Setting Up the Environment
- Install the
RestSharp
library from NuGet, a popular library for making HTTP requests in C#. Execute the following command in your Package Manager Console: Install-Package RestSharp
.
- Ensure that you have access to the USPS API by obtaining the necessary credentials (User ID) from USPS.
Create a Function to Make the API Request
- Create a function that formulates a request to the USPS API. You will utilize the
RestSharp
library to simplify HTTP requests.
using RestSharp;
using System;
public class USPSAddressValidator
{
private readonly string _uspsUserId;
public USPSAddressValidator(string uspsUserId)
{
_uspsUserId = uspsUserId;
}
public string ValidateAddress(string firmName, string address1, string address2, string city, string state, string zip5, string zip4)
{
var client = new RestClient("https://secure.shippingapis.com/ShippingAPI.dll");
var request = new RestRequest(Method.GET);
request.AddParameter("API", "Verify");
request.AddParameter("XML",
$"<AddressValidateRequest USERID=\"{_uspsUserId}\"><Revision>1</Revision><Address ID=\"0\">" +
$"<FirmName>{firmName}</FirmName><Address1>{address1}</Address1><Address2>{address2}</Address2>" +
$"<City>{city}</City><State>{state}</State><Zip5>{zip5}</Zip5><Zip4>{zip4}</Zip4></Address></AddressValidateRequest>");
var response = client.Execute(request);
return response.Content;
}
}
Parse the API Response
- After receiving the response from the USPS API, parse the XML response to extract the validated address components.
using System.Xml;
public Address ParseUSPSResponse(string response)
{
XmlDocument doc = new XmlDocument();
doc.LoadXml(response);
XmlNode addressNode = doc.SelectSingleNode("//Address");
if (addressNode == null)
throw new Exception("Invalid response from USPS API.");
return new Address
{
FirmName = addressNode.SelectSingleNode("FirmName")?.InnerText,
Address1 = addressNode.SelectSingleNode("Address1")?.InnerText,
Address2 = addressNode.SelectSingleNode("Address2")?.InnerText,
City = addressNode.SelectSingleNode("City")?.InnerText,
State = addressNode.SelectSingleNode("State")?.InnerText,
Zip5 = addressNode.SelectSingleNode("Zip5")?.InnerText,
Zip4 = addressNode.SelectSingleNode("Zip4")?.InnerText
};
}
Handle Errors and Edge Cases
- Ensure that your code gracefully handles errors from the API, such as malformed input or connectivity issues.
- Implement retry logic for network-related issues or consider caching API responses to reduce redundant checks.
- Employ exception handling around API calls and XML parsing to manage unexpected scenarios smoothly.
Integrate and Test the Solution
- Integrate the address validation into your application where address validation is necessary. Ensure seamless communication between components.
- Create unit tests using frameworks like NUnit or xUnit to validate the robustness and correctness of your address validation logic.
- Verify your implementation with various sample addresses to check for completeness and correctness of the API response parsing.