Vaadin containerFilter 选择空字段

Question

我正在使用com.vaadin.data.util.sqlcontainer.query.TableQuery 使用 MYSQL 表中的数据填充 UI 视图。

我只想显示特定字段为空的行，所以原始 SQL 是：

SELECT * FROM products WHERE monthsLeft IS null;

引用Vaadin docs，我正在使用 Vaadin SQLContainer 对象将此条件设置为 sqlContainer.addContainerFilter(new Compare.Equal("monthsLeft ", null));

但这会引发以下错误：

Sep 11, 2014 5:10:13 PM com.vaadin.server.DefaultErrorHandler doDefault SEVERE: java.lang.IllegalArgumentException: You cannot add null parameters using addParamaters(Object). Use addParameters(Object,Class) instead at com.vaadin.data.util.sqlcontainer.query.generator.StatementHelper.addParameterValue(StatementHelper.java:63) at com.vaadin.data.util.sqlcontainer.query.generator.filter.CompareTranslator.getWhereStringForFilter(CompareTranslator.java:32) at com.vaadin.data.util.sqlcontainer.query.generator.filter.QueryBuilder.getWhereStringForFilter(QueryBuilder.java:82) at com.vaadin.data.util.sqlcontainer.query.generator.filter.QueryBuilder.getJoinedFilterString(QueryBuilder.java:92) at com.vaadin.data.util.sqlcontainer.query.generator.filter.QueryBuilder.getWhereStringForFilters(QueryBuilder.java:107) at com.vaadin.data.util.sqlcontainer.query.generator.DefaultSQLGenerator.generateSelectQuery(DefaultSQLGenerator.java:107) at com.vaadin.data.util.sqlcontainer.query.TableQuery.getCount(TableQuery.java:200) at com.vaadin.data.util.sqlcontainer.SQLContainer.updateCount(SQLContainer.java:1142) at com.vaadin.data.util.sqlcontainer.SQLContainer.size(SQLContainer.java:398) at com.vaadin.ui.AbstractSelect.size(AbstractSelect.java:762) at com.vaadin.ui.Table.refreshRenderedCells(Table.java:1628) at com.vaadin.ui.Table.getVisibleCells(Table.java:3921) at com.vaadin.ui.Table.beforeClientResponse(Table.java:3155) at com.vaadin.server.communication.UidlWriter.write(UidlWriter.java:96) at com.vaadin.server.communication.UidlRequestHandler.writeUidl(UidlRequestHandler.java:149) at com.vaadin.server.communication.UidlRequestHandler.synchronizedHandleRequest(UidlRequestHandler.java:97) at com.vaadin.server.SynchronizedRequestHandler.handleRequest(SynchronizedRequestHandler.java:37) at com.vaadin.server.VaadinService.handleRequest(VaadinService.java:1329) at com.vaadin.server.VaadinServlet.service(VaadinServlet.java:236) at javax.servlet.http.HttpServlet.service(HttpServlet.java:848) at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:684) at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:503) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:137) at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:557) at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:231)

我希望有一个Compare.IsNull，但我没有看到一个

Answer 1

查看源代码，这似乎是不可能的。

这个方法没有'IS NULL'的情况：

@Override
public String getWhereStringForFilter(Filter filter, StatementHelper sh) {
    Compare compare = (Compare) filter;
    sh.addParameterValue(compare.getValue());
    String prop = QueryBuilder.quote(compare.getPropertyId());
    switch (compare.getOperation()) {
    case EQUAL:
        return prop + " = ?";
    case GREATER:
        return prop + " > ?";
    case GREATER_OR_EQUAL:
        return prop + " >= ?";
    case LESS:
        return prop + " < ?";
    case LESS_OR_EQUAL:
        return prop + " <= ?";
    default:
        return "";
    }
}

并且引用的方法 (addParameters(Object,Class)) 仅从名为 generateDeleteQuery、generateInsertQuery 和 generateUpdateQuery 的三个方法中调用。

不过提交补丁应该不会太难 ;)

Answer 2

我开始查看源代码以编写补丁，发现 com.vaadin.data.util.filter.IsNull。 解决方案是： sqlContainer.addContainerFilter(new IsNull("monthsLeft"));