␡
- Permission and Application Space
- Benefits of Content Providers
- And the Drawbacks
- So What to Choose?
- Applied Example: MyWalks
- Adding Location Points
- Narrowing the Data Returned by a Query
- Conclusion
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Narrowing the Data Returned by a Query
Following the RFC standard, we can use specific URIs to narrow down the data we are querying for. In our application, we might want to select a walk depending on its creation date. A URI of the following form, would be used (the from and to fields are in "zero epoch" value):
content://com.informit.mywalks.Walks/walks?from=1174497980534&to=1174497980536
To enable such a query, we will set the where clause in the query method of the instantiated content provider, as follows:
String from = uri.getQueryParameter("from");
tring to = uri.getQueryParameter("to");
if (from != null) {
qb.appendWhere("created>" + from);
}
if (to != null) {
// There seems to be a bug here. We need to manually ensure the AND
// is part of the where clause
qb.appendWhere(" AND created<" + to);
}
The code is straightforward, and you can extend it to any key/value pair. You can build up more complicated URIs in order to access the data in different ways.