IEventControl::SetDefaultQuery method (eventsys.h)

Sets the default query to determine subscribers.

Syntax

HRESULT SetDefaultQuery(
  [in]          BSTR methodName,
  [in]          BSTR criteria,
  [out, retval] int  *errorIndex
);

Parameters

[in] methodName

The name of the method to which the default query is assigned.

[in] criteria

The query criteria. This parameter cannot be NULL. For details on forming a valid expression for this parameter, see the Remarks section below.

[out, retval] errorIndex

The location, expressed as an offset, of an error in the criteria parameter.

Return value

If this method succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code.

Remarks

The query criteria specified by the criteria parameter can be "ALL", to specify a request for all subscription objects, or a Boolean expression denoting one or more conditions a subscription object must meet to be included in the query result. Valid expressions are of the following form:

[NOT] propertynamerelationalOperatorvalue. Valid relational operators are as follows:

==, =, !=, <>, ~=. Valid values are "string", 'string', {GUID}, TRUE, FALSE, NULL.

Individual Boolean expressions can be joined with AND or OR. Expressions can be nested in parentheses to enforce a specific order of evaluation.

Following are some examples of valid query criteria:

"EventClassID == {F89859D1-6565-11D1-88C8-0080C7D771BF}"

"EventClassID == {F89859D1-6565-11D1-88C8-0080C7D771BF} AND MethodName = 'StockPriceChange'"

Requirements

See also

IEventControl