Query Conditions

DDS_QueryCondition and associated elements More...

Data Structures
struct	DDS_QueryConditionParams
	<<extension>> Input parameters for DDS_DataReader_create_querycondition_w_params More...

Typedefs
typedef struct DDS_QueryConditionImpl	DDS_QueryCondition
	<<interface>> These are specialised DDS_ReadCondition objects that allow the application to also specify a filter on the locally available data.

Functions
DDS_ReadCondition *	DDS_QueryCondition_as_readcondition (DDS_QueryCondition *query_condition)
	Access a DDS_QueryCondition's supertype instance.
const char *	DDS_QueryCondition_get_query_expression (DDS_QueryCondition *self)
	Retrieves the query expression.
DDS_ReturnCode_t	DDS_QueryCondition_get_query_parameters (DDS_QueryCondition *self, struct DDS_StringSeq *query_parameters)
	Retrieves the query parameters.
DDS_ReturnCode_t	DDS_QueryCondition_set_query_parameters (DDS_QueryCondition *self, const struct DDS_StringSeq *query_parameters)
	Sets the query parameters.

Detailed Description

DDS_QueryCondition and associated elements

Typedef Documentation

typedef struct DDS_QueryConditionImpl DDS_QueryCondition

<<interface>> These are specialised DDS_ReadCondition objects that allow the application to also specify a filter on the locally available data.

Each query condition filter is composed of a DDS_ReadCondition state filter and a content filter expressed as a query_expression and query_parameters.

The query (query_expression) is similar to an SQL WHERE clause and can be parameterised by arguments that are dynamically changeable by the set_query_parameters() operation.

Two query conditions that have the same query_expression will require unique query condition content filters if their query_paramters differ. Query conditions that differ only in their state masks will share the same query condition content filter.

Queries and Filters Syntax describes the syntax of query_expression and query_parameters.

Function Documentation

DDS_ReadCondition* DDS_QueryCondition_as_readcondition

(

DDS_QueryCondition *

query_condition

)

Access a DDS_QueryCondition's supertype instance.

Parameters

query_condition

<<in>> Cannot be NULL.

const char* DDS_QueryCondition_get_query_expression

(

DDS_QueryCondition *

self

)

Retrieves the query expression.

Parameters

self	<<in>> Cannot be NULL.

DDS_ReturnCode_t DDS_QueryCondition_get_query_parameters	(	DDS_QueryCondition *	self,
		struct DDS_StringSeq *	query_parameters
	)

Retrieves the query parameters.

Parameters

query_parameters	<<inout>> the query parameters are returned here. The memory for the strings in this sequence is managed according to the conventions described in Conventions. In particular, be careful to avoid a situation in which RTI Connext allocates a string on your behalf and you then reuse that string in such a way that RTI Connext believes it to have more memory allocated to it than it actually does.
self	<<in>> Cannot be NULL.

DDS_ReturnCode_t DDS_QueryCondition_set_query_parameters	(	DDS_QueryCondition *	self,
		const struct DDS_StringSeq *	query_parameters
	)

Sets the query parameters.

Parameters

self	<<in>> Cannot be NULL.
query_parameters	<<in>> the new query parameters