从 appsettings.json 将多个端点路由添加到 .net 核心控制台应用程序

Question

I'm using .net core 3.1 to build a console app that acts as an event handler API.

The app captures changes to a database and directs those changes to other APIs, in real-time. Updates to "customer" go to "customerAPI", "product" goes to "productAPI" and so on. This means that I have an appsettings.Local.json that looks like this:

 "DBConnectionStrings": {
    "DefaultConnection": "AccountEndpoint=(my account)",
    "SourceDatabaseName": "MyDB",
    "SourceContainerName": "MySource",
    "LeasesContainerName": "MyLease",
    "PartitionKey": "/id"
  },
  "EndpointAPIStrings": {
    "Endpoint1": {
      "EndpointUrl": "https://localhost:7777",
      "Username": "myusername1",
      "Password": "mypassword1",
    "Endpoint2": {
      "EndpointUrl": "https://localhost:8888",
      "Username": "myusername2",
      "Password": "mypassword2",
    "Endpoint3": {
      "EndpointUrl": "https://localhost:9999",
      "Username": "myusername3",
      "Password": "mypassword3"
    ...
    }

I am currently using a crappy method of declaring them as EnvironmentVariables to get them from my Main where the configuration is built to my CallAPI Task.

Main:

public static async Task Main(string[] args)
{
    ...
    IConfiguration configuration = BuildConfiguration(environmentName);
    CosmosClient cosmosClient = BuildCosmosClient(configuration);

    Environment.SetEnvironmentVariable("EndpointUrl", configuration["EndpointAPIStrings:Endpoint1:EndpointURL"]);
    Environment.SetEnvironmentVariable("Username", configuration["EndpointAPIStrings:Endpoint1:Username"]);
    Environment.SetEnvironmentVariable("Password", configuration["EndpointAPIStrings:Endpoint1:Password"]);
    ...
}

Delegate function:

...
if (entityType == "myproduct")
{
    var entity = "products";
    var result = await Task.Run(() => CallAPIAsync(entity, item));
}
...

Task CallAPI:

public static async Task<HttpResponseMessage> CallAPIAsync(string entity, ProcessedItem item)
{
    using (var client = new HttpClient())
    {
        Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
        var endpointUrl = Environment.GetEnvironmentVariable("EndpointUrl");
        var uri = new Uri($"{endpointUrl}/api/{entity}/{item.Id}/propagate");
        string username = Environment.GetEnvironmentVariable("Username");
        string password = Environment.GetEnvironmentVariable("Password");
        ...
    }
}

This obviously only works for the first endpoint and ignores the others.

How can I refactor this to get the values into my CallAPI Task for all EndpointAPIStrings?

Answer 1

You can create a class for it and read the values into that class. Also changing it to a list in the JSON would be good. Steps I would do:

1. Change 'EndpointAPIStrings' into an array:

    { "EndpointAPIStrings":[ { "Id":"Endpoint1", "EndpointUrl":"https://localhost:7777", "Username":"myusername1", "Password":"mypassword1" }, { "Id":"Endpoint2", "EndpointUrl":"https://localhost:8888", "Username":"myusername2", "Password":"mypassword2" }, { "Id":"Endpoint3", "EndpointUrl":"https://localhost:9999", "Username":"myusername3", "Password":"mypassword3" } ] }

2. Create a C# class defining the objects in the JSON array:

    public sealed class EndPoint { public string Id { get; set; } public string EndPointUrl { get; set; } public string Username { get; set; } public string Password { get; set; } }

3. Change data retrieval from the configuration:

    IConfiguration configuration = BuildConfiguration(environmentName); CosmosClient cosmosClient = BuildCosmosClient(configuration); List<EndPoint> endPoints = configuration.GetSection("EndPointAPIStrings").Get<List<EndPoint>>();

---

Now you have all your endpoints in the endPoints variable. You can remove and add properties into the JSON how you like and the only thing you need to do is change the class accordingly. Please note that you need the same names in the JSON and in the C# class in order to get a successful mapping.

Answer 2

I've done this in a Windows Service .net Core 3.1 app, pretty similar. Essentially when you call your IHostBuilder function in program.cs

public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .UseWindowsService()
                .ConfigureLogging(loggerFactory => loggerFactory.AddEventLog())
                .ConfigureServices((hostContext, services) =>
                {
                    services.AddHostedService<Worker>();
                });

You get access to your configuration variables from appsettings.json by default. Which can then be accessed in your main startup or execute function:

private readonly ILogger<Worker> _logger;

private readonly IServiceScopeFactory _serviceScopeFactory;

private readonly IConfiguration _config;

public Worker(ILogger<Worker> logger, IServiceScopeFactory serviceScopeFactory, IConfiguration config)
            {
                _logger = logger;
                _serviceScopeFactory = serviceScopeFactory;
                _config = config;
            }  

And then in your main or execute function:

protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            // Must be a scoped process in order to run correctly
            using var scope = _serviceScopeFactory.CreateScope();
            // Start timer and begin log
            var startTime = DateTime.UtcNow;
            var env = _config.GetValue<string>("ENV");
            var stageTable = _config.GetValue<string>("StageTable");
            var prevTable = _config.GetValue<string>("PrevTable");
            var mainTable = _config.GetValue<string>("MainTable");
            var sqlConnectionString = _config.GetValue<string>("SqlConnString_" + env);
            var excelConnectionString = _config.GetValue<string>("ExcelConnectionString1") +
                                        _config.GetValue<string>("ExcelFilePath_" + env) +
                                        _config.GetValue<string>("ExcelFileName") +
                                        _config.GetValue<string>("ExcelConnectionString2");

With an appsettings.json like:

"ENV": "LOCAL",
"StageTable": "Staging",
"PrevTable": "Previous",
"MainTable": "Courses",