按照 "getting started" diesel 教程,但使用 sqlite,原因
Following "getting started" diesel tutorial, but with sqlite, causes
我正在尝试遵循:https://diesel.rs/guides/getting-started 但我正在使用:
echo DATABASE_URL=/tmp/diesel_demo.sqlite > .env
而不是 Postgres 数据库。
我已将所有出现的 Pg
更改为 Sqlite
,并将 SERIAL
更改为 INT
,但出现以下错误:
error[E0277]: the trait bound `i32: FromSql<diesel::sql_types::Nullable<diesel::sql_types::Integer>, Sqlite>` is not satisfied
--> src/bin/show_posts.rs:14:10
|
14 | .load::<Post>(&connection)
| ^^^^ the trait `FromSql<diesel::sql_types::Nullable<diesel::sql_types::Integer>, Sqlite>` is not implemented for `i32`
How to get a result set where field value == row number?
show_posts.rs:
extern crate diesel_demo;
extern crate diesel;
use self::diesel_demo::*;
use self::models::*;
use self::diesel::prelude::*;
fn main() {
use diesel_demo::schema::posts::dsl::*;
let connection = establish_connection();
let results = posts.filter(published.eq(true))
.limit(5)
.load::<Post>(&connection)
.expect("Error loading posts");
println!("Displaying {} posts", results.len());
for post in results {
println!("{}", post.title);
println!("----------\n");
println!("{}", post.body);
}
}
up.sql:
CREATE TABLE posts (
id INTEGER PRIMARY KEY,
title VARCHAR NOT NULL,
body TEXT NOT NULL,
published BOOLEAN NOT NULL DEFAULT 'f'
)
models.rs(自动生成):
#[derive(Queryable)]
pub struct Post {
pub id: i32,
pub title: String,
pub body: String,
pub published: bool,
}
我不明白为什么 Diesel 期望 id
成为 Nullable
。
将 NOT NULL
添加到 up.sql
中的 id
字段修复了它。
我正在尝试遵循:https://diesel.rs/guides/getting-started 但我正在使用:
echo DATABASE_URL=/tmp/diesel_demo.sqlite > .env
而不是 Postgres 数据库。
我已将所有出现的 Pg
更改为 Sqlite
,并将 SERIAL
更改为 INT
,但出现以下错误:
error[E0277]: the trait bound `i32: FromSql<diesel::sql_types::Nullable<diesel::sql_types::Integer>, Sqlite>` is not satisfied
--> src/bin/show_posts.rs:14:10
|
14 | .load::<Post>(&connection)
| ^^^^ the trait `FromSql<diesel::sql_types::Nullable<diesel::sql_types::Integer>, Sqlite>` is not implemented for `i32`
How to get a result set where field value == row number?
show_posts.rs:
extern crate diesel_demo;
extern crate diesel;
use self::diesel_demo::*;
use self::models::*;
use self::diesel::prelude::*;
fn main() {
use diesel_demo::schema::posts::dsl::*;
let connection = establish_connection();
let results = posts.filter(published.eq(true))
.limit(5)
.load::<Post>(&connection)
.expect("Error loading posts");
println!("Displaying {} posts", results.len());
for post in results {
println!("{}", post.title);
println!("----------\n");
println!("{}", post.body);
}
}
up.sql:
CREATE TABLE posts (
id INTEGER PRIMARY KEY,
title VARCHAR NOT NULL,
body TEXT NOT NULL,
published BOOLEAN NOT NULL DEFAULT 'f'
)
models.rs(自动生成):
#[derive(Queryable)]
pub struct Post {
pub id: i32,
pub title: String,
pub body: String,
pub published: bool,
}
我不明白为什么 Diesel 期望 id
成为 Nullable
。
将 NOT NULL
添加到 up.sql
中的 id
字段修复了它。