🔄 CSV Merger Tool

Go tool for merging two CSV files using composite keys.

✨ Features

• Smart Merging: Combines data from two CSVs using multi-column keys
• Env Configuration: Environment variables for full control
• Safe Overwrite: Default value for unmatched records
• Auto Validation: Checks required columns automatically

⚙️ Prerequisites

• Go 1.16+
• Zerolog Library:

  go get github.com/rs/zerolog

🔧 Configuration (.env)

DATA_OUTPUT_DIR=output        # Output directory
FIRST_CSV=primary.csv        # Path to first CSV
SECOND_CSV=secondary.csv     # Path to second CSV
KEY_COLUMNS_FIRST=id,date    # Key columns from first CSV (comma-separated)
KEY_COLUMNS_SECOND=id,date   # Key columns from second CSV
OVERWRITE_COLUMN=status      # Column to overwrite in first CSV
SOURCE_COLUMN=value          # Source column from second CSV
DEFAULT=undefined            # Default value for unmatched records

🚀 Usage

1. Configure

   .env
2. Run:

go run main.go

3. Output saved to:

output/merged_primary.csv

📌 Example

Primary CSV:

id,date,status
1,2023-01,old
2,2023-02,old

Secondary CSV:

id,date,value
1,2023-01,new
3,2023-03,new

Output:

id,date,status
1,2023-01,new
2,2023-02,undefined

🔄 Processing Flow

graph TD
    A[Primary CSV] --> B[Read Keys]
    C[Secondary CSV] --> D[Create Lookup]
    B --> E[Merge Data]
    D --> E
    E --> F[Generate Merged CSV]

🛑 Troubleshooting

• Missing Columns: Verify header names
• File Not Found: Check

  .env
  paths
• Empty CSV: Validate file contents

📄 License

MIT License - See LICENSE for details.