Column filter plugin for Embulk

A filter plugin for Embulk to filter out columns

Configuration

• columns: columns to retain (array of hash)
  • name: name of column (required)
  • src: src column name to be copied (optional, default is name)
  • default: default value used if input is null (optional)
  • type: type of the default value (required for default)
  • format: special option for timestamp column, specify the format of the default timestamp (string, default is default_timestamp_format)
  • timezone: special option for timestamp column, specify the timezone of the default timestamp (string, default is default_timezone)
• add_columns: columns to add (array of hash)
  • name: name of column (required)
  • src: src column name to be copied (either of src or default is required)
  • default: value of column (either of src or default is required)
  • type: type of the default value (required for default)
  • format: special option for timestamp column, specify the format of the default timestamp (string, default is default_timestamp_format)
  • timezone: special option for timestamp column, specify the timezone of the default timestamp (string, default is default_timezone)
• drop_columns: columns to drop (array of hash)
  • name: name of column (required)
• default_timestamp_format: default timestamp format for timestamp columns (string, default is %Y-%m-%d %H:%M:%S.%N %z)
• default_timezone: default timezone for timestamp columns (string, default is UTC)

Example (columns)

Say input.csv is as follows:

time,id,key,score
2015-07-13,0,Vqjht6YEUBsMPXmoW1iOGFROZF27pBzz0TUkOKeDXEY,1370
2015-07-13,1,VmjbjAA0tOoSEPv_vKAGMtD_0aXZji0abGe7_VXHmUQ,3962
2015-07-13,2,C40P5H1WcBx-aWFDJCI8th6QPEI2DOUgupt_gB8UutE,7323

filters:
  - type: column
    columns:
      - {name: time, default: "2015-07-13", format: "%Y-%m-%d"}
      - {name: id}
      - {name: key, default: "foo"}

reduces columns to only time, id, and key columns as:

2015-07-13,0,Vqjht6YEUBsMPXmoW1iOGFROZF27pBzz0TUkOKeDXEY
2015-07-13,1,VmjbjAA0tOoSEPv_vKAGMtD_0aXZji0abGe7_VXHmUQ
2015-07-13,2,C40P5H1WcBx-aWFDJCI8th6QPEI2DOUgupt_gB8UutE

Note that column types are automatically retrieved from input data (inputSchema).

Example (add_columns)

Say input.csv is as follows:

time,id,key,score
2015-07-13,0,Vqjht6YEUBsMPXmoW1iOGFROZF27pBzz0TUkOKeDXEY,1370
2015-07-13,1,VmjbjAA0tOoSEPv_vKAGMtD_0aXZji0abGe7_VXHmUQ,3962
2015-07-13,2,C40P5H1WcBx-aWFDJCI8th6QPEI2DOUgupt_gB8UutE,7323

filters:
  - type: column
    add_columns:
      - {name: d, type: timestamp, default: "2015-07-13", format: "%Y-%m-%d"}
      - {name: copy_id, src: id}

add d column, and copy_id column which is a copy of id column as:

2015-07-13,0,Vqjht6YEUBsMPXmoW1iOGFROZF27pBzz0TUkOKeDXEY,1370,2015-07-13,0
2015-07-13,1,VmjbjAA0tOoSEPv_vKAGMtD_0aXZji0abGe7_VXHmUQ,3962,2015-07-13,1
2015-07-13,2,C40P5H1WcBx-aWFDJCI8th6QPEI2DOUgupt_gB8UutE,7323,2015-07,13,2

Example (drop_columns)

Say input.csv is as follows:

time,id,key,score
2015-07-13,0,Vqjht6YEUBsMPXmoW1iOGFROZF27pBzz0TUkOKeDXEY,1370
2015-07-13,1,VmjbjAA0tOoSEPv_vKAGMtD_0aXZji0abGe7_VXHmUQ,3962
2015-07-13,2,C40P5H1WcBx-aWFDJCI8th6QPEI2DOUgupt_gB8UutE,7323

filters:
  - type: column
    drop_columns:
      - {name: time}
      - {name: id}

drop time and id columns as:

Vqjht6YEUBsMPXmoW1iOGFROZF27pBzz0TUkOKeDXEY,1370
VmjbjAA0tOoSEPv_vKAGMtD_0aXZji0abGe7_VXHmUQ,3962
C40P5H1WcBx-aWFDJCI8th6QPEI2DOUgupt_gB8UutE,7323

JSONPath (like) name

For type: json column, you can specify JSONPath for column's name as:

$.payload.key1
$.payload.array[0]
$.payload.array[*]

EXAMPLE:

• example/columns.yml
• example/add_columns.yml
• example/drop_columns.yml

NOTE:

• JSONPath syntax is not fully supported
• Embulk's type: json cannot have timestamp column, so type: timesatmp for add_columns or columns with default is not available
• src (to rename or copy columns) for add_columns or columns is only partially supported yet
  • the json path directory must be same, for example, {name: $.foo.copy, src: $foo.bar} works, but {name: $foo.copy, src: $.bar.baz} does not work

ToDo

• Write test

Development

Run example:

$ ./gradlew classpath
$ embulk preview -I lib example/example.yml

Run test:

$ ./gradlew test

Run test with coverage reports:

$ ./gradlew test jacocoTestReport

open build/reports/jacoco/test/html/index.html

Run checkstyle and findbugs:

$ ./gradlew check

Run only checkstyle:

$ ./gradlew checkstyleMain
$ ./gradlew checkstyleTest

Run only findbugs:

$ ./gradlew findbugsMain
$ ./gradlew findbugsTest

Release gem:

$ ./gradlew gemPush