AWS Clean DynamoDB Store

clean_dynamodb_store is a Rust library designed to follow clean architecture principles, offering a straightforward and efficient DynamoDB store implementation. It simplifies interactions with AWS DynamoDB, making it easier to perform common database operations such as inserting and deleting items in a DynamoDB table.

Features

• Complete CRUD Operations - Put, Get, Delete, Update with type-safe and low-level APIs
• Advanced Querying - Query and Scan operations with filter expressions
• Batch Operations - Efficient batch reads and writes with automatic chunking
• Type-safe API - Work with your own Rust structs using serde
• Efficient client reuse - Following AWS SDK best practices
• Optimized for AWS Lambda - Minimal cold start overhead
• Dual API - High-level type-safe methods + low-level HashMap methods
• Full serde support - Flattening, enums, custom serialization
• Update Expressions - Partial updates with SET, ADD, REMOVE, DELETE
• Pagination Support - Query and Scan with last_evaluated_key
• Input validation - Table names and items/keys
• Custom error types - Better error handling with thiserror
• Clean architecture - Designed with SOLID principles in mind

Prerequisites

Before you begin, ensure you have met the following requirements:

• Rust 2024 edition or later
• AWS account and configured AWS CLI or environment variables for AWS access

Installation

Add clean_dynamodb_store to your Cargo.toml:

[dependencies]
clean_dynamodb_store = "0.1.0"

Usage

Create a DynamoDbStore once and reuse it across operations for optimal performance.

Type-Safe API (Recommended)

Work with your own structs using serde - no manual AttributeValue construction needed:

use clean_dynamodb_store::DynamoDbStore;
use serde::{Serialize, Deserialize};

#[derive(Serialize, Deserialize)]
struct User {
    id: String,
    name: String,
    age: u32,
}

#[derive(Serialize)]
struct UserKey {
    id: String,
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Create store once, reuse many times
    let store = DynamoDbStore::new().await?;

    // Put an item
    let user = User {
        id: "user123".to_string(),
        name: "John Doe".to_string(),
        age: 30,
    };
    store.put("users", &user).await?;

    // Get an item
    let key = UserKey { id: "user123".to_string() };
    let user: Option<User> = store.get("users", &key).await?;

    if let Some(user) = user {
        println!("Found user: {} (age {})", user.name, user.age);
    }

    // Delete an item
    store.delete("users", &key).await?;

    Ok(())
}

Table-Scoped API (Repository Pattern)

For implementing the repository pattern or working extensively with specific tables, you can create table-bound stores:

use clean_dynamodb_store::DynamoDbStore;
use serde::{Serialize, Deserialize};

#[derive(Serialize, Deserialize)]
struct User {
    id: String,
    name: String,
}

#[derive(Serialize)]
struct UserKey {
    id: String,
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let store = DynamoDbStore::new().await?;

    // Create table-bound stores - great for repository pattern
    let users = store.for_table("users");
    let orders = store.for_table("orders");

    // Use without passing table name on each call
    let user = User {
        id: "user123".to_string(),
        name: "John Doe".to_string(),
    };
    users.put(&user).await?;

    let key = UserKey { id: "user123".to_string() };
    let user: Option<User> = users.get(&key).await?;

    users.delete(&key).await?;

    Ok(())
}

When to use table-scoped stores:

• Implementing repository pattern (one repository per entity/table)
• Building domain models with clean architecture principles
• Working extensively with specific tables
• Want cleaner method signatures without table name repetition

Low-Level API

For advanced use cases, you can work directly with DynamoDB's AttributeValue types:

use clean_dynamodb_store::DynamoDbStore;
use aws_sdk_dynamodb::types::AttributeValue;
use std::collections::HashMap;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let store = DynamoDbStore::new().await?;

    // Put an item
    let mut item = HashMap::new();
    item.insert("id".to_string(), AttributeValue::S("user123".to_string()));
    item.insert("name".to_string(), AttributeValue::S("John Doe".to_string()));
    store.put_item("users", item).await?;

    // Delete an item
    let mut key = HashMap::new();
    key.insert("id".to_string(), AttributeValue::S("user123".to_string()));
    store.delete_item("users", key).await?;

    Ok(())
}

Update Operations

For partial item updates without replacing the entire item:

use clean_dynamodb_store::DynamoDbStore;
use aws_sdk_dynamodb::types::AttributeValue;
use serde::Serialize;
use std::collections::HashMap;

#[derive(Serialize)]
struct UserKey {
    id: String,
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let store = DynamoDbStore::new().await?;

    let key = UserKey { id: "user123".into() };

    // Update specific attributes using update expressions
    let update_expression = "SET age = :age, #n = :name".to_string();

    let mut values = HashMap::new();
    values.insert(":age".to_string(), AttributeValue::N("31".to_string()));
    values.insert(":name".to_string(), AttributeValue::S("John Updated".to_string()));

    let mut names = HashMap::new();
    names.insert("#n".to_string(), "name".to_string()); // 'name' is a reserved keyword

    store.update("users", &key, update_expression, Some(values), Some(names)).await?;

    Ok(())
}

Update expression actions:

