DynamoDB CRUD Operations in C#

Perform type-safe Create, Read, Update, and Delete operations on DynamoDB using FluentDynamoDB. This guide demonstrates the three API patterns available: Lambda/Fluent (recommended), String Formatted, and Manual Builder.

Lambda/Fluent

Create (Put)

var user = new User
{
    UserId = "user123",
    Email = "john@example.com",
    Name = "John Doe"
};

// Simple put
await table.Users.PutAsync(user);

// Conditional put (prevent overwrite)
await table.Users.Put(user)
    .Where(x => x.UserId.AttributeNotExists())
    .PutAsync();

Read (Get)

// Simple get
var user = await table.Users.GetAsync("user123");

// Get with composite key
var order = await table.Orders.GetAsync("customer123", "order456");

// Consistent read
var response = await table.Users.Get("user123")
    .UsingConsistentRead()
    .GetItemAsync();

Update

// Update specific attributes
await table.Users.Update("user123")
    .Set(x => new UserUpdateModel 
    { 
        Name = "Jane Doe",
        UpdatedAt = DateTime.UtcNow
    })
    .UpdateAsync();

// Conditional update
await table.Users.Update("user123")
    .Where(x => x.Status == "active")
    .Set(x => new UserUpdateModel { Name = "Jane Doe" })
    .UpdateAsync();

// Increment a counter
await table.Users.Update("user123")
    .Set(x => new UserUpdateModel { LoginCount = x.LoginCount.Add(1) })
    .UpdateAsync();

Delete

// Simple delete
await table.Users.DeleteAsync("user123");

// Conditional delete
await table.Users.Delete("user123")
    .Where(x => x.Status == "inactive")
    .DeleteAsync();

// Delete with composite key
await table.Orders.DeleteAsync("customer123", "order456");

String Formatted

Create (Put)

var user = new User
{
    UserId = "user123",
    Email = "john@example.com",
    Name = "John Doe"
};

// Simple put
await table.Users.PutAsync(user);

// Conditional put (prevent overwrite)
await table.Users.Put(user)
    .Where($"attribute_not_exists({User.Fields.UserId})")
    .PutAsync();

Read (Get)

// Simple get
var user = await table.Users.GetAsync("user123");

// Get with composite key
var order = await table.Orders.GetAsync("customer123", "order456");

// Get with projection
var response = await table.Users.Get("user123")
    .WithProjection($"{User.Fields.Name}, {User.Fields.Email}")
    .GetItemAsync();

Update

// Update specific attributes
await table.Users.Update("user123")
    .Set($"SET {User.Fields.Name} = {{0}}, {User.Fields.Email} = {{1}}", 
         "Jane Doe", 
         "jane@example.com")
    .UpdateAsync();

// Conditional update
await table.Users.Update("user123")
    .Where($"{User.Fields.Status} = {{0}}", "active")
    .Set($"SET {User.Fields.Name} = {{0}}", "Jane Doe")
    .UpdateAsync();

// Increment a counter
await table.Users.Update("user123")
    .Set($"ADD {User.Fields.LoginCount} {{0}}", 1)
    .UpdateAsync();

Delete

// Simple delete
await table.Users.DeleteAsync("user123");

// Conditional delete
await table.Users.Delete("user123")
    .Where($"{User.Fields.Status} = {{0}}", "inactive")
    .DeleteAsync();

// Delete with composite key
await table.Orders.DeleteAsync("customer123", "order456");

Manual Builder

Create (Put)

var user = new User
{
    UserId = "user123",
    Email = "john@example.com",
    Name = "John Doe"
};

// Simple put
await table.Users.PutAsync(user);

// Conditional put (prevent overwrite)
await table.Users.Put(user)
    .Where("attribute_not_exists(#pk)")
    .WithAttribute("#pk", "pk")
    .PutAsync();

Read (Get)

// Simple get
var user = await table.Users.GetAsync("user123");

// Get with composite key
var order = await table.Orders.GetAsync("customer123", "order456");

// Get with projection
var response = await table.Users.Get("user123")
    .WithProjection("#name, #email")
    .WithAttribute("#name", "name")
    .WithAttribute("#email", "email")
    .GetItemAsync();

Update

// Update specific attributes
await table.Users.Update("user123")
    .Set("SET #name = :name, #email = :email")
    .WithAttribute("#name", "name")
    .WithAttribute("#email", "email")
    .WithValue(":name", "Jane Doe")
    .WithValue(":email", "jane@example.com")
    .UpdateAsync();

// Conditional update
await table.Users.Update("user123")
    .Where("#status = :status")
    .WithAttribute("#status", "status")
    .WithValue(":status", "active")
    .Set("SET #name = :name")
    .WithAttribute("#name", "name")
    .WithValue(":name", "Jane Doe")
    .UpdateAsync();

// Increment a counter
await table.Users.Update("user123")
    .Set("ADD #count :inc")
    .WithAttribute("#count", "login_count")
    .WithValue(":inc", 1)
    .UpdateAsync();

Delete

// Simple delete
await table.Users.DeleteAsync("user123");

// Conditional delete
await table.Users.Delete("user123")
    .Where("#status = :status")
    .WithAttribute("#status", "status")
    .WithValue(":status", "inactive")
    .DeleteAsync();

// Delete with composite key
await table.Orders.DeleteAsync("customer123", "order456");

Entity Definition

All examples above use this entity definition:

[DynamoDbTable("users")]
public partial class User
{
    [PartitionKey]
    [DynamoDbAttribute("pk")]
    public string UserId { get; set; } = string.Empty;
    
    [DynamoDbAttribute("email")]
    public string Email { get; set; } = string.Empty;
    
    [DynamoDbAttribute("name")]
    public string Name { get; set; } = string.Empty;
    
    [DynamoDbAttribute("status")]
    public string Status { get; set; } = "active";
    
    [DynamoDbAttribute("login_count")]
    public int LoginCount { get; set; }
}

Learn More

• CRUD Operations Guide - Complete CRUD operations reference
• Entity Definition - How to define DynamoDB entities
• Query and Scan - Query patterns for retrieving multiple items
• Transactions - Atomic operations across multiple items