循环调用C# await调用从web中取出JSON数据

Question

I have a method that calls an API with HttpClient and build a list of Customers as IEnumerable<Customer> . The way this API works is that it will return only 100 customers at a time, and will provide another link in the JSON content to fetch again the next 100.

How can I structure this code to iteratively fetch the records until all are fetched and build a large IEnumerable<Customer> and return from this method. It is okay to break this large method to another small one. I don't want a synchronous process.

Task<IEnumerable<Customer>> GetCustomers(string url)
{
  HttpClient client = new HttpClient();
  HttpResponseMessage response = await client.GetAsync(url);
  response.EnsureSuccessStatusCode();
  string responseBody = await response.Content.ReadAsStringAsync();
  
  // TODO: Deserialize responseBody and build a new IEnumerable<Customer>
}

Json:

{
    "nextRecords": "\\customers\\123",
    "customers": [
       {"name": "John Doe"},
       {"name": "Mary Doe"}
    ]
}

Answer 1

From sample JSON the following models are derived.

public class RootObject {
    public string nextRecords { get; set; }
    public IList<Customer> customers { get; set; }
}

public class Customer {
    public string name { get; set; }
}

Getting the result can be done using

HttpClient client = new HttpClient();
async Task<IEnumerable<Customer>> GetCustomers(string url) {
    var result = new List<Customer>();
    do {
        var response = await client.GetAsync(url);

        response.EnsureSuccessStatusCode();

        var body = await response.Content.ReadAsAsync<RootObject>();

        result.AddRange(body.customers);

        url = body.nextRecords;
    } while(!string.IsNullOrWhitespace(url));

    return result;        
}