如何为JSON解析指定数据类型？-Java 学习之路

我有一个JSON响应，它是一个哈希数组：

[{"project" => {"id" => 1, "name" => "Internal"},
 {"project" => {"id" => 2, "name" => "External"}}]

我的代码如下所示：

client = HTTP::Client.new(url, ssl: true)
response = client.get("/projects", ssl: true)
projects = JSON.parse(response.body) as Array

我试过 as Array(Hash) ，但这给了我 can't use Hash(K, V) as generic type argument yet, use a more specific type .

如何指定类型？

2 回答

您必须在访问元素时强制转换这些元素：

projects = JSON.parse(json).as(Array)
project = projects.first.as(Hash)["project"].as(Hash)
id = project["id"].as(Int64)

http://carc.in/#/r/f3f

但对于像这样的结构良好的数据，你最好使用 JSON.mapping ：

class ProjectContainer
  JSON.mapping({
    project: Project
  })
end

class Project
  JSON.mapping({
    id: Int64,
    name: String
  })
end

projects = Array(ProjectContainer).from_json(json)
project = projects.first.project
pp id = project.id

http://carc.in/#/r/f3g

您可以在https://github.com/manastech/crystal/issues/982#issuecomment-121156428查看有关此问题的更详细说明

回复于 2024-04-24T21:02:16+08:00

3
你继续在每一步中施展：
```
projects = JSON.parse(response.body) as Array
projects.each do |project|
  project = project as Hash
  project = project["project"] as Hash
  id = project["id"] as Int
  name = project["name"] as String
end
```
但是，如果您的API响应具有众所周知的结构，我强烈建议您使用JSON.mapping：https://crystal-lang.org/api/0.22.0/JSON.html#mapping-macro
回复于 2024-04-24T21:02:16+08:00

如何为JSON解析指定数据类型？

2 回答

相关问题