format method

String format(Iterable<Map<String, Object?>> rows, [ Iterable<String>? columns ])

Formats the specified iterable of map rows as delimiter-separated values, returning a string.

This operation is the inverse of parse. Each row will be separated by a newline (\n), and each column within each row will be separated by the delimiter (such as a comma, ,). Values that contain either the delimiter, a double-quote (") or a newline will be escaped using double-quotes.

If columns is not specified, the list of column names that forms the header row is determined by the union of all properties on all objects in rows; the order of columns is the order in which they appear. If columns is specified, it is an iterable of strings representing the column names. For example:

final string = csvFormat(data, ["year", "make", "model", "length"]);

All fields on each row map will be coerced to strings. If the field value is null, the empty string is used. If the field value is a Date, the ECMAScript date-time string format (a subset of ISO 8601) is used: for example, dates at UTC midnight are formatted as YYYY-MM-DD. For more control over which and how fields are formatted, first map rows to an iterable of iterable of string, and then use formatRows.

Implementation

String format(Iterable<Map<String, Object?>> rows,
    [Iterable<String>? columns]) {
  columns ??= _inferColumns(rows);
  return [columns.map(formatValue).join(_delimiter)]
      .followedBy(_preformatBody(rows, columns))
      .join("\n");
}