如何转换PSQL :: json @> :: json转换为jpa/jpql-predicate [英] How to convert PSQLs ::json @> ::json to a jpa/jpql-predicate

问题描述

说我有一个看起来像这样的数据库表:

Say i have a db-table looking like this:

CREATE TABLE myTable(
   id BIGINT, 
   date TIMESTAMP, 
   user_ids JSONB 
);

user_ids是JSONB-ARRAY

让此表的记录如下所示:

Let a record of this table look like this:

{
     "id":13,
     "date":"2019-01-25 11:03:57",
     "user_ids":[25, 661, 88]
};

我需要查询user_ids包含25的所有记录.在SQL中，我可以使用以下选择语句来实现它:

I need to query all records where user_ids contain 25. In SQL i can achieve it with the following select-statement:

SELECT * FROM myTable where user_ids::jsonb @> '[25]'::jsonb;

现在，我需要编写一个JPA-Predicate，将"user_ids::jsonb @> '[25]'::jsonb"呈现为休眠的可解析/可执行标准，然后在session.createQuery()语句中使用该标准. 简单来说，我需要知道如何将PSQL片段(user_ids::jsonb @> '[25]'::jsonb)编写为HQL表达式.

Now i need to write a JPA-Predicate that renders "user_ids::jsonb @> '[25]'::jsonb" to a hibernate parseable/executable Criteria, which i then intent to use in a session.createQuery() statement. In simpler terms i need to know how i can write that PSQL-snippet (user_ids::jsonb @> '[25]'::jsonb) as a HQL-expression.

推荐答案

幸运的是，PostgreSQL中的每个比较运算符都只是函数的别名，您可以在psql控制台中键入\doS+并找到别名.运算符(尽管在此搜索中某些运算符被认为是通配符，所以它们给出的结果超出预期).

Fortunately, every comparison operator in PostgreSQL is merely an alias to a function, and you can find the alias through the psql console by typing \doS+ and the operator (although some operators are considered wildcards in this search, so they give more results than desired).

这是结果:

postgres=# \doS+ @>
                                          List of operators
   Schema   | Name | Left arg type | Right arg type | Result type |      Function       | Description 
------------+------+---------------+----------------+-------------+---------------------+-------------
 pg_catalog | @>   | aclitem[]     | aclitem        | boolean     | aclcontains         | contains
 pg_catalog | @>   | anyarray      | anyarray       | boolean     | arraycontains       | contains
 pg_catalog | @>   | anyrange      | anyelement     | boolean     | range_contains_elem | contains
 pg_catalog | @>   | anyrange      | anyrange       | boolean     | range_contains      | contains
 pg_catalog | @>   | box           | box            | boolean     | box_contain         | contains
 pg_catalog | @>   | box           | point          | boolean     | box_contain_pt      | contains
 pg_catalog | @>   | circle        | circle         | boolean     | circle_contain      | contains
 pg_catalog | @>   | circle        | point          | boolean     | circle_contain_pt   | contains
 pg_catalog | @>   | jsonb         | jsonb          | boolean     | jsonb_contains      | contains
 pg_catalog | @>   | path          | point          | boolean     | path_contain_pt     | contains
 pg_catalog | @>   | polygon       | point          | boolean     | poly_contain_pt     | contains
 pg_catalog | @>   | polygon       | polygon        | boolean     | poly_contain        | contains
 pg_catalog | @>   | tsquery       | tsquery        | boolean     | tsq_mcontains       | contains
(13 rows)

您想要的是两侧的jsonb参数，我们看到的函数称为jsonb_contains.因此，与jsonbcolumn @> jsonbvalue等效的是jsonb_contains(jsonbcolumn, jsonbvalue).现在，除非在使用Hibernate的情况下通过自定义方言注册它，否则就不能在JPQL或CriteriaBuilder中使用该函数.如果您使用的是EclipseLink，我不知道那里的情况.

What you want is jsonb arguments on both sides, and we see the function that has that is called jsonb_contains. So the equivalent to jsonbcolumn @> jsonbvalue is jsonb_contains(jsonbcolumn, jsonbvalue). Now you can't use the function in either JPQL or CriteriaBuilder, unless you register it through a custom Dialect if you're using Hibernate. If you're using EclipseLink, I don't know the situation there.

从这里开始，您的选择是使用本机查询，或通过扩展现有的本地查询来添加自己的Hibernate方言.

From here on, your options are to use native queries, or add your own Hibernate Dialect by extending an existing one.

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