异常动态过滤器 [英] anorm dynamic filters

问题描述

我正在研究一些 anorm 文档(来自 play 框架)，并不清楚它是否支持常见的查询用例:动态过滤器，即用户在 10 个字段的搜索表单上填写 2 或 3 个搜索条件.

I'm studying a little the anorm documentation (from play framework) and is not clear if it supports a common query use case: dynamic filters, that is the user fills in 2 or 3 search criteria on a 10 fields search form.

在这种情况下，如何在没有经典字符串操作的情况下动态构造查询?

In this case how can I dynamically construct the query without the classic string manipulation?

推荐答案

是的，我认为 Robin Green 引用的问题包含了答案.只需使用占位符(例如 {criterion1})用所有可能的条件定义您的查询，并在查询上调用 on() 方法，传递实际的 Seq<接受的答案中描述的 Option 参数的/code>.

Yes, I think the question referenced by Robin Green contains the answer. Just define your query with all the possible criteria using placeholders (e.g. {criterion1}) and call the on() method on the query, passing the actual Seq of Option parameters as described in the accepted answer.

来自 Anorm 文档的修改示例，假设您有两个条件，但只希望您的查询过滤国家代码而不是首都:

Modified example from the Anorm doc, assuming you have two criteria but only want your query to filter on the country code and not on the capital:

SQL(
"""
select * from Country c 
join CountryLanguage l on l.CountryCode = c.Code 
where ({countryCode} is null or c.code = {countryCode})
  and ({capital} is null or c.capital = {capital});
"""
).on("countryCode" -> Some("FRA"), "capital" -> None)

这应该可以解决问题.

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