Constructor Detail

• DerbyConcatFunction

  public DerbyConcatFunction()

Method Detail

• hasArguments

  public boolean hasArguments()

  Does this function have any arguments?

  Here we always return true

  Specified by:

  hasArguments in interface SQLFunction

  Returns:

  True if the function expects to have parameters; false otherwise.

• hasParenthesesIfNoArguments

  public boolean hasParenthesesIfNoArguments()

  If there are no arguments, are parentheses required?

  Here we always return true

  Specified by:

  hasParenthesesIfNoArguments in interface SQLFunction

  Returns:

  True if a no-arg call of this function requires parentheses.

• getReturnType

  public Type getReturnType(Type argumentType,
                   Mapping mapping)
                     throws QueryException

  The return type of the function. May be either a concrete type which is preset, or variable depending upon the type of the first function argument.

  Note, the 'firstArgumentType' parameter should match the one passed into SQLFunction.render(org.hibernate.type.Type, java.util.List, org.hibernate.engine.SessionFactoryImplementor)

  Here we always return Hibernate.STRING.

  Specified by:

  getReturnType in interface SQLFunction

  Parameters:

  argumentType - The type of the first argument

  mapping - The mapping source.

  Returns:

  The type to be expected as a return.

  Throws:

  QueryException - Indicates an issue resolving the return type.

• render

  public String render(Type argumentType,
              List args,
              SessionFactoryImplementor factory)
                throws QueryException

  Render the function call as SQL fragment.

  Note, the 'firstArgumentType' parameter should match the one passed into SQLFunction.getReturnType(org.hibernate.type.Type, org.hibernate.engine.Mapping)

  Here's the meat.. The whole reason we have a separate impl for this for Derby is to re-define this method. The logic here says that if not all the incoming args are dynamic parameters (i.e. ?) then we simply use the Derby concat operator (||) on the unchanged arg elements. However, if all the args are dynamic parameters, then we need to wrap the individual arg elements in cast function calls, use the concatenation operator on the cast returns, and then wrap that whole thing in a call to the Derby varchar function.

  Specified by:

  render in interface SQLFunction

  Parameters:

  argumentType - The type of the first argument

  args - The function arguments

  factory - The SessionFactory

  Returns:

  The rendered function call

  Throws:

  QueryException - Indicates a problem rendering the function call.