JDBI SQL对象查询中的动态顺序

Question

如何在JDBI中使用SQL对象查询进行排序？

我想做类似的事情：

@SqlQuery(
    "SELECT * FROM users " +
    "WHERE something = :something " +
    "ORDER BY :orderBy :orderDir"
)
List<User> getUsers(
    @Bind("something") Integer something
  , @BindOrderBy("orderBy") String orderBy
  , @BindOrderDir("orderDir") String orderDir
);

要么

@SqlQuery(
    "SELECT * FROM users " +
    "WHERE something = :something " +
    "ORDER BY :orderBy :orderDir"
)
List<User> getUsers(
    @Bind("something") Integer something
  , @Bind("orderBy") OrderBy orderBy
  , @Bind("orderDir") OrderDir orderDir
);

Answer 1

我最近一直在探索与JDBI捆绑在一起的DropWizard，并很快遇到了同样的问题。不幸的是，JDBI的文档乏善可陈（JavaDoc和它的git存储库中的一些示例单元测试并没有单独解决），这令人失望。

这是我根据示例DAO在JDBI的Sql Object API中实现动态排序的结果：

@UseStringTemplate3StatementLocator
public interface ProductsDao {

    @RegisterMapperFactory(BeanMapperFactory.class) // will map the result of the query to a list of Product POJOs(Beans)
    @SqlQuery("select * from products order by <orderby> <order> limit :limit offset :offset")
    List<Product> getProducts(@Define("orderby") String orderBy, @Define("order") String order,
                                     @Bind("limit") int limit, @Bind("offset") int offset);

    @SqlQuery("select count(*) from products")
    int getProductsCount();

}

@ UseStringTemplate3StatementLocator-
此注释使我们可以<arg>在查询中使用语法。这些args将被我们通过@Define注释提供的任何值替换。

为了能够使用此功能，我还必须将此依赖项添加到我的pom.xml文件中：

<dependency>
  <groupId>antlr</groupId>
  <artifactId>stringtemplate</artifactId>
  <version>2.3b6</version> <!-- I am not sure if this specific version is meant to be used though -->
</dependency>

SQL注入警告 应该注意的是，Sql Injection由于将值直接插入到查询中，因此可以为我们打开大门。（:arg与@Bind使用准备好的语句并防止sql注入的查询和注释中的语法相反）。至少您应该清理将用于@Define字段的参数。（下面是DropWizard的简单示例）。

@Path("/products")
@Produces(MediaType.APPLICATION_JSON)
public class ProductsResource {
  private static ImmutableSet<String> orderByChoices = ImmutableSet.of("id", "name", "price", "manufactureDate");

  private final ProductsDao dao;

  public ProductsResource(ProductsDao dao) {
    this.dao = dao;
  }

  @GET
  // Use @InjectParam to bind many query parameters to a POJO(Bean) instead. 
  // https://jersey.java.net/apidocs/1.17/jersey/com/sun/jersey/api/core/InjectParam.html
  // i.e. public List<Product> index(@InjectParam ProductsRequest request)
  // Also use custom Java types for consuming request parameters. This allows to move such validation/sanitization logic outside the 'index' method.
  // https://jersey.java.net/documentation/1.17/jax-rs.html#d4e260 
  public List<Product> index(@DefaultValue("id")  @QueryParam("orderby") String orderBy,
                             @DefaultValue("asc") @QueryParam("order")   String order,
                             @DefaultValue("20")  @QueryParam("perpage") IntParam perpage,
                             @DefaultValue("0")   @QueryParam("page")    IntParam page)

   int limit, offset;

   order = order.toLowerCase(); 
   orderBy = orderBy.toLowerCase();

   if (!orderByChoices.contains(orderBy)) orderBy = "id"; //sanitize <orderby>
   if (order != "asc" && order != "desc") order = "asc";  //sanitize <order>

   limit = perpage.get();
   offset = page.get() < 0 ? 0 : page.get() * limit;

   return dao.getProducts(orderBy, order, limit, offset);

  }
}