使用 JDOQL 获取“包含”结果时出现问题要求

发布于 2024-09-24 21:30:48 字数 405 浏览 2 评论 0原文

我正在使用 Google App Engine 进行项目，并且需要对数据库进行一些查询。我使用JDOQL来询问数据库。就我而言，我想获取包含子字符串“array”的大学。我认为我的查询有错误，因为它按字母顺序返回大学名称，而不是包含子字符串的大学名称。

Query query = pm.newQuery("SELECT FROM " + University.class.getName() + " WHERE name.contains("+array+") ORDER BY name RANGE 0, 5");

有人可以告诉我我的查询有什么问题吗？

感谢您的帮助！

编辑

我有一个大学商店列表，我有一个建议框，我们可以在其中按他的名字请求一所大学。我想自动完成请求的名称。

原文

I am using Google App Engine for a project and I need to do some queries on the database. I use the JDOQL to ask the database. In my case I want to obtain the university that contains the substring "array". I think my query has a mistake because it returns the name of universities in the alphabetical order and not the ones containing the substring.

Query query = pm.newQuery("SELECT FROM " + University.class.getName() + " WHERE name.contains("+array+") ORDER BY name RANGE 0, 5");

Could someone tell me what's wrong in my query?

Thank you for your help!

EDIT

I have a list of universities store and I have a suggestbox where we can request a university by his name. And I want to autocomplete the requested name.

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ま柒月 2024-10-01 21:30:48

App Engine 不支持全文搜索，您应该为问题 217。然而，部分解决方法是可能的。对于你的情况，我认为这是一个很好的选择。

首先，调整你的模型，使名称也有一个小写（或大写）版本——我假设它被称为 lname。除非您希望查询区分大小写。

然后你这样查询：

Query query = pm.newQuery(University.class);
query.setFilter("lname >= startNameParam");
query.setFilter("lname < stopNameParam");
query.setOrdering("lname asc");
query.declareParameters("String startNameParam");
query.declareParameters("String stopNameParam");
query.setRange(0, 5);
List<University> results = (List<University>) query.execute(search_value, search_value + "z");

App engine does not support full-text searches, you should star issue 217. However, A partial workaround is possible. And in your case I think it is a good fit.

First thing, adjust your model such that there is a lower (or upper case) version of the name as well -- I will assume it is called lname. Unless you want your queries to be case-sensitive.

Then you query like this:

Query query = pm.newQuery(University.class);
query.setFilter("lname >= startNameParam");
query.setFilter("lname < stopNameParam");
query.setOrdering("lname asc");
query.declareParameters("String startNameParam");
query.declareParameters("String stopNameParam");
query.setRange(0, 5);
List<University> results = (List<University>) query.execute(search_value, search_value + "z");

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如痴如狂 2024-10-01 21:30:48

正确的方法是这样的 -

Query query = pm.newQuery(University.class,":p.contains(name)");
query.setOrdering("name asc");
query.setRange(0, 5);
List univs = q.execute(Arrays.asList(array));

（注意 - 在这种情况下 :p 是一个隐式参数名称，您可以替换为任何名称）

The correct way to do this is like this -

Query query = pm.newQuery(University.class,":p.contains(name)");
query.setOrdering("name asc");
query.setRange(0, 5);
List univs = q.execute(Arrays.asList(array));

(note- In this case the :p is an implicit param name you can replace with any name)

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