Xamarin : How to submit form data using API POST method

Xamarin : How to submit form data using API POST method

Design

<StackLayout Orientation="Vertical">
 
  <Grid>
    <Grid.RowDefinitions>
      <RowDefinition Height="30"></RowDefinition>
      <RowDefinition Height="30"></RowDefinition>
      <RowDefinition Height="30"></RowDefinition>
      <RowDefinition Height="30"></RowDefinition>
      <RowDefinition Height="30"></RowDefinition>
      <RowDefinition Height="30"></RowDefinition>
      <RowDefinition Height="30"></RowDefinition>
      <RowDefinition Height="30"></RowDefinition>
      <RowDefinition Height="30"></RowDefinition>
      <RowDefinition Height="30"></RowDefinition>
      <RowDefinition Height="30"></RowDefinition>
      <RowDefinition Height="30"></RowDefinition>
      <RowDefinition Height="30"></RowDefinition>
      <RowDefinition Height="*"></RowDefinition>
    </Grid.RowDefinitions>
 
    <Grid.ColumnDefinitions>
      <ColumnDefinition Width="*"></ColumnDefinition>
    </Grid.ColumnDefinitions>
 
    <Label Grid.Row="0" Grid.Column="0"  Text="Username:"></Label>
    <Entry Grid.Row="1" Grid.Column="0"  x:Name="txtUsername"></Entry>
                                         
    <Label Grid.Row="2" Grid.Column="0"  Text="Password:"></Label>
    <Entry Grid.Row="3" Grid.Column="0"  x:Name="txtPassword"></Entry>
                                         
    <Label Grid.Row="4" Grid.Column="0"  Text="First Name:"></Label>
    <Entry Grid.Row="5" Grid.Column="0"  x:Name="txtFirstName"></Entry>
                                         
    <Label Grid.Row="6" Grid.Column="0"  Text="Last Name:"></Label>
    <Entry Grid.Row="7" Grid.Column="0"  x:Name="txtLastName"></Entry>
                                         
    <Label Grid.Row="8" Grid.Column="0"  Text="Email:"></Label>
    <Entry Grid.Row="9" Grid.Column="0"  x:Name="txtEmailId"></Entry>
                                         
    <Label Grid.Row="10" Grid.Column="0" Text="Mobile:"></Label>
    <Entry Grid.Row="11" Grid.Column="0" x:Name="txtMobile"></Entry>
 
    <Label Grid.Row="12" Grid.Column="0" x:Name="OutputName" FontSize="15" 

                  HorizontalTextAlignment="Center" ></Label>
 
    <Button Grid.Row="13" Grid.Column="0" Text="Submit" Clicked="OnSubmit" ></Button>
    
  </Grid>
  </StackLayout>

Code

async void OnSubmit(object sender, EventArgs e)
       {
           if (!string.IsNullOrEmpty(txtUsername.Text) 

                  && !string.IsNullOrEmpty(txtPassword.Text) 

                  && !string.IsNullOrEmpty(txtFirstName.Text) 

                  && !string.IsNullOrEmpty(txtLastName.Text) 

                  && !string.IsNullOrEmpty(txtEmailId.Text) 

                  && !string.IsNullOrEmpty(txtMobile.Text))
           {
               try
               {
                   HttpClient client = new HttpClient();
 
                   string requestPayload = "{\"UserName\": \""+txtUsername.Text+"\"" + "," +
                           "\"Password\": \"" +txtPassword.Text+"\"" +","+ 
                           "\"FirstName\":\""+txtFirstName.Text+ "\"" + "," +
                           "\"LastName\": \"" +txtLastName.Text+ "\"" + "," +
                           "\"EmailId\":  \"" +txtEmailId.Text+ "\"" + "," +
                           "\"Mobile\":   \"" +txtMobile.Text+ "\"" + "}"  ;
                   var response = await client.PostAsync("http://domainname/DemoAPI/API/User/AddUser", 

                                       new StringContent(requestPayload, Encoding.UTF8, "application/json"));
 
                   if (response.StatusCode == HttpStatusCode.OK)
                   {
                       OutputName.Text = "Data Saved.";
                   }
               }
               catch (Exception ex)
               {
                   OutputName.Text = ex.Message;
               }
           }
           else
           {
               OutputName.Text = "Please fill up complete form";
           }
       }

Output