Insert filter plugin for Embulk

Embulk filter plugin that inserts column(s) at any position (e.g., the top/bottom of the columns, before/after the specified column name)

• Plugin type: filter

Either "column" or "columns" is required for specifying inserted column(s).

• column: associative array that contains only one key-value pair (key means a column name, value means a constant value in the column)
• columns: List of the associative arrays

The "column" associate array can contain following optional configuration.

• as: type of the constant vaule in the column, i.e. boolean, long, double, string, timestamp or json(string, default: string)

Any of the following configurations is required for specifying a position where new columns are inserted.

• at: "top", "head", "bottom", "tail" or index number where the new column(s) is/are inserted (string)
• before: column name that comes before the new column(s) (string)
• after: column name that comes after the new column(s) (string)

If none of the configurations is specified, the new columns are inserted at the bottom of the existing columns.

Example 1: Insert "host_name" column at the top of the columns

filters:
  - { type: insert, column: { host_name: host01 }, at: top }

Example 2: Insert "host_name" column at the bottom of the columns

filters:
  - { type: insert, column: { host_name: host01 }, at: bottom }

Example 3: Insert "host_name" column after second column

filters:
  - { type: insert, column: { host_name: host01 }, at: 2 }

Example 4: Insert "service_name" column before "host_name" column

filters:
  - { type: insert, column: { service_name: service01 }, before: host_name }

Example 5: Insert "service_name" column after "host_name" column

filters:
  - { type: insert, column: { service_name: service01 }, after: host_name }

Example 6: Insert "user_id" column as integer at the bottom of the columns

filters:
  - { type: insert, column: { user_id: 1234567, as: long } }

Example 7: Insert multiple columns in a row at the bottom of the columns

filters:
  - type: insert
    columns:
      - host_name: host01
      - service_name: service01

Example 8: Combination of the above examples

filters:
  - type: insert
    columns:
      - service_name: service01
      - { user_id: 1234567, as: long }
    after: host_name

$ rake