Post to api with parameters-CodePudding

Trying to call an api :"https://api.postcodes.io/postcodes/" Is a post-call with this structure:

{
  "postcodes" : ["PR3 0SG", "M45 6GN", "EX165BL"]
}

What is the best practice to create the array of postcodes and how to send them? My code:

List<string> test = new List<string>();
test.Add("OX49 5NU");
test.Add("M32 0JG");
test.Add("NE30 1DP");

var requestString = string.Join(",", test.ToArray());

var queryParams = new Dictionary<string, string>()
{
    { "postcodes", requestString }
};

var s = queryParams.ToString();
var data = new StringContent(queryParams.ToString(), Encoding.UTF8, "application/json");
var uri = "https://api.postcodes.io/postcodes/";
var httpClient = new HttpClient();
var response = await httpClient.PostAsync(uri, data);

Not working.

Kind regards /Rudy

CodePudding user response：

You shouldn't be using .ToString() at all and rely on the wonderful JSON serialization available in .Net.

    List<string> postcodes = new List<string>
    {
        "OX49 5NU",
        "M32 0JG",
        "NE30 1DP"
    };

    var json = System.Text.Json.JsonSerializer.Serialize(new { postcodes });
    var content = new StringContent(json, Encoding.UTF8, "application/json");
    
    using var httpClient = new HttpClient();

    var uri = "https://api.postcodes.io/postcodes/";
    var response = await httpClient.PostAsync(uri, content);

new { postcodes } creates an anonymous type with a single property named postcodes consisting of the list of postcodes.

Note also the using on httpClient. For a trivial example it probably doesn't matter but you should at least be disposing of the httpClient properly.

UPDATE
As @marsze pointed out, it's usually best to use IHttpClientFactory, calling CreateClient() when you need a HttpClient this will allow .Net to pool HttpClients that can be reused without consuming additional resources.

CodePudding user response：

Your request has to be in JSON format. For that, you might want to write your own DTO, somewhat like this:

class PostcodeBody
{
    public List<string> Postcodes { get; } = new List<string>();
}

And then serialize it using the JSON serializer of your choice:

var body = new PostcodeBody();
body.Postcodes.Add("OX49 5NU");
body.Postcodes.Add("M32 0JG");
body.Postcodes.Add("NE30 1DP");
var data = new StringContent(JsonConvert.SerializeObject(body), Encoding.UTF8, "application/json");