如何将HashMap作为JSON类型插入PostgreSQL？

contacts有一个HashMap的数据结构，我使用PostgreSQL客户机-将contacts的键和值插入表中，然后我想从表中进行选择。下面是我到目前为止所做的尝试。我需要帮助写正确的语法

use postgres::{Client, NoTls};
use std::collections::HashMap;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut client = Client::connect("host=127.0.0.1 user=postgres", NoTls)?;

    client.simple_query("
        DROP TABLE 
        IF EXISTS following_relation;
        ")?;

    client.simple_query("
        CREATE TABLE following_relation (
            id               SERIAL NOT NULL PRIMARY KEY,
            relation         JSON NOT NULL
        )
    ")?;

    let mut contacts = HashMap::new();
    let mut v: Vec<String> = Vec::new();

    v = vec!["jump".to_owned(), "jog".to_string()];
    contacts.insert("Ashley", v.clone());

    for (name, hobby) in contacts.iter() {
        // 1. How to write sql statement with parameters?
        client.execute(
        "INSERT INTO following_relation(relation) 
         VALUE ('{"name" : $1, "hobby" : $2}')", 
        &[&name, &hobby],
    )?;  
    }

    for row in client.query("SELECT id, relation FROM following_relation", &[])? {
        // 2. How to read from parse the result?
        let id: i32 = row.get(0);
        let relation = row.get(1);
        //println!("found person: {} {} {:?}", id, relation["name"], relation["hobby"]); 
    }
    Ok(())
}

更新后，我尝试使用更简短的代码示例

use postgres::{Client, NoTls};
use postgres::types::Json;
use serde::{Deserialize, Serialize};

#[derive(Debug, Serialize, Deserialize)]
struct relations {
    name : String,
    hobby: Vec<String>
}
pub struct Json<T>(pub T);

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut client = Client::connect("host=127.0.0.1 user=postgres", NoTls)?;

    client.simple_query("
        DROP TABLE 
        IF EXISTS following_relation;

        ")?;

    client.simple_query("
        CREATE TABLE following_relation (
            id      SERIAL PRIMARY KEY,
            relation    JSON NOT NULL
        )
    ")?;

    let rel = relations {
        name: "czfzdxx".to_string(),
        hobby: vec![
            "basketball".to_string(),
            "jogging".to_string()
        ],
    };

    client.execute(
        r#"INSERT INTO following_relation(relation)
             VALUE ($1)"#,
        &[&Json(&rel)]
    )?;

    Ok(())
}

你想要生锈：

contacts.iter中的姓名、爱好{ client.execute 插入以下关系 值“{name:$1，hobby:$2}”， &[&name，&following]， ?; } 在起始r和结束之间，字符串文字可以有除自身以外的任何字符，而无需转义。如果您也需要它自己，则以多个s开始原始字符串文本，以匹配的s结束。

这里是main.rs：

---

以下是使用的相关文档：和。搜索serde_json、ToSql和FromSql traits是为这种第三方类型实现的。

我无法让它工作，这是我得到的结果，因此您可以从中提取cargo.toml@pbn我将立即查看。您是否可以添加用于解析client.querySELECT Relationship from_Relationship，&[]令人惊讶的是，它不是直截了当的。我发现可以尝试使用serde_json:：Value代替postgres中的json。我只是编辑了代码。看看它是否适合你。复制粘贴所有内容，因为我也更改了类型名称以删除警告。@complexildphenomenon抱歉地说，我将在晚上查看它，我只是忘了。

use postgres::{Client, NoTls};
use postgres::types::Json;
use serde::{Deserialize, Serialize};

#[derive(Debug, Serialize, Deserialize)]
struct relations {
    name : String,
    hobby: Vec<String>
}
pub struct Json<T>(pub T);

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut client = Client::connect("host=127.0.0.1 user=postgres", NoTls)?;

    client.simple_query("
        DROP TABLE 
        IF EXISTS following_relation;

        ")?;

    client.simple_query("
        CREATE TABLE following_relation (
            id      SERIAL PRIMARY KEY,
            relation    JSON NOT NULL
        )
    ")?;

    let rel = relations {
        name: "czfzdxx".to_string(),
        hobby: vec![
            "basketball".to_string(),
            "jogging".to_string()
        ],
    };

    client.execute(
        r#"INSERT INTO following_relation(relation)
             VALUE ($1)"#,
        &[&Json(&rel)]
    )?;

    Ok(())
}

error[E0432]: unresolved import `postgres::types::Json`

use postgres::{Client, NoTls};
use serde::{Deserialize, Serialize};
use postgres_types::Json;
use postgres_types::{FromSql};


#[derive(Debug, Deserialize, Serialize, FromSql)]
struct Relation {
    name : String,
    hobby: Vec<String>
}

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut client = Client::connect("host=127.0.0.1 user=postgres", NoTls)?;

    client.simple_query("
        DROP TABLE 
        IF EXISTS following_relation;

        ")?;

    client.simple_query("
        CREATE TABLE following_relation (
            id      SERIAL PRIMARY KEY,
            relation    JSON NOT NULL
        )
    ")?;

    let rel = Relation {
        name: "czfzdxx".to_string(),
        hobby: vec![
            "basketball".to_string(),
            "jogging".to_string()
        ],
    };

    client.execute(
        "INSERT INTO following_relation (relation) VALUES ($1)",
        &[&Json::<Relation>(rel)]
    )?;

    for row in &client.query("SELECT relation FROM following_relation", &[]).unwrap() {
        let rel: Json<Relation> = row.get(0);
        println!("{:?}", rel);
    }

    Ok(())
}

[package]
name = "testapp"
version = "0.1.0"
edition = "2018"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
postgres = {version = "0.17.0"}
tokio-postgres = "0.5.1"
serde = {version = "1.0.104", features = ["derive"]}
postgres-types = {version = "0.1.0", features = ["derive", "with-serde_json-1"]}
serde_json = "1.0.45"