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Data Broker Core

The Data Broker Core is a collection of common components used by other Data Broker packages.

Background

The U.S. Department of the Treasury is building a suite of open-source tools to help federal agencies comply with the DATA Act and to deliver the resulting standardized federal spending information back to agencies and to the public.

For more information about the Data Broker codebase, please visit this repository's main README.

Data Broker Core Database Reference

The Data broker uses a single database (called data_broker) to track broker users, jobs and submissions, validation errors, and domain information needed to run data validations.

Data Broker Core Project Layout

The Data Broker Core is a collection of common components used by other Data Broker packages. The directory structure is as follows:

dataactcore/
├── aws/            (Common AWS functions)
├── migrations/     (Alembic migration scripts)
├── credentials/    (Database credentials)
├── models/         (ORM models)
├── scripts/        (Utility and database setup scripts)
└── utils/          (JSON helper objects)

AWS

The aws/ folder contains all of the common code that uses AWS Boto SDK, which requires the AWS CLI to function correctly. The installation instructions for the AWS CLI can be found in the Data Broker installation guide.

Migrations

This contains the code for running migrations to different alembic versions of the database, and contains the version history for all alembic migrations.

Models

The models/ folder contains the object-relational mapping (ORM) definition for all models used in the Data Broker project. When a new table is needed, a new object needs to be defined using the SQLAlchemy object notation. For example, a table with a single column of text and a primary key should be defined as follows.

from sqlalchemy import Column, Integer, Text
from sqlalchemy.ext.declarative import declarative_base

Base = declarative_base()
class ExampleTable(Base):
    __tablename__ = 'example_table'

    example_table_id = Column(Integer, primary_key=True)
    text_field = Column(Text)

Note that all new ORM objects must inherit from the declarative_base object and have the __tablename__ field set. For consistency, field and tables names should be in all lower case, separated by _ between words.

Additional fields exist on some of the models to enable the automatic population of foreign key relationships. These fields use the relationship function to signify a mapping to another table. More information on SQLAlchemy ORM objects can be found on the official website.

Scripts

The scripts/ folder contains various python scripts used in the Data Broker backend install process as well as various utility scripts.

Utils

The utils/ folder contains common REST requests and error handling objects. These provide a common way for other broker components to handle requests.

The RequestDictionary class is used throughout the Data Broker repository to provide a seamless method to access both the JSON Body and POST FormData from a REST request. For example, if the following JSON was sent to a REST endpoint:

{
  "data" : "value"
}

It would be accessed by:

    requestDictionary = RequestDictionary(request)
    value = requestDictionary.get_value("data")

The JsonResponse object contains methods for automatically encoding a JSON response from a REST request. Users are able to pass dictionary objects that will be automatically converted to JSON with the correct application headers added.

In addition, the static error method will auto create a JSON response with the current exception stack trace encoded. This is useful in the development environment, but should be disabled in production by setting the debug configuration to false.