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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_ReadConditionDDS_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

RTI Connext C API Version 6.0.0 Copyright © Sun Mar 3 2019 Real-Time Innovations, Inc