Developing Apama Applications > Developing Apama Applications in EPL > Using Correlator Plug-ins in EPL > Using the Payload Extraction plug-in > The direct-access functions > Parameters for secondary direct-access functions
Parameters for secondary direct-access functions
The parameters used by the sencondary direct-access function differ from those used by the primary functions as described in the following table:
Parameter
Description
default_nonExistent
The value to return if the field specified in field_name does not exist. The type of this parameter depends on the particular method.
default_empty
The value to return if the field specified in field_name has no value (is empty or null). The type of this parameter depends on the particular method.
default_invalid
The value to return if the field specified in field_name cannot be cast to the type requested or is otherwise invalid (e.g. contains binary escape codes). The type of this parameter depends on the particular method. Note that all types can be cast to a string, however, the opposite might not be possible. For example a string can be only be successfully cast to a float if it contains a valid float number, e.g. 1.0.
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