(rowCount).fill("DefaultValue");

See Also​