Error Handling

Understanding API error responses and how to handle them

Error Handling

The Bilanc Metrics API returns standard HTTP status codes to indicate success or failure of an API request.

HTTP Status Codes

Status Code	Description
200 OK	Request successful
400 Bad Request	Invalid request parameters
401 Unauthorized	Authentication failed
403 Forbidden	Insufficient permissions
404 Not Found	Requested resource not found
422 Unprocessable Entity	Request validation failed
429 Too Many Requests	Rate limit exceeded
500 Internal Server Error	Server-side error

Error Response Format

Error responses include a detail message explaining the issue:

{
  "detail": "Error message"
}

For validation errors, the response includes more detailed information about the specific validation issues:

{
  "detail": [
    {
      "loc": ["body", "filters", "start_date"],
      "msg": "field required",
      "type": "value_error.missing"
    },
    {
      "loc": ["body", "date_level"],
      "msg": "value is not a valid enumeration member; permitted: 'day', 'week', 'month', 'quarter', 'year'",
      "type": "type_error.enum",
      "ctx": {
        "enum_values": ["day", "week", "month", "quarter", "year"]
      }
    }
  ]
}

Common Error Scenarios

Authentication Errors

{
  "detail": "Not authenticated"
}

This error occurs when:

• The authentication token is missing
• The authentication token is invalid
• The authentication token has expired

Invalid Parameters

{
  "detail": [
    {
      "loc": ["body", "filters", "start_date"],
      "msg": "invalid date format. Expected format: YYYY-MM-DD",
      "type": "value_error.date"
    }
  ]
}

This error occurs when:

• Required parameters are missing
• Parameters have invalid values
• Parameters have invalid formats

Resource Not Found

{
  "detail": "Metric type 'unknown-metric' not found"
}

This error occurs when:

• The requested metric type doesn’t exist
• The specified resource ID doesn’t exist

Server Errors

{
  "detail": "Internal server error"
}

This error occurs when:

• The server encounters an unexpected condition
• A dependency service is unavailable

Handling Errors in Your Applications

JavaScript Example

const fetchMetrics = async () => {
  try {
    const response = await fetch('https://api.bilanc.co/metrics/cycle-time', {
      method: 'POST',
      headers: {
        'Authorization': 'YOUR_API_KEY',
        'Content-Type': 'application/json'
      },
      body: JSON.stringify({
        filters: {
          repository_id: "123456"
        },
        date_level: "month"
      })
    });
    
    if (!response.ok) {
      const errorData = await response.json();
      
      // Handle different error types
      switch (response.status) {
        case 400:
          console.error('Invalid request parameters:', errorData.detail);
          break;
        case 401:
          console.error('Authentication failed. Please check your API token.');
          break;
        case 429:
          console.error('Rate limit exceeded. Please try again later.');
          break;
        case 500:
          console.error('Server error. Please try again later or contact support.');
          break;
        default:
          console.error('API error:', errorData.detail);
      }
      
      throw new Error(`API error: ${response.status}`);
    }
    
    const data = await response.json();
    return data;
  } catch (error) {
    console.error('Error fetching metrics:', error);
    throw error;
  }
};

Python Example

import requests

def fetch_metrics():
    url = "https://api.bilanc.co/metrics/cycle-time"
    
    headers = {
        "Authorization": "YOUR_API_KEY",
        "Content-Type": "application/json"
    }
    
    payload = {
        "filters": {
            "repositories": [{"repository_name": "my-repo"}]
        },
        "date_level": "month"
    }
    
    try:
        response = requests.post(url, json=payload, headers=headers)
        response.raise_for_status()  # Raise exception for 4XX/5XX responses
        
        return response.json()
    except requests.exceptions.HTTPError as e:
        error_msg = "Unknown error"
        
        if response.headers.get("content-type") == "application/json":
            try:
                error_data = response.json()
                if "detail" in error_data:
                    error_msg = error_data["detail"]
            except:
                pass
        
        # Handle different error types
        if response.status_code == 400:
            print(f"Invalid request parameters: {error_msg}")
        elif response.status_code == 401:
            print("Authentication failed. Please check your API token.")
        elif response.status_code == 429:
            print("Rate limit exceeded. Please try again later.")
        elif response.status_code == 500:
            print("Server error. Please try again later or contact support.")
        else:
            print(f"API error ({response.status_code}): {error_msg}")
        
        raise
    except Exception as e:
        print(f"Error fetching metrics: {str(e)}")
        raise

Best Practices for Error Handling

1. Always check status codes: Don’t assume that a request will succeed.
2. Implement retry logic: For transient errors (429, 500, etc.), implement a backoff strategy.
3. Log detailed error information: Include request details and response information for debugging.
4. Provide user-friendly error messages: Translate API errors into actionable information for users.
5. Handle validation errors gracefully: Parse the detailed validation error messages to help users fix their inputs.
6. Monitor error rates: Set up monitoring to track API errors and patterns.
7. Contact support for persistent issues: For recurring errors, contact Bilanc support with detailed information about the problem.