Migrate source XLS

A source migrate plugin, to allow us to use XLS and XLSX files as a migration source.

Requirements:

• Drupal 8
• PHPExcel library(>=1.8.1)
• Migrate module (>= 8.1)

Usage:

To use this plugin you have to:

• install PHPExcel library via Composer
• install this module via default installation process

Next point it's specifying a source plugin in your migration
and all it's params:

source:
  # Specify the plugin ID.
  plugin: xls
  # Define the path to the XLS source file.
  path: public://mySources/source.xls
  # Define unique key(s).
  keys:
    - id
  # Header row(to figure out which row is should be parsed as a column titles/headers).
  header_row: 1
  # Columns mapping:
  columns:
    -  My column name: my_column_name