• SET - Add or update attributes
• REMOVE - Delete attributes
• ADD - Increment numbers or add to sets
• DELETE - Remove from sets

Query Operations

Efficiently retrieve items by partition key (and optional sort key):

use clean_dynamodb_store::DynamoDbStore;
use aws_sdk_dynamodb::types::AttributeValue;
use serde::Deserialize;
use std::collections::HashMap;

#[derive(Deserialize)]
struct Order {
    user_id: String,
    order_id: String,
    total: f64,
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let store = DynamoDbStore::new().await?;

    // Query all orders for a specific user
    let key_condition = "user_id = :user_id".to_string();

    let mut values = HashMap::new();
    values.insert(":user_id".to_string(), AttributeValue::S("user123".to_string()));

    let result = store.query::<Order>("orders", key_condition, values, None).await?;

    println!("Found {} orders", result.count);
    for order in result.items {
        println!("Order {}: ${}", order.order_id, order.total);
    }

    // Handle pagination if needed
    if let Some(last_key) = result.last_evaluated_key {
        // Use last_key for next query
    }

    Ok(())
}

Scan Operations

Scan entire table (use sparingly, prefer Query when possible):

use clean_dynamodb_store::DynamoDbStore;
use aws_sdk_dynamodb::types::AttributeValue;
use serde::Deserialize;
use std::collections::HashMap;

#[derive(Deserialize)]
struct User {
    id: String,
    name: String,
    age: u32,
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let store = DynamoDbStore::new().await?;

    // Scan with filter
    let filter = Some("age > :min_age".to_string());

    let mut values = HashMap::new();
    values.insert(":min_age".to_string(), AttributeValue::N("18".to_string()));

    let result = store.scan::<User>("users", filter, Some(values), None).await?;

    println!("Found {} users (scanned {})", result.count, result.scanned_count);

    Ok(())
}

Batch Operations

Efficiently write or read large numbers of items using batch operations. The library automatically handles chunking and retries with exponential backoff.

Batch Write

For writing large numbers of items, batch operations chunk into groups of 25 (DynamoDB's BatchWriteItem limit):

use clean_dynamodb_store::DynamoDbStore;
use serde::{Serialize, Deserialize};

#[derive(Serialize, Deserialize)]
struct User {
    id: String,
    name: String,
    age: u32,
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let store = DynamoDbStore::new().await?;

    // Create 1000 users
    let users: Vec<User> = (0..1000)
        .map(|i| User {
            id: format!("user{}", i),
            name: format!("User {}", i),
            age: 20 + (i % 50),
        })
        .collect();

    // Batch write - automatically chunks into groups of 25 and retries failures
    let result = store.batch_put("users", &users).await?;

    println!("Successfully wrote {} items", result.successful);
    if result.failed > 0 {
        println!("Failed to write {} items", result.failed);
        for failed in &result.failed_items {
            println!("  Error: {}", failed.error);
        }
    }

    Ok(())
}

Batch Get

For retrieving large numbers of items, batch operations chunk into groups of 100 (DynamoDB's BatchGetItem limit):

use clean_dynamodb_store::DynamoDbStore;
use serde::{Serialize, Deserialize};

#[derive(Serialize)]
struct UserKey {
    id: String,
}

#[derive(Deserialize)]
struct User {
    id: String,
    name: String,
    age: u32,
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let store = DynamoDbStore::new().await?;

    // Create 250 keys to retrieve
    let keys: Vec<UserKey> = (0..250)
        .map(|i| UserKey {
            id: format!("user{}", i),
        })
        .collect();

    // Batch get - automatically chunks into groups of 100 and retries failures
    let result = store.batch_get::<UserKey, User>("users", &keys).await?;

    println!("Successfully retrieved {} items", result.successful);
    for user in &result.items {
        println!("User: {} (age {})", user.name, user.age);
    }

    if result.failed > 0 {
        println!("Failed to retrieve {} keys", result.failed);
    }

    Ok(())
}

Batch operations features:

• Automatic chunking (25 items for write, 100 for get)
• Exponential backoff retry for throttled requests (up to 3 retries)
• Detailed success/failure reporting
• Works with both type-safe API and table-scoped stores

AWS Lambda Usage

For AWS Lambda functions, initialize the store in main() to reuse the client across warm invocations:

use clean_dynamodb_store::DynamoDbStore;
use serde::{Serialize, Deserialize};

#[derive(Serialize, Deserialize)]
struct User {
    id: String,
    name: String,
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Initialize once during cold start
    let store = DynamoDbStore::new().await?;

    // Pass to handler - reused across warm invocations
    lambda_runtime::run(service_fn(|event| handler(event, &store))).await
}

async fn handler(
    event: Event,
    store: &DynamoDbStore,
) -> Result<Response, Box<dyn std::error::Error>> {
    // Use store with type-safe API - no client creation overhead!
    let user = User {
        id: event.id,
        name: event.name,
    };
    store.put("users", &user).await?;

    Ok(Response::success())
}

License

Distributed under the MIT License. See LICENSE for more information.

Contact

Ivan Videnovic - videnovici@yahoo.com