Index was out of range in Blazor

Question

When searched for Location that doesn't exist timeZoneAtLocation[0] is [] and is throwing the below error .

Please suggest on how to check nulls.

Note : Replace

"My Bing Key"

with Bing Key.

timez = data3.resourceSets[0].resources[0].timeZoneAtLocation[0].timeZone[0].convertedTime.localTime;

System.ArgumentOutOfRangeException

HResult=0x80131502

Message=Index was out of range. Must be non-negative and less than the size of the collection. (Parameter 'index')

Source=System.Private.CoreLib

StackTrace:

at System.ThrowHelper.ThrowArgumentOutOfRange_IndexMustBeLessException()

at System.Collections.Generic.List`1.get_Item(Int32 index)

at Newtonsoft.Json.Linq.JContainer.GetItem(Int32 index)

at System.Dynamic.UpdateDelegates.UpdateAndExecute2[T0,T1,TRet]

at ElevationFinder.Pages.Index.

Answer 1

I added another line and I able to trap exception

placename =data3.resourceSets[0].resources[0].timeZoneAtLocation[0].placename;

 
@page "/"
@using Newtonsoft.Json;
@using Microsoft.AspNetCore.Components.Forms
@using System.Text;
@using System.Net.Http.Headers;
<h1>Elevation </h1>
<EditForm Model="@submitActivity" OnSubmit="@Submit">
<div class="row">
    <div class="col-md-3">
        <p>Location</p>
    </div>
    <div class="col-md-4">
        <input placeholder="Location" @bind="@loc" />
    </div>
</div>
<br />
<div>
    <button type="submit">Submit</button>
</div>
<div>
    @errmsg
</div>
<br />
    @placename
<br />
    <p>Altitude</p>
 <br/>
    @elevation
    <p>Meters</p>
    <br/>
    <p>Time</p>
    <br />
    @timez
    <br />
    @timezone
    <p>Weather</p>
    <br/>
    @temparature 
    <p>C</p>
    <br />
    @tempformat
    <p>F</p>
    @weather
</EditForm>
@code {
    private string loc; string errmsg = ""; double latitude = 0.0; double tempf; double tempformat; double temparature;
    double longitude = 0.0; double elevation = 0.0; string placename;
    string time1 = "";
    string time2 = "";
    string time3 = "";
    dynamic timezone = ""; dynamic timez = ""; string weather = "";
    string timef = "";
    private ACTIVITY submitActivity { get; set; } = new();
    public class ACTIVITY
    {        public string Dummy { get; set; }
    }
    private  async Task Submit()
    {
        string key = "MY Bing Key";
        string query = loc; 
        using (HttpClient client = new HttpClient())
        {
            string timez = "";
            string final = "";
            string timezone = "";
            string checknull = "";
            string time3 = "";
            string timef = ""; 
            Uri geocodeRequest = new Uri(string.Format("https://dev.virtualearth.net/REST/v1/Locations?q={0}&key={1}", query, key));
            client.BaseAddress = new Uri(geocodeRequest.ToString());
            client.DefaultRequestHeaders.Clear();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
            HttpResponseMessage response1 = null;
            try
            {
                response1 = await client.GetAsync(geocodeRequest);
                string     jsonstring = await response1.Content.ReadAsStringAsync();
                // Parse the JSON response to extract the address
                dynamic data1 = Newtonsoft.Json.JsonConvert.DeserializeObject(jsonstring);
                var result1 = data1.resourceSets[0].resources[0];
                latitude = result1.point.coordinates[0];
                longitude = result1.point.coordinates[1];
            }
            catch (Exception e)
            {
                loc = "";
                timez = "";
                errmsg = "Invalid Location";
            }
        }
        using (HttpClient client1 = new HttpClient())
        {
            Uri elevationReq = new Uri($"https://api.open-meteo.com/v1/elevation?latitude={latitude}&longitude={longitude}");
            client1.BaseAddress = new Uri(elevationReq.ToString());
            client1.DefaultRequestHeaders.Clear();
            client1.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
            HttpResponseMessage response2 = null;
            try
            {
                response2 = await client1.GetAsync(elevationReq);
                string jsonstring2 = await response2.Content.ReadAsStringAsync();
                // Parse the JSON response to extract the address
                dynamic datael = Newtonsoft.Json.JsonConvert.DeserializeObject(jsonstring2);
                elevation = datael.elevation[0];
            }
            catch (Exception e)
            {
                loc = "";
                elevation = 0;
                errmsg = "Invalid Location";
            }
        }
        using (HttpClient client3 = new HttpClient())
        {
            string urlw = $"https://api.open-meteo.com/v1/forecast?latitude={latitude}&longitude={longitude}&current_weather=true";
            client3.BaseAddress = new Uri(urlw.ToString());
            client3.DefaultRequestHeaders.Clear();
            client3.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
