如何在 sqlalchemy 查询中选择文字值? [英] How do I select literal values in an sqlalchemy query?

问题描述

我有一个看起来像这样的查询:

I have a query which looks like this:

query = session.query(Item) \
    .filter(Item.company_id == company_id) \
    .order_by(Item.id)

这是一个非常基本的查询.除了提取 Item 的值之外，我还想在组合中附加一个附加值，并将其返回给我.在原始 SQL 中，我会这样做:

It's a pretty basic query. In addition to pulling out the values for the Item, I want to append an additional value into the mix, and have it returned to me. In raw SQL, I would do this:

SELECT *, 0 as subscribed
FROM items
WHERE company_id = 34
ORDER BY id

如何通过 sqlalchemy 手动添加该值?

How can I manually add that value via sqlalchemy?

推荐答案

您需要使用 literal_column，看起来有点像这样:

You'll need to use a literal_column, which looks a bit like this:

sqlalchemy.orm.Query(Item, sqlalchemy.sql.expression.literal_column("0"))

请注意 text 参数是在没有任何转换的情况下插入到查询中的；如果您从应用程序外部接受文本参数的值，这可能会使您面临 SQL 注入漏洞.如果这是你需要的东西，你会想要使用 bindparam，使用起来也差不多；但你必须创造一个名字:

Beware that the text argument is inserted into the query without any transformation; this may expose you to a SQL Injection vulnerability if you accept values for the text parameter from outside your application. If that's something you need, you'll want to use bindparam, which is about as easy to use; but you will have to invent a name:

sqlalchemy.orm.Query(Item, sqlalchemy.sql.expression.bindparam("zero", 0))

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