Examples with Query com.google.appengine.api.datastore.Query used on opensource projects

Example 26 with Query

use of com.google.appengine.api.datastore.Query in project java-docs-samples by GoogleCloudPlatform.

the class MetadataNamespacesTest method getNamespaces.

// [START namespace_query_example]
List<String> getNamespaces(DatastoreService ds, String start, String end) {
    // Start with unrestricted namespace query
    Query q = new Query(Entities.NAMESPACE_METADATA_KIND);
    List<Filter> subFilters = new ArrayList();
    // Limit to specified range, if any
    if (start != null) {
        subFilters.add(new FilterPredicate(Entity.KEY_RESERVED_PROPERTY, FilterOperator.GREATER_THAN_OR_EQUAL, Entities.createNamespaceKey(start)));
    }
    if (end != null) {
        subFilters.add(new FilterPredicate(Entity.KEY_RESERVED_PROPERTY, FilterOperator.LESS_THAN_OR_EQUAL, Entities.createNamespaceKey(end)));
    }
    q.setFilter(CompositeFilterOperator.and(subFilters));
    // Initialize result list
    List<String> results = new ArrayList<String>();
    // Build list of query results
    for (Entity e : ds.prepare(q).asIterable()) {
        results.add(Entities.getNamespaceFromNamespaceKey(e.getKey()));
    }
    // Return result list
    return results;
}

Example 27 with Query

use of com.google.appengine.api.datastore.Query in project java-docs-samples by GoogleCloudPlatform.

the class MetadataKindsTest method printLowercaseKinds.

// [START kind_query_example]
void printLowercaseKinds(DatastoreService ds, PrintWriter writer) {
    // Start with unrestricted kind query
    Query q = new Query(Entities.KIND_METADATA_KIND);
    List<Filter> subFils = new ArrayList();
    // Limit to lowercase initial letters
    subFils.add(new FilterPredicate(Entity.KEY_RESERVED_PROPERTY, FilterOperator.GREATER_THAN_OR_EQUAL, Entities.createKindKey("a")));
    // Character after 'z'
    String endChar = Character.toString((char) ('z' + 1));
    subFils.add(new FilterPredicate(Entity.KEY_RESERVED_PROPERTY, FilterOperator.LESS_THAN, Entities.createKindKey(endChar)));
    q.setFilter(CompositeFilterOperator.and(subFils));
    // Print heading
    writer.println("Lowercase kinds:");
    // Print query results
    for (Entity e : ds.prepare(q).asIterable()) {
        writer.println("  " + e.getKey().getName());
    }
}

Example 28 with Query

use of com.google.appengine.api.datastore.Query in project java-docs-samples by GoogleCloudPlatform.

the class IndexesServlet method doGet.

@Override
public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException {
    // [START exploding_index_example_1]
    Query q = new Query("Widget").setFilter(CompositeFilterOperator.and(new FilterPredicate("x", FilterOperator.EQUAL, 1), new FilterPredicate("y", FilterOperator.EQUAL, 2))).addSort("date", Query.SortDirection.ASCENDING);
    // [END exploding_index_example_1]
    List<Entity> results = datastore.prepare(q).asList(FetchOptions.Builder.withDefaults());
    PrintWriter out = resp.getWriter();
    out.printf("Got %d widgets.\n", results.size());
}

Example 29 with Query

use of com.google.appengine.api.datastore.Query in project java-docs-samples by GoogleCloudPlatform.

the class ProjectionServlet method doGet.

@Override
public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
    resp.setContentType("text/plain");
    resp.setCharacterEncoding("UTF-8");
    PrintWriter out = resp.getWriter();
    out.printf("Latest entries from guestbook: \n");
    Key guestbookKey = KeyFactory.createKey("Guestbook", GUESTBOOK_ID);
    Query query = new Query("Greeting", guestbookKey);
    addGuestbookProjections(query);
    printGuestbookEntries(datastore, query, out);
}

Example 30 with Query

use of com.google.appengine.api.datastore.Query in project java-docs-samples by GoogleCloudPlatform.

the class ListPeopleServlet method doGet.

@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    FetchOptions fetchOptions = FetchOptions.Builder.withLimit(PAGE_SIZE);
    // If this servlet is passed a cursor parameter, let's use it.
    String startCursor = req.getParameter("cursor");
    if (startCursor != null) {
        fetchOptions.startCursor(Cursor.fromWebSafeString(startCursor));
    }
    Query q = new Query("Person").addSort("name", SortDirection.ASCENDING);
    PreparedQuery pq = datastore.prepare(q);
    QueryResultList<Entity> results;
    try {
        results = pq.asQueryResultList(fetchOptions);
    } catch (IllegalArgumentException e) {
        // IllegalArgumentException happens when an invalid cursor is used.
        // A user could have manually entered a bad cursor in the URL or there
        // may have been an internal implementation detail change in App Engine.
        // Redirect to the page without the cursor parameter to show something
        // rather than an error.
        resp.sendRedirect("/people");
        return;
    }
    resp.setContentType("text/html");
    resp.setCharacterEncoding("UTF-8");
    PrintWriter w = resp.getWriter();
    w.println("<!DOCTYPE html>");
    w.println("<meta charset=\"utf-8\">");
    w.println("<title>Cloud Datastore Cursor Sample</title>");
    w.println("<ul>");
    for (Entity entity : results) {
        w.println("<li>" + entity.getProperty("name") + "</li>");
    }
    w.println("</ul>");
    String cursorString = results.getCursor().toWebSafeString();
    // This servlet lives at '/people'.
    w.println("<a href='/people?cursor=" + cursorString + "'>Next page</a>");
}