[Rust Diesel] FAQs - Diesel

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FAQs - Deisel

Diesel is a Safe, Extensible ORM and Query Builder for Rust.

panicked at ‘called Result::unwrap() on an Err value: DeserializationError(UnexpectedNullError)’

Remember to make optional attribute adn column with Option or Nullable.

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// models.rs

use uuid::Uuid;

#[derive(Queryable)]
pub struct Post {
    pub id: i32,

-    pub name: title,
+    pub name: Option<title>,
}
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// schema.rs

table! {
    posts (id) {
        id -> Int4,

-        name -> Varchar,
+        name -> Nullable(Varchar),
    }
}

the trait Queryable<diesel::sql_types::Uuid, _> is not implemented for uuid::Uuid

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// models.rs

use uuid::Uuid;

#[derive(Queryable)]
pub struct Post {
    pub id: Uuid,

    pub name: title,
}
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// schema.rs

table! {
    posts (id) {
        id -> Uuid,

        name -> Varchar,
    }
}
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// repositories.rs

        let connection = pool::establish_connection();
        let results = posts
            .filter(title.eq("title"))
            .limit(5)
            .load::<Post>(&connection).unwrap();

See what’s in your Cargo.lock file and look are uuid package dependencies. Be sure they are using the same versions as uuid::Uuid.

See postgresql - Cannot use UUID as a primary key: Uuid: diesel::Expression is not satisfied - Stack Overflow - https://stackoverflow.com/questions/60441600/cannot-use-uuid-as-a-primary-key-uuid-dieselexpression-is-not-satisfied to learn more.

References

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