io.cdap.wrangler.schema

Class DirectiveOutputSchemaGenerator

java.lang.Object

io.cdap.wrangler.schema.DirectiveOutputSchemaGenerator

public class DirectiveOutputSchemaGenerator
extends Object

This class can be used to generate the output schema for the output data of a directive. It maintains a map of output fields present across all output rows after applying a directive. This map is used to generate the schema if the directive does not return a custom output schema.

Constructor Summary

Constructors

Constructor and Description
DirectiveOutputSchemaGenerator(Directive directive, SchemaConverter schemaGenerator)

Method Summary

Modifier and Type	Method and Description
void	addNewOutputFields(List<Row> output) Method to add new fields from the given output to the map of fieldName --> value maintained for schema generation.
io.cdap.cdap.api.data.schema.Schema	getDirectiveOutputSchema(SchemaResolutionContext context) Method to get the output schema of the directive.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DirectiveOutputSchemaGenerator

public DirectiveOutputSchemaGenerator(Directive directive,
                                      SchemaConverter schemaGenerator)

Method Detail

addNewOutputFields

public void addNewOutputFields(List<Row> output)

Method to add new fields from the given output to the map of fieldName --> value maintained for schema generation. A value is added to the map only if it is absent (or) if the existing value is null and given value is non-null

Parameters:

output - list of output Rows after applying directive.

getDirectiveOutputSchema

public io.cdap.cdap.api.data.schema.Schema getDirectiveOutputSchema(SchemaResolutionContext context)
                                                             throws RecordConvertorException

Method to get the output schema of the directive. Returns a generated schema based on maintained map of fields only if directive does not return a custom output schema.

Parameters:

context - input Schema of the data before applying the directive

Returns:

Schema corresponding to the output data

Throws:

RecordConvertorException