Value Mapper Transformation (Deprecated)

Note: Datasets and the Value Mapper Transformation are deprecated and will be removed in CDAP 7.0.0.

The Value Mapper is a transformation plugin that maps string values of a field in the input record to a mapping value using a mapping dataset.

Mappings for the values are usually stored in a key-value dataset. The Value Mapper transformation provides a simple method for manipulating input data, both a field and its values, using a mapping.

Use Case

One use is to replace language codes in the input record field with an appropriate language description:

 **Source field name:** language_code
 **Target field name:** language_desc
 **Mappings, source to target:** DE/German, ES/Spanish, EN/English

This will replace the source column language_code with the target column language_desc, replacing values found in the source field using the mappings "DE" to "German", "ES" to "Spanish", and so on.

Configuration

Property	Macro Enabled?	Description

Property

Macro Enabled?

Description

Mapping

No

Required. A comma-separated list that defines the mapping of a source field to a target field and the mapping table name for looking up values. Contains three properties separated by a colon (":") as the source field, the mapping table name, and the target field:

<source-field>:<mapping-table-name>:<target-field>

Note: Source field supports only STRING types.

Defaults

No

Required. A comma-separated list that contains key-value pairs of a source field and its default value for cases where the source field value is either null or empty or if the mapping key-value is not present. If a default value has not been provided, the source field value will be mapped to the target field. Only STRING NULLABLE type values are accepted.

Example: <source field>:<defaultValue>

Output Schema

No

Required. The output schema for the data.

Example

As an example, take employee details as input data through a stream and then apply the Value Mapper transformation on the designation field in the input data.

Property	Value

Property	Value
Mapping	`designation:designationLookupTableName:designationName`
Defaults	`designation:DefaultDesignation`

If the transformation receives as an input record:

First Row:

field name	type	value

field name	type	value
id	string	“1234”
name	string	“John”
salary	int	9000
designation	string	“2”

Second Row:

field name	type	value

field name	type	value
id	string	“1967”
name	string	“Kelly”
salary	int	5000
designation	string	“5”

with this as the mapping dataset, designationLookupTableName:

key	value

key	value
“1”	“SE”
“2”	“SSE”
“3”	“ML”

After transformation by the ValueMapper plugin, the output will have this structure and contents, with the designation column replaced by the designationName column, using values looked up from the mapping database and default key-value pair:

First Row:

field name	type	value

field name	type	value
id	string	“1234”
name	string	“John”
salary	int	9000
designationName	string	“SSE”

Second Row:

field name	type	value

field name	type	value
id	string	“1967”
name	string	“Kelly”
salary	int	5000
designationName	string	“DefaultDesignation”