            HttpResponseMessage responsew = null;
            try
            {
                responsew = await client3.GetAsync(urlw);
                string jsonw = await responsew.Content.ReadAsStringAsync();
                dynamic dataw = Newtonsoft.Json.JsonConvert.DeserializeObject(jsonw);
                tempf = (dataw.current_weather.temperature * 1.8) + 32;
                tempformat = Math.Round(tempf, 1);
                temparature = dataw.current_weather.temperature;
                int weathercode = dataw.current_weather.weathercode;
                switch (weathercode)
                {
                    case 0:
                        weather = "Clear Sky";
                        break;
                    case 1:
                        weather = "Mainly Clear";
                        break;
                    case 2:
                        weather = " partly cloudy";
                        break;
                    case 3:
                        weather = "overcast";
                        break;
                    case 51:
                        weather = "Rain  Slight";
                        break;
                    case 53:
                        weather = "Rain moderate";
                        break;
                    case 55:
                        weather = "Rain heaving intensity";
                        break;
                    case 71:
                        weather = "Snowfall  Slight";
                        break;
                    case 73:
                        weather = "Snowfall moderate";
                        break;
                    case 75:
                        weather = "Snowfall heaving intensity";
                        break;
                    case 80:
                        weather = "Rain showers slight";
                        break;
                    case 81:
                        weather = "Rain showers moderate";
                        break;
                    case 82:
                        weather = " Rain showers violent";
                        break;
                    case 85:
                        weather = "Snow showers slight";
                        break;
                    case 86:
                        weather = " Snow showers heavy";
                        break;
                    case 95:
                        weather = " Thunderstorm: Slight or moderate";
                        break;
                    default:
                        weather = " ";
                        break;
                }
            }
            catch (Exception e)
            {
                loc = "";
                temparature = 0.0; tempformat = 0.0;
                errmsg = "Invalid Location";
            }
        }
        using (HttpClient client2 = new HttpClient())
        {
            Uri geocodetime = new Uri(string.Format("https://dev.virtualearth.net/REST/v1/timezone/?q={0}&key={1}", query, key));
            client2.BaseAddress = new Uri(geocodetime.ToString());
            client2.DefaultRequestHeaders.Clear();
            client2.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
            HttpResponseMessage response3 = null;
            string final = "";
            int len;
            string checknull = "";
            string checkflag = "N";
            response3 = await client2.GetAsync(geocodetime);
            string jsonstring3 = await response3.Content.ReadAsStringAsync();
            // Parse the JSON response to extract the address
            dynamic data3 = Newtonsoft.Json.JsonConvert.DeserializeObject(jsonstring3);
            try
            {
                placename =data3.resourceSets[0].resources[0].timeZoneAtLocation[0].placeName;
                timez = data3.resourceSets[0].resources[0].timeZoneAtLocation[0].timeZone[0].convertedTime.localTime;
                timezone = data3.resourceSets[0].resources[0].timeZoneAtLocation[0].timeZone[0].convertedTime.timeZoneDisplayName;
            }
            catch (Exception e)
            {
                loc = "";
                timez = "";
                timezone = "";
                errmsg = "Invalid Location";
                weather = "";
                elevation = 0.0;
                placename = ""; tempformat = 0.0; temparature = 0.0;
            }
             
            
        }
          }
}

Answer 2

Check the length of the timeZoneAtLocation property before trying to use it.

if (data3.resourceSets[0].resources[0].timeZoneAtLocation.Length > 0) 
{
	placename =data3.resourceSets[0].resources[0].timeZoneAtLocation[0].placeName;
	timez = data3.resourceSets[0].resources[0].timeZoneAtLocation[0].timeZone[0].convertedTime.localTime;
	timezone = data3.resourceSets[0].resources[0].timeZoneAtLocation[0].timeZone[0].convertedTime.timeZoneDisplayName;       
} 
else 
{
	loc = "";
	timez = "";
	timezone = "";
	errmsg = "Invalid Location";
	weather = "";
	elevation = 0.0;
	placename = ""; tempformat = 0.0; temparature = 0.0;
}