如何使用Ebean查询原始SQL时映射结果 [英] How to map Results when Querying raw SQL using Ebean
问题描述
使用由Ebean创建的Postgres表,我想用手写的语句查询这些表:
Using Postgres Tables created by Ebean, I would like to query these tables with a hand-written statement:
SELECT r.name,
r.value,
p.name as param1,
a.name as att1,
p2.name as param2,
a2.name as att2
FROM compatibility c
JOIN attribute a ON c.att1_id = a.id
JOIN attribute a2 ON c.att2_id = a2.id
JOIN PARAMETER p ON a.parameter_id = p.id
JOIN PARAMETER p2 ON a2.parameter_id = p2.id
JOIN rating r ON c.rating_id = r.id
WHERE p.problem_id = %d
OR p2.problem_id = %d
每个连接的表代表我的一个模型类。
查询执行正常,但我不知道如何继续:
Each of the joined tables represent one of my model classes. The query executes fine, but I don't know how I would proceed:
如何使用Play 2.2执行查询。和Ebean?
如何将此查询映射到可迭代对象?我是否需要创建一个包含查询中所有字段的Model类,还是可以使用某种HashMap?
如何以安全的方式参数化查询?
How do I even execute the query using Play 2.2. and Ebean? How can I map this query to an iterable object? Do I need to create a Model class which contains all the fields from the query, or can I use some sort of HashMap? How can I parameterize the query in a safe way?
推荐答案
要执行此查询,您需要使用RawSql类。您还必须创建要将结果投射到的类。
To execute this query you need to use RawSql class. You will also have to create class to which results will be casted.
以下是示例结果类的代码:
Here is a code of exemplary result class:
import javax.persistence.Entity;
import com.avaje.ebean.annotation.Sql;
@Entity
@Sql
public class Result {
String name;
Integer value;
String param1;
String param2;
String att1;
String att2;
}
执行此查询的示例:
String sql
= " SELECT r.name,"
+ " r.value,"
+ " p.name as param1,"
+ " a.name as att1,"
+ " p2.name as param2,"
+ " a2.name as att2"
+ " FROM compatibility c"
+ " JOIN attribute a ON c.att1_id = a.id"
+ " JOIN attribute a2 ON c.att2_id = a2.id"
+ " JOIN PARAMETER p ON a.parameter_id = p.id"
+ " JOIN PARAMETER p2 ON a2.parameter_id = p2.id"
+ " JOIN rating r ON c.rating_id = r.id"
+ " WHERE p.problem_id = %d"
+ " OR p2.problem_id = %d"
RawSql rawSql =
RawSqlBuilder
.parse(sql)
.columnMapping("r.name", "name")
.columnMapping("r.value", "value")
.create();
Query<Result> query = Ebean.find(Result.class);
query.setRawSql(rawSql)
.where().gt("amount", 10);
List<Result> list = query.findList();
这篇关于如何使用Ebean查询原始SQL时映射结果的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!