Package guru.mikelue.jdut.datagrain

Class DataRow.Builder

  • Enclosing class:
    DataRow
    public class DataRow.Builder
extends Object
    Used with DataRow.build(Consumer<DataRow.Builder>).

    Infinite recursion while using Supplier for value of field

    In following code snippet, the builder will set-up a field which cause infinite recursion while getting data: 
    
 builder -> builder.fieldOfValueSupplier(
     "ct_1", () -> 30 + builder.getDataSupplier("ct_1").get().get()
 )
    Since the lazy evaluation of lambda expression, the new lambda expression of "ct_1" would be a self-reference to builder.
    Instead, you should keep "the old instance of lambda expression": 
    
 builder -> {
     final Supplier<Integer> oldSupplier = builder.getDataSupplier("ct_1").get();
     builder.fieldOfValueSupplier("ct_1", () -> 30 + oldSupplier.get());
 }

    • Method Detail

      • tableSchema

        public DataRow.Builder tableSchema​(SchemaTable newTableSchema)
        Sets the table schema.
        Parameters:
        newTableSchema - The table schema
        Returns:
        cascading self

      • fieldOfValue

        public <T> DataRow.Builder fieldOfValue​(String columnName,
                                        T value)
        Sets value of a field.
        Type Parameters:
        T - The type of value
        Parameters:
        columnName - The name of column
        value - The value instance
        Returns:
        cascading self

      • fieldOfValueSupplier

        public <T> DataRow.Builder fieldOfValueSupplier​(String columnName,
                                                Supplier<T> valueSupplier)
        Sets value supplier of a field.
        Type Parameters:
        T - The type of value
        Parameters:
        columnName - The name of column
        valueSupplier - The value instance
        Returns:
        cascading self

      • getValidated

        public boolean getValidated()
        Whether the data row is validated or not.
        Returns:
        true if validated

      • getTableName

        public String getTableName()
        Gets name of table.
        Returns:
        the name of table
        See Also:
        getTable()

      • getData

        public <T> Optional<T> getData​(String columnName)
        Gets value of data.
        Type Parameters:
        T - The type of data
        Parameters:
        columnName - The name of column
        Returns:
        empty option if the column is not existing or the value is empty

      • getDataSupplier

        public <T> Optional<Supplier<T>> getDataSupplier​(String columnName)
        Gets supplier of data.

        Note: be careful of lazy building, which may cause infinite recursion

        Following code will cause infinite recursion 
        
 Supplier<Integer> wrappedSupplier = () -> 20 + builder.<Integer>getDataSupplier("ct_1").get().get();
 builder.fieldOfValueSupplier("col_1", wrappedSupplier);
        Instead, you should: 
        
 // Keep the reference of supplier in current lambda of builder
 Supplier<Integer> sourceSupplier = builder.<Integer>getDataSupplier("ct_1").get();
 Supplier<Integer> wrappedSupplier = () -> 20 + sourceSupplier.get();

 builder.fieldOfValueSupplier("col_1", wrappedSupplier);
        Type Parameters:
        T - The type of data for the supplier
        Parameters:
        columnName - The name of column
        Returns:
        empty option if the column is not existing or the value supplier is empty

      • getDataField

        public <T> Optional<DataField<T>> getDataField​(String columnName)
        Gets field of data.
        Type Parameters:
        T - The data type of field
        Parameters:
        columnName - The name of column
        Returns:
        empty option if the column is not existing

      • getStreamOfFields

        public Stream<DataField<?>> getStreamOfFields()
        Gets the fields as Stream.
        Returns:
        The data fields as stream