dataflow/README.md

Dataflow

A simple data transformation tool for importing, cleaning, and standardizing data from various sources.

What It Does

Dataflow helps you:

1. Import CSV data with automatic deduplication
2. Transform data using regex rules to extract meaningful information
3. Map extracted values to standardized output
4. Query the transformed data via a web UI or REST API

Perfect for cleaning up messy data like bank transactions, product lists, or any repetitive data that needs normalization.

Core Concepts

1. Sources

Define where data comes from and how to deduplicate it.

Example: Bank transactions deduplicated by date + amount + description

2. Rules

Extract information using regex patterns (extract or replace modes).

Example: Extract merchant name from transaction description

3. Mappings

Map extracted values to clean, standardized output.

Example: "DISCOUNT DRUG MART 32" → {"vendor": "Discount Drug Mart", "category": "Healthcare"}

Architecture

• Database: PostgreSQL with JSONB for flexible data storage
• API: Node.js/Express REST API
• UI: React SPA served from public/
• Auth: HTTP Basic auth (configured in .env)

Design Principles

• Simple & Clear - Easy to understand what's happening
• Explicit - No hidden magic or complex triggers
• Flexible - Handle varying data formats without schema changes

Getting Started

Prerequisites

• PostgreSQL 12+
• Node.js 16+
• Python 3 (for manage.py)

Installation

1. Install Node dependencies:

npm install

2. Run the management script to configure and deploy everything:

python3 manage.py

For development with auto-reload:

npm run dev

The UI is available at http://localhost:3000. The API is at http://localhost:3000/api.

Management Script (manage.py)

manage.py is an interactive tool for configuring, deploying, and managing the service. Run it and choose from the numbered menu:

python3 manage.py

#	Action
1	Database configuration — create/update .env, optionally create the PostgreSQL user/database, and deploy schema + functions
2	Redeploy schema only (database/schema.sql) — drops and recreates all tables
3	Redeploy SQL functions only (database/queries/)
4	Build UI (ui/ → public/)
5	Set up nginx reverse proxy (HTTP or HTTPS via certbot)
6	Install systemd service unit (dataflow.service)
7	Start / restart dataflow.service
8	Stop dataflow.service
9	Set login credentials (LOGIN_USER / LOGIN_PASSWORD_HASH in .env)

The status screen at the top of the menu shows the current state of each component (database connection, schema, UI build, service, nginx).

Typical first-time setup: run options 1 → 4 → 9 → 6 → 7 (→ 5 if you want nginx).

API Reference

All /api routes require HTTP Basic authentication.

Sources — /api/sources

Method	Path	Description
GET	/api/sources	List all sources
POST	/api/sources	Create a source
GET	/api/sources/:name	Get a source
PUT	/api/sources/:name	Update a source
DELETE	/api/sources/:name	Delete a source
POST	/api/sources/suggest	Suggest source definition from CSV upload
POST	/api/sources/:name/import	Import CSV data
GET	/api/sources/:name/import-log	View import history
POST	/api/sources/:name/transform	Apply rules and mappings to records
POST	/api/sources/:name/reprocess	Re-transform all records
GET	/api/sources/:name/fields	List all known field names
GET	/api/sources/:name/stats	Get record and mapping counts
POST	/api/sources/:name/view	Generate output view
GET	/api/sources/:name/view-data	Query output view (paginated, sortable)

Rules — /api/rules

Method	Path	Description
GET	/api/rules/source/:source_name	List rules for a source
POST	/api/rules	Create a rule
GET	/api/rules/:id	Get a rule
PUT	/api/rules/:id	Update a rule
DELETE	/api/rules/:id	Delete a rule
GET	/api/rules/preview	Preview a pattern against real records (ad-hoc)
GET	/api/rules/:id/test	Test a saved rule against real records

Mappings — /api/mappings

Method	Path	Description
GET	/api/mappings/source/:source_name	List mappings
POST	/api/mappings	Create a mapping
POST	/api/mappings/bulk	Bulk create/update mappings
GET	/api/mappings/:id	Get a mapping
PUT	/api/mappings/:id	Update a mapping
DELETE	/api/mappings/:id	Delete a mapping
GET	/api/mappings/source/:source_name/unmapped	Get values with no mapping yet
GET	/api/mappings/source/:source_name/all-values	All extracted values with counts
GET	/api/mappings/source/:source_name/counts	Record counts for existing mappings
GET	/api/mappings/source/:source_name/export.tsv	Export values as TSV
POST	/api/mappings/source/:source_name/import-csv	Import mappings from TSV

Records — /api/records

Method	Path	Description
GET	/api/records/source/:source_name	List records (paginated)
GET	/api/records/:id	Get a single record
POST	/api/records/search	Search records
DELETE	/api/records/:id	Delete a record
DELETE	/api/records/source/:source_name/all	Delete all records for a source

Typical Workflow

1. Create a source (POST /api/sources)
2. Import CSV data (POST /api/sources/:name/import)
3. Create transformation rules (POST /api/rules)
4. Preview rules against real data (GET /api/rules/preview)
5. Apply transformations (POST /api/sources/:name/transform)
6. Review unmapped values (GET /api/mappings/source/:name/unmapped)
7. Add mappings (POST /api/mappings or bulk import via TSV)
8. Reprocess to apply new mappings (POST /api/sources/:name/reprocess)
9. Query results (GET /api/sources/:name/view-data)

See examples/GETTING_STARTED.md for a complete walkthrough with curl examples.

Project Structure

dataflow/
├── database/
│   ├── schema.sql         # Table definitions
│   └── functions.sql      # Import/transform/query functions
├── api/
│   ├── server.js          # Express server
│   ├── middleware/
│   │   └── auth.js        # Basic auth middleware
│   ├── lib/
│   │   └── sql.js         # SQL literal helpers
│   └── routes/
│       ├── sources.js
│       ├── rules.js
│       ├── mappings.js
│       └── records.js
├── public/                # Built React UI (served as static files)
├── examples/
│   ├── GETTING_STARTED.md
│   └── bank_transactions.csv
└── .env.example

License

MIT