A GraphQL API server for querying bank branch information built with Python, Strawberry GraphQL, and Flask.

• GraphQL API with Strawberry
• Bank and Branch data queries
• CSV data source
• Comprehensive test suite
• Relay-style connections with edges and nodes

• Python 3.8 or higher
• pip (Python package installer)

1. Clone the repository:

   git clone https://github.com/BlackBuck/py-graphql
   cd py-graphql

2. Create a virtual environment (recommended):

   python -m venv venv
   source venv/bin/activate  # On Windows: venv\Scripts\activate

3. Install dependencies:

   pip install -r requirements.txt

Create a CSV file named bank_branches.csv in the root directory with the following columns:

bank_id,bank_name,branch,ifsc,address,city,district,state
1,State Bank of India,Mumbai Main,SBIN0000001,SBI Building Mumbai,Mumbai,Mumbai,Maharashtra
2,HDFC Bank,Delhi Main,HDFC0000001,HDFC Building Delhi,Delhi,Delhi,Delhi
3,ICICI Bank,Bangalore Main,ICIC0000001,ICICI Building Bangalore,Bangalore,Bangalore,Karnataka

Required CSV columns:

• bank_id: Unique identifier for the bank
• bank_name: Name of the bank
• branch: Branch name
• ifsc: IFSC code
• address: Branch address
• city: City name
• district: District name
• state: State name

py-graphql/
├── app.py              # Main GraphQL schema and data loading
├── server.py           # Flask server wrapper
├── app_test.py         # Test suite
├── requirements.txt    # Python dependencies
├── bank_branches.csv   # Your data file
└── README.md          # This file

python server.py

The server will start at http://localhost:5000

• Home page: http://localhost:5000/
• GraphQL endpoint: http://localhost:5000/graphql

For development, you can also run just the GraphQL schema:

python -c "from app import schema; print('Schema loaded successfully')"

URL: POST http://localhost:5000/graphql

query {
  branches {
    edges {
      node {
        branch
        ifsc
        address
        city
        district
        state
        bank {
          id
          name
        }
      }
    }
  }
}

query {
  branches {
    edges {
      node {
        branch
        ifsc
        bank {
          name
        }
      }
    }
  }
}

query {
  branches {
    edges {
      node {
        branch
        city
        district
        state
        bank {
          name
        }
      }
    }
  }
}

curl -X POST http://localhost:5000/graphql \
  -H "Content-Type: application/json" \
  -d '{
    "query": "query { branches { edges { node { branch ifsc bank { name } } } } }"
  }'

import requests

url = "http://localhost:5000/graphql"
query = """
query {
  branches {
    edges {
      node {
        branch
        ifsc
        bank {
          name
        }
      }
    }
  }
}
"""

response = requests.post(url, json={"query": query})
print(response.json())

Run the test suite to ensure everything is working correctly:

# Run all tests
python app_test.py

# Run with verbose output
python app_test.py -v

# Run with pytest (if installed)
pytest app_test.py -v

The test suite includes:

• Schema validation
• Query structure verification
• Data type checking
• Bank name field validation
• Basic functionality tests

To add new queries, modify the Query class in app.py:

@strawberry.type
class Query:
    @strawberry.field
    def branches(self) -> BranchConnection:
        return BranchConnection(edges=[BranchEdge(node=b) for b in BRANCHES])
    
    # Add your new query here
    @strawberry.field
    def branch_by_ifsc(self, ifsc: str) -> Branch:
        for branch in BRANCHES:
            if branch.ifsc == ifsc:
                return branch
        return None

1. Update the CSV file with new columns
2. Modify the Branch or Bank classes in app.py
3. Update the data loading logic
4. Add corresponding tests

1. CSV file not found:

   FileNotFoundError: [Errno 2] No such file or directory: 'bank_branches.csv'
   

   Solution: Make sure bank_branches.csv exists in the root directory.

2. Import errors:

   ModuleNotFoundError: No module named 'strawberry'
   

   Solution: Install dependencies with pip install -r requirements.txt

3. Empty results: If queries return empty results, check:

   • CSV file has data
   • Column names match expected names
   • No encoding issues in CSV file

Run the server in debug mode to see detailed error messages:

export FLASK_DEBUG=1
python server.py

• strawberry-graphql: GraphQL library for Python
• Flask: Web framework
• pandas: Data manipulation library

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Add tests for new functionality
5. Run the test suite
6. Submit a pull request

This project is open source and available under the MIT License.

type Bank {
  id: Int!
  name: String!
}

type Branch {
  branch: String!
  ifsc: String!
  address: String!
  city: String!
  district: String!
  state: String!
  bank: Bank!
}

type BranchEdge {
  node: Branch!
}

type BranchConnection {
  edges: [BranchEdge!]!
}

type Query {
  branches: BranchConnection!
}