Module org.jooq
Package org.jooq.impl

Interface QOM.SelectIsNull

All Superinterfaces:
Condition, QueryPart, Serializable
Enclosing class:

public static interface QOM.SelectIsNull extends Condition
  • Method Details

    • $field

      @NotNull default @NotNull Select<?> $field()
    • $arg1

      Select<?> $arg1()
    • $arg1

      @NotNull default Condition $arg1(Select<?> newArg1)
    • constructor

      @NotNull @NotNull Function1<? super Select<?>,​? extends Condition> constructor()
    • transform

      default <T> T transform(Function1<? super Select<?>,​? extends T> function)
    • $traverse

      default <T> T $traverse(Traverser<?,​T> traverser)
      Description copied from interface: QueryPart
      Traverser this QueryPart expression tree using a composable Traverser, producing a result.

      This offers a generic way to traverse expression trees to translate the tree to arbitrary other data structures. The simplest traversal would just count all the tree elements:

       int count = CUSTOMER.NAME.eq(1).$traverse(0, (i, p) -> i + 1);

      The same can be achieved by translating the JDK Collector API to the Traverser API using Traversers.collecting(Collector).


      Unlike a Collector, a Traverser is optimised for tree traversal, not stream traversal:

      • Is not designed for parallelism
      • It can Traverser.abort() traversal early when the result can be produced early (e.g. when running Traversers.containing(QueryPart), and a result has been found).
      • It can decide whether to Traverser.recurse() into a QueryPart subtree, or whether that is not necessary or even undesirable, e.g. to prevent entering new subquery scopes.
      • Unlike a Collector, which can use its Collector.accumulator() to accumulate each element only once, in tree traversal, it's desirable to be able to distinguish between accumulating an item Traverser.before() or Traverser.after() recursing into it. This is useful e.g. to wrap each tree node in XML opening and closing tags.
      Specified by:
      $traverse in interface QueryPart
    • $replace

      @NotNull default QueryPart $replace(Predicate<? super QueryPart> recurse, Function1<? super QueryPart,​? extends QueryPart> replacement)
      Description copied from interface: QueryPart
      Traverse a QueryPart hierarchy and recursively replace its elements by alternatives.
      Specified by:
      $replace in interface QueryPart
      recurse - A predicate to decide whether to recurse into a QueryPart subtree.
      replacement - The replacement function. Replacement continues recursively until the function returns null or its input for any given input.