如何在 Rust 中过滤多维数组？

Question

我有下面的 JSON 数据，我需要使用 Rust 解析它。使用 serde，我可以访问一些 JSON：

let v: serde_json::Value = serde_json::from_str(&data).expect("Unable to parse");
let sessions = v["data"]["sessions"].as_array().unwrap();
let programs = v["data"]["programs"].as_array().unwrap();

但是如何使用

programData

值过滤单个

programs.id

数组项？我正在尝试这样的事情，但我做不到：

    for x in programs {
            let programId = &x["id"];

            // not working - produces 'no implementation' error while building
            let programSessions = sessions.iter().filter(|&f| f["programData"].as_array().unwrap()["programRefId"] == programId).collect();
        }

{
  "data": {
    "name": "my name",
    "sessions": [
      {
        "id": 1,
        "programData": [
          {
            "dataPhase": 1,
            "programRefId": 2,
            "programSpecificData": {
              "completed": false
            }
          },
          {
            "dataPhase": 2,
            "programRefId": 3,
            "programSpecificData": {
              "completed": true
            }
          }
        ]
      }
    ],
    "programs": [
      {
        "id": 3
      }
    ]
  }
}

Answer 1

如果您想使用

programData

过滤单个

program.id

数组项，您需要更改一些内容。看起来您正在直接将嵌套结构中的

serde_json::Value

与另一个

serde_json::Value

进行比较，这可能会导致问题。您还尝试对

programData

进行过滤，就好像它是单个对象，而实际上它是一个数组。

您应该循环遍历每个程序，然后对于每个程序循环遍历每个会话，然后在每个会话过滤器中基于

programData

的项目。programRefId

Rust Playground 链接

use serde_json::Value;

fn main() {
    let data = r#"
    {
        "data": {
            "name": "my name",
            "sessions": [
                {
                    "id": 1,
                    "programData": [
                        {
                            "dataPhase": 1,
                            "programRefId": 2,
                            "programSpecificData": {
                                "completed": false
                            }
                        },
                        {
                            "dataPhase": 2,
                            "programRefId": 3,
                            "programSpecificData": {
                                "completed": true
                            }
                        }
                    ]
                }
            ],
            "programs": [
                {
                    "id": 3
                }
            ]
        }
    }
    "#;

    let v: Value = serde_json::from_str(data).expect("Unable to parse");
    let sessions = v["data"]["sessions"].as_array().unwrap();
    let programs = v["data"]["programs"].as_array().unwrap();

    for program in programs {
        let program_id = program["id"].as_i64().unwrap(); // Assuming id is always an integer.

        for session in sessions {
            let program_data = session["programData"].as_array().unwrap();

            let program_sessions: Vec<&Value> = program_data.iter().filter(|&f| {
                // Assuming programRefId is always present and an integer.
                f["programRefId"].as_i64() == Some(program_id)
            }).collect();

            // Now you have the filtered programSessions for the current program_id
            // Do something with program_sessions...
            println!("Filtered program sessions for program id {}: {:?}", program_id, program_sessions);
        }
    }
}