Send array using HTTPClient PostAsync

Question

I have an array of location points (latitude, longitude, and created_at) that need to be sent up in bulk. However, when I use JsonConvert.SerializeObject() it returns a string which can't be parsed on the server endpoint.

var location_content = new FormUrlEncodedContent(new[] {
    new KeyValuePair<string, string>("access_token", $"{Settings.AuthToken}"),
    new KeyValuePair<string, string>("coordinates", JsonConvert.SerializeObject(locations))
});

var response = await client.PostAsync(users_url + bulk_locations_url, location_content);

The result looks like the following:

{"access_token":"XX","coordinates":"[{\"created_at\":\"2018-03-27T21:36:15.308265\",\"latitude\":XX,\"longitude\":XX},{\"created_at\":\"2018-03-27T22:16:15.894579\",\"latitude\":XX,\"longitude\":XX}]"}

The array of coordinates comes across as one big string, so it looks like :"[{\\"created_at\\": when it should be :[{"created_at": .

So, the server is expecting something like this:

{"access_token":"XX","coordinates":[{\"created_at\":\"2018-03-27T21:36:15.308265\",\"latitude\":XX,\"longitude\":XX},{\"created_at\":\"2018-03-27T22:16:15.894579\",\"latitude\":XX,\"longitude\":XX}]}

Location.cs

public class Location
{
    public DateTime created_at { get; set; }
    public double latitude { get; set; }
    public double longitude { get; set; }

    [PrimaryKey, AutoIncrement, JsonIgnore]
    public int id { get; set; }

    [JsonIgnore]
    public bool uploaded { get; set; }

    public Location()
    {

    }

    public Location(double lat, double lng)
    {
        latitude = lat;
        longitude = lng;

        uploaded = false;
        created_at = DateTime.UtcNow;

        Settings.Latitude = latitude;
        Settings.Longitude = longitude;
    }

    public Location(Position position) : this(position.Latitude, position.Longitude) {}
}

Is there a way to make the key value pairs a <string, []> ? I haven't found an example that DOESN'T use the <string, string> pair.

Is there another work-around for HttpClient for arrays of json data?

Answer 1

Construct the model and then serialize the entire thing before posting

var model = new{
    access_token = Settings.AuthToken,
    coordinates = locations
};
var json = JsonConvert.SerializeObject(model);
var location_content = new StringContent(json, Encoding.UTF8, "application/json");

var response = await client.PostAsync(users_url + bulk_locations_url, location_content);