coraline 1.4.1

Use Pydantic Models to handle AWS DynamoDB tables

Welcome to Coraline

Coraline is a Python library that provides a seamless integration between Pydantic models and AWS DynamoDB tables. It allows you to define your data models using Pydantic's powerful validation system and easily map them to DynamoDB tables.

Features

• Define DynamoDB tables using Pydantic models
• Automatic table creation and management
• Type validation and conversion
• Support for complex data types
• Easy configuration of AWS credentials
• Simplified CRUD operations

Installation

# Basic installation
pip install coraline

# With boto3 dependency
pip install coraline[boto]

Documentation

Architecture

graph TD
    A[Pydantic Model] -->|Extends| B[CoralModel]
    B -->|Creates/Manages| C[DynamoDB Table]
    B -->|Validates| D[Data]
    D -->|Stored in| C
    E[AWS Credentials] -->|Configure| B
    F[CoralConfig] -->|Configure| B

---

Quick Start

Define Your Model

import uuid
from enum import Enum
from coraline import CoralModel, KeyField, HashType
from pydantic import SecretStr, Field


class UserType(Enum):
    USER = "USER"
    ADMIN = "ADMIN"


class Users(CoralModel):
    user_id: uuid.UUID = KeyField(
        default=lambda: uuid.uuid4(),
        hash_key=HashType.HASH,
        alias="userId"
    )
    user_type: UserType = KeyField(
        ...,
        hash_type=HashType.RANGE,
        alias="userType"
    )
    name: str
    age: int = Field(..., gt=0)
    password: SecretStr


# Create the table if it doesn't exist
Users.get_or_create_table()

# Create and save a new user
new_user = Users(
    name="John Doe",
    user_type=UserType.USER,
    age=30,
    password="123456"
)
new_user.save()

This example:

1. Defines a Users model that extends CoralModel
2. Creates a DynamoDB table named Users with:
   • PAY_PER_REQUEST billing mode (default)
   • userId (String) as the Hash Key
   • userType (String) as the Range Key
   • Additional fields: name (String), age (Number), and password (String)
3. Creates and saves a new user record to the table

Table Configuration

Use the CoralConfig class to customize your DynamoDB table settings.

import uuid
from enum import Enum
from coraline import (
    CoralModel,
    KeyField,
    HashType,
    CoralConfig,
    BillingMode,
    TableClass
)
from pydantic import SecretStr, Field


class UserType(Enum):
    USER = "USER"
    ADMIN = "ADMIN"


def to_camel(string: str) -> str:
    """Convert snake_case to camelCase"""
    return ''.join(word.capitalize() for word in string.split('_'))


# CoralModel is a subclass of Pydantic's BaseModel
class Users(CoralModel):
    # CoralConfig is a subclass of Pydantic's ConfigDict
    model_config = CoralConfig(
        # Custom table name (default is the class name)
        table_name="MyUsers",

        # Set billing mode to PROVISIONED (default is PAY_PER_REQUEST)
        billing_mode=BillingMode.PROVISIONED,
        read_capacity_units=5,
        write_capacity_units=5,

        # Convert field names to camelCase in DynamoDB
        alias_generator=to_camel,

        # Prevent fields from being excluded when None
        protect_from_exclusion=True,

        # Set table storage class
        table_class=TableClass.STANDARD_INFREQUENT_ACCESS,

        # Add any additional parameters accepted by boto3's create_table
        extra_table_params={
            "Tags": [
                {
                    "Key": "Project",
                    "Value": "MyProject"
                }
            ]
        }
    )

    # KeyField is a subclass of Pydantic's Field
    user_id: uuid.UUID = KeyField(
        default=lambda: uuid.uuid4(),
        hash_key=HashType.HASH
    )
    user_type: UserType = KeyField(
        ...,
        hash_type=HashType.RANGE
    )
    name: str
    age: int = Field(..., gt=0)
    password: SecretStr

Available Configuration Options

Option	Description	Default
table_name	Custom name for the DynamoDB table	Class name
billing_mode	BillingMode.PROVISIONED or BillingMode.PAY_PER_REQUEST	BillingMode.PAY_PER_REQUEST
read_capacity_units	Read capacity units (when using PROVISIONED)	5
write_capacity_units	Write capacity units (when using PROVISIONED)	5
alias_generator	Function to transform field names	None
protect_from_exclusion	Prevent fields from being excluded when None	False
table_class	Storage class for the table	TableClass.STANDARD
extra_table_params	Additional parameters for boto3's create_table	{}

---

AWS Credentials Configuration

Coraline provides multiple ways to configure AWS credentials for connecting to DynamoDB. The library follows a priority order when determining which credentials to use:

1. Class-specific configuration in model_config
2. Coraline environment variables
3. Standard AWS environment variables

Environment Variables

You can set AWS credentials using environment variables:

