Package org.apache.beam.sdk.schemas.utils

Class SelectHelpers

java.lang.Object
org.apache.beam.sdk.schemas.utils.SelectHelpers
public class SelectHelpers extends Object
Helper methods to select subrows out of rows.

  • Field Details

    • CONCAT_FIELD_NAMES

      public static final SerializableFunction<List<String>,String> CONCAT_FIELD_NAMES
      This policy keeps all levels of a name. Every field name in the path to a given field is concated with _ characters.

    • KEEP_NESTED_NAME

      public static final SerializableFunction<List<String>,String> KEEP_NESTED_NAME
      This policy keeps the raw nested field name. If two differently-nested fields have the same name, flattening will fail with this policy.

  • Constructor Details

    • SelectHelpers

      public SelectHelpers()

  • Method Details

    • getOutputSchema

      public static Schema getOutputSchema(Schema inputSchema, FieldAccessDescriptor fieldAccessDescriptor)
      Get the output schema resulting from selecting the given FieldAccessDescriptor from the given schema.

      Fields are always extracted and then stored in a new Row. For example, consider the following Java POJOs: 

      
  class UserEvent {
    String userId;
    String eventId;
    int eventType;
    Location location;
 }
 
      
 class Location {
   double latitude;
   double longitude;
 }

      If selecting just the location field, then the returned schema will wrap that of the singular field being selected; in this case the returned schema will be a Row containing a single Location field. If location.latitude is selected, then the returned Schema will be a Row containing a double latitude field.

      The same holds true when selecting from lists or maps. For example: 

      
 class EventList {
   List<UserEvent> events;
 }

      If selecting events.location.latitude, the returned schema will contain a single array of Row, where that Row contains a single double latitude field; it will not contain an array of double.

    • getRowSelectorOptimized

      public static RowSelector getRowSelectorOptimized(Schema inputSchema, FieldAccessDescriptor fieldAccessDescriptor)

    • getRowSelector

      public static RowSelector getRowSelector(Schema inputSchema, FieldAccessDescriptor fieldAccessDescriptor)

    • allLeavesDescriptor

      public static FieldAccessDescriptor allLeavesDescriptor(Schema schema, SerializableFunction<List<String>,String> nameFn)