CODEWITHSUNDEEP
rustrust-sqlx
Alexander Staroselsky
Alexander Staroselsky

Reputation: 38777

How to use custom type for sqlx::query_as result? Getting "trait bound FromRow is not satisfied" error

Trying to get past an error in Rust and sqlx (0.7x) using query_as and fetch_all functions and a defined struct. Goal is to query from sqlite and deserialize to a vec of struct.

use serde::{Deserialize, Serialize};
use sqlx::sqlite::SqlitePoolOptions;

#[derive(Serialize, Deserialize)]
struct Todo {
    id: String,
    completed: bool,
}

#[tokio::main]
async fn main() {
    // set up connection pool
    let pool = SqlitePoolOptions::new()
        // .max_connections(5)
        // .acquire_timeout(Duration::from_secs(3))
        .connect("sqlite:mydatabase.db")
        .await
        .expect("can't connect to database");

    let todos: Vec<Todo> = sqlx::query_as::<_, Todo>("SELECT * FROM todos")
        .fetch_all(&pool)
        .await
        .unwrap();
}

Error is as follows:

the trait bound `for<'r> Todo: FromRow<'r, _>` is not satisfied
the following other types implement trait `FromRow<'r, R>`:
  ()
  (T1,)
  (T1, T2)
  (T1, T2, T3)
  (T1, T2, T3, T4)
  (T1, T2, T3, T4, T5)
  (T1, T2, T3, T4, T5, T6)
  (T1, T2, T3, T4, T5, T6, T7)
and 9 others

the method `fetch_all` exists for struct `QueryAs<'_, _, Todo, _>`, but its trait bounds were not satisfied
the following trait bounds were not satisfied:
    `Todo: FromRow<'r, _>`

Upvotes: 1

Views: 694

Answers (1)

Alexander Staroselsky
Alexander Staroselsky

Reputation: 38777

Adding FromRow resolved this issue:

use sqlx::{FromRow};

#[derive(Serialize, Deserialize, FromRow)]
struct Todo {
    id: String,
    completed: bool,
}

Upvotes: 1

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