Transactions

To manage transactions manually you can use db.begin_transaction(), and then the Fluent API to add the operations needed in the transaction.

use firestore::*;
use serde::{Deserialize, Serialize};
#[derive(Debug, Clone, Deserialize, Serialize)]
struct MyTestStructure { some_id: String, some_string: String }
const TEST_COLLECTION_NAME: &str = "test";
async fn example(db: FirestoreDb) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
let mut transaction = db.begin_transaction().await?;

db.fluent()
    .update()
    .fields(paths!(MyTestStructure::{
      some_string
    }))
    .in_col(TEST_COLLECTION_NAME)
    .document_id("test-0")
    .object(&MyTestStructure {
        some_id: format!("test-0"),
        some_string: "UpdatedTest".to_string(),
    })
    .add_to_transaction(&mut transaction)?;

db.fluent()
    .delete()
    .from(TEST_COLLECTION_NAME)
    .document_id("test-5")
    .add_to_transaction(&mut transaction)?;

transaction.commit().await?;
Ok(())
}

You may also execute transactions that automatically retry with exponential backoff using run_transaction.

use firestore::*;
use serde::{Deserialize, Serialize};
#[derive(Debug, Clone, Deserialize, Serialize)]
struct MyTestStructure { test_string: String }
const TEST_COLLECTION_NAME: &str = "test";
const TEST_DOCUMENT_ID: &str = "test_doc_id";
async fn example(db: FirestoreDb) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
db.run_transaction(|db, transaction| {
    Box::pin(async move {
        let mut test_structure: MyTestStructure = db
            .fluent()
            .select()
            .by_id_in(TEST_COLLECTION_NAME)
            .obj()
            .one(TEST_DOCUMENT_ID)
            .await?
            .expect("Missing document");

        // Perform some kind of operation that depends on the state of the document
        test_structure.test_string += "a";

        db.fluent()
            .update()
            .fields(paths!(MyTestStructure::{
             test_string
            }))
            .in_col(TEST_COLLECTION_NAME)
            .document_id(TEST_DOCUMENT_ID)
            .object(&test_structure)
            .add_to_transaction(transaction)?;

        Ok(())
    })
})
.await?;
Ok(())
}

See the complete example available here.

Please note that Firestore doesn’t support creating documents in the transactions (generating document IDs automatically), so you need to use update() to implicitly create documents and specifying your own IDs.