# Standard AWS environment variables
AWS_REGION="us-east-1"
AWS_ACCESS_KEY_ID="your-access-key"
AWS_SECRET_ACCESS_KEY="your-secret-key"

# Coraline-specific environment variables (take precedence)
CORALINE_AWS_REGION="us-west-2"
CORALINE_AWS_ACCESS_KEY_ID="your-coraline-access-key"
CORALINE_AWS_SECRET_ACCESS_KEY="your-coraline-secret-key"
CORALINE_AWS_ENDPOINT_URL="http://localhost:8000"  # For local development

Model Configuration

You can specify AWS credentials directly in your model configuration:

from coraline import CoralModel, CoralConfig

class Users(CoralModel):
    model_config = CoralConfig(
        # AWS credentials
        aws_region="us-east-1",
        aws_access_key_id="your-access-key",
        aws_secret_access_key="your-secret-key",
        aws_endpoint_url="http://localhost:8000"  # For local development
    )

Using Boto3 Config

For more advanced configuration, you can use a boto3 Config instance:

from botocore.config import Config
from coraline import CoralModel, CoralConfig

# Create a boto3 Config instance
config = Config(
    region_name="us-east-1",
    endpoint_url="http://localhost:8000",
    retries={
        'max_attempts': 10,
        'mode': 'standard'
    }
)

class Users(CoralModel):
    model_config = CoralConfig(
        aws_config=config
    )

Local Development

For local development with DynamoDB Local:

from coraline import CoralModel, CoralConfig

class Users(CoralModel):
    model_config = CoralConfig(
        aws_region="local",
        aws_endpoint_url="http://localhost:8000"
    )

---

Basic Operations

Coraline provides a set of methods to interact with DynamoDB tables. Here are the most common operations:

Table Operations

Create or Get Table

Creates a new table if it doesn't exist, or returns information about the existing table:

# Create the table if it doesn't exist
table_description: dict = Users.get_or_create_table()

# Get the table name (returns "Users" by default, or the custom name if specified)
table_name: str = Users.get_table_name()

Get Table Information

Retrieve detailed information about the table:

# Get basic table information
table_info: dict = Users.get_table_info()

# Include additional describe operations
table_info: dict = Users.get_table_info(
    include=[
        "describe_continuous_backups",
        "describe_time_to_live"
    ]
)

Note: Only describe operations that take just the TableName parameter are supported, such as:

• describe_continuous_backups
• describe_time_to_live
• describe_limits

Operations that require additional parameters (like describe_backup, describe_global_table) are not supported through this method.

Record Operations

Check if a Record Exists

Check if a record exists by providing all hash and range keys:

# Check if a user exists
user_exists: bool = Users.exists(
    user_id="12345678-1234-1234-1234-123456789012",
    user_type=UserType.USER
)

Get a Record

Retrieve a record by providing all hash and range keys:

# Get a user
user: Users = Users.get(
    user_id="12345678-1234-1234-1234-123456789012",
    user_type=UserType.USER
)

# Access user properties
print(f"User name: {user.name}")
print(f"User age: {user.age}")

Create and Save a Record

Create a new record and save it to the table:

# Create a new user
new_user = Users(
    name="John Doe",
    user_type=UserType.USER,
    age=30,
    password="123456"
)

# Save the user to the table
new_user.save()

Update a Record

Update an existing record:

# Get an existing user
user = Users.get(
    user_id="12345678-1234-1234-1234-123456789012",
    user_type=UserType.USER
)

# Update properties
user.name = "Jane Doe"
user.age = 31

# Save the changes
user.save()

Delete a Record

Delete an existing record:

# Get an existing user
user = Users.get(
    user_id="12345678-1234-1234-1234-123456789012",
    user_type=UserType.USER
)

# Delete the user
user.delete()

# You can also use the async version
await user.adelete()

# Verify the user no longer exists
user_exists = Users.exists(
    user_id="12345678-1234-1234-1234-123456789012",
    user_type=UserType.USER
)
assert user_exists is False

Advanced Operations

Using boto3's Client Directly

For operations not covered by Coraline's methods, you can access the boto3 client directly:

# Get the boto3 client
client = Users.get_client()

# Use any boto3 DynamoDB client method
client.create_backup(
    TableName=Users.get_table_name(),
    BackupName="MyBackup"
)

# Or from an instance
user = Users.get(
    user_id="12345678-1234-1234-1234-123456789012",
    user_type=UserType.USER
)
user.get_client().update_time_to_live(
    TableName=user.table_name(),
    TimeToLiveSpecification={
        'Enabled': True,
        'AttributeName': 'ExpirationTime'
    }
)

---

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'feat: add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

Please make sure to update tests as appropriate.

Issues and Support

If something isn't working as expected, don't panic. Get a towel and please open an issue.

License

This project is licensed under the MIT License - see the LICENSE file for details.