如何使用柴油的過濾方法

Question

我有一個小小的actix web 項目。 有一個這樣的模型：

#[derive(Serialize, Deserialize, Insertable, Identifiable, Queryable, PartialEq, Debug)]
#[table_name = "confirmations"]
pub struct Confirmation {
    pub id: Uuid,
    pub email: String,
    pub expires_at: chrono::NaiveDateTime
}

然后我有一個函數，我只想從數據庫中獲取項目。 我嘗試這樣做：

pub fn get_confirmation_item(
    id: &Uuid,
    email: &str,
    pool: &web::Data<PgDBPool>
) -> Result<Confirmation, AppError> {
    let connection = pool.get().unwrap();
    let result = confirmations
        .filter(id.eq(id))
        .filter(email.eq(email))
        .select(id)
        .first(&connection);
    Ok(result)
}

最后我得到了這個錯誤：

 error[E0277]: the trait bound `bool: diesel::Expression` is not satisfied --> src/apps/users/utils.rs:45:17 | 45 | .filter(id.eq(id)) | ^^^^^^^^^ the trait `diesel::Expression` is not implemented for `bool` | = note: required because of the requirements on the impl of `diesel::query_dsl::filter_dsl::FilterDsl<bool>` for

diesel::query_builder::SelectStatement<schema::confirmations::table>

 error[E0277]: the trait bound `bool: diesel::expression::NonAggregate` is not satisfied --> src/apps/users/utils.rs:45:17 | 45 | .filter(id.eq(id)) | ^^^^^^^^^ the trait `diesel::expression::NonAggregate` is not implemented for `bool` | = note: required because of the requirements on the impl of `diesel::query_dsl::filter_dsl::FilterDsl<bool>` for

diesel::query_builder::SelectStatement<schema::confirmations::table>

 error[E0277]: the trait bound `diesel::query_builder::SelectStatement<schema::confirmations::table,

柴油::query_builder::select_clause::DefaultSelectClause、diesel::query_builder::distinct_clause::NoDistinctClause、diesel::query_builder::where_clause::WhereClause>：diesel::query_dsl::filter_dsl::FilterDsl< > is not satisfied --> src/apps/users/utils.rs:46:10 | 46 | .filter(email.eq(email)) | ^^^^^^ the trait is not satisfied --> src/apps/users/utils.rs:46:10 | 46 | .filter(email.eq(email)) | ^^^^^^ the trait is not satisfied --> src/apps/users/utils.rs:46:10 | 46 | .filter(email.eq(email)) | ^^^^^^ the trait diesel::query_dsl::filter_dsl::FilterDsl< > is not implemented for diesel::query_builder::SelectStatement<schema::confirmations::table,diesel::query_builder::select_clause::DefaultSelectClause 實現，diesel::query_builder::distinct_clause::NoDistinctClause，diesel::query_builder::where_clause::WhereClause>` | = 幫助：找到以下實現：<diesel::query_builder::SelectStatement<F, S, D, W, O, L, Of, G, LC> asdiesel::query_dsl::filter_dsl::FilterDsl>

 error: aborting due to 3 previous errors

有人知道如何解決這個錯誤嗎？ Cargo.toml 中的依賴項：

[dependencies]
actix-web = "3.1.0"
actix-rt = "1.1.1"
diesel = { version = "1.4.5", features = ["postgres", "uuidv07", "r2d2", "chrono"] }
r2d2 = "0.8.9"
derive_more = "0.99.11"
bson = "1.1.0"
lazy_static = "1.4.0"
serde = { version = "1.0", features = ["derive"] }
serde_json = "1.0.59"
jsonwebtoken = "7.2.0"
envfile = "0.2.1"
env_logger = "0.8.1"
chrono = { version = "0.4.19", features = ["serde"] }
rust-crypto = "0.2.36"
uuid = { version = "0.8.1", features = ["serde", "v4"] }
futures = "0.3.7"
lettre = { git = "https://github.com/lettre/lettre" }

Answer 1

您將id以及email與他們自己進行比較。 您想要的是將數據庫字段的值與代碼中的值進行比較。

對於柴油，這通常意味着您需要導入架構，如下所示：

use schema::confirmation;

// ..
.filter(confirmation::id.eq(id))
// ..

還可以查看一些示例的文檔： https ://diesel.rs/guides/getting-started/

---

與這個問題無關，你的id不是唯一的嗎？ 如果是這樣，您還可以使用find方法，該方法允許您按主鍵進行搜索。

哦，還有，你不需要使用filter兩次。 有一個方法.and允許你像這樣寫一個查詢： schema::id.eq(id).and(schema::email.eq(email))