Download Files From Web Server - vb.net

Question

I have the following response from a URL. How do I code to download the two files to my hard drive with the name = id.
HTTP/1.1 200 OK
Content-Type: application/json
{
"files": [
{
"format": "fillz-order-tab",
"checksum": "6b86b273ff34fce19d6b804eff5a3f5747ada4eaa22f1d49c01e52ddb7875b4b",
"acknowledged": false,
"uri": "https://file-api.fillz.com/v1/orders/created/20140611T003336Z-8b975127",
"date_created": "20140611T003336Z",
"id": "20140611T003336Z-8b975127"
},
{
"format": "fillz-order-tab",
"checksum": "d4735e3a265e16eee03f59718b9b5d03019c07d8b6c51f90da3a666eec13ab35",
"acknowledged": false,
"uri": "https://file-api.fillz.com/v1/orders/created/20140611T013545Z-3e2f2083",
"date_created": "20140611T013545Z",
"id": "20140611T013545Z-3e2f2083"
}
]
}
My code that calls the URL is the following:
Using response As HttpWebResponse = TryCast(request.GetResponse(), HttpWebResponse)
Dim reader As New StreamReader(response.GetResponseStream())
result = reader.ReadToEnd()
I am using json.net with visual basic 2008.
These are my classes
Public Class file
Public format As String
Public checksum As String
Public acknowledged As String
Public uri As String
Public date_created As String
Public id As String
End Class
Public Class RootObject
Public Property files() As List(Of file)
Get
End Get
Set(ByVal value As List(Of file))
End Set
End Property
End Class
This is my code to deserializare json results
Dim res As RootObject = JsonConvert.DeserializeObject(Of FillzAPI.FileAPI.RootObject)(result)
I want to read each id from the url response
For Each Data As FileAPI.RootObject In res
Next
I have the next error:
Expression is of type 'FillzAPI.FileAPI.RootObject', which is not a collection type.
How do I fix this error?

Answer 1

A few points which will give you working code:
There is an easier way to download the JSON data.
You've accidentally
declared RootObject.files as an array of lists, and its Get and
Set methods are empty.
File is an unfortunate name for a class as
it conflicts with System.IO.File.
It would be better to have the
things in (what I named) FileData as properties. You can take
advantage of auto-declared properties and not have to type the
Get/Set methods.
Putting all those together, I arrived at
Option Infer On
Imports System.IO
Imports System.Net
Imports Newtonsoft.Json
Module Module1
Public Class FileData
Public Property format As String
Public Property checksum As String
Public Property acknowledged As String
Public Property uri As String
Public Property date_created As String
Public Property id As String
End Class
Public Class RootObject
Public Property Files As List(Of FileData)
End Class
Sub Main()
' I set this up on a local web server. Adjust as required.
Dim src = "http://127.0.0.1/JsonSample.txt"
' An easy way to get a string from a web server...
Dim wc As New WebClient
'TODO: Try..Catch any error that wc.DownloadString throws.
Dim jsonData = wc.DownloadString(src)
'TODO: Try..Catch any error that JsonConvert.DeserializeObject