part6.md

Adding the firestore logic

Signup

Let's now replace our dummy repository logic by actual queries. To run your program with the emulator, make sure to have FIRESTORE_EMULATOR_HOST defined like so : FIRESTORE_EMULATOR_HOST="localhost:4510" PROJECT_ID=omelettedufromage cargo run.

A naive version of our signup function would look a little bit like this :

    pub async fn signup(
        &self,
        username: String,
        email: String,
        password: String,
    ) -> Result<String, FirestoreError> {
        let user = User {
            id: None,
            username,
            email,
            password,
        };

        let result: Result<User, FirestoreError> = self
            .db
            .fluent()
            .insert()
            .into(COLLECTION_NAME)
            .generate_document_id()
            .object(&user)
            .execute()
            .await;

        match result {
            Ok(user) => Ok(user.id.expect("This should never happen")),
            Err(error) => Err(error),
        }
    }

Note that thanks to the firestore library, and the serde annotation we used earlier, the id field of our struct is automatically filled when we insert the document.

Login

You may have noticed that the return type of login is a little bit more complex that signup. This is because it handles both technical errors, but also possible user mistakes.

A possible implementation could be the following :

    pub async fn login(
        &self,
        username: String,
        password: String,
    ) -> Result<Option<String>, FirestoreError> {
        let user_result: Result<Vec<User>, FirestoreError> = self
            .db
            .fluent()
            .select()
            .from(COLLECTION_NAME)
            .filter(|q| {
                q.for_all({
                    [
                        q.field(path_camel_case!(User::username)).equal(&username),
                        q.field(path_camel_case!(User::password)).equal(&password),
                    ]
                })
            })
            .obj()
            .query()
            .await;

        match user_result {
            Ok(users) if users.len() == 1 => Ok(Some("my_token".to_string())),
            Err(error) => Err(error),
            // No error, but we did not find a user.
            _ => Ok(None),
        }
    }

Now run your program and try it out !

If you wish to see the completed workshop, the code is available on the completed_code branch of this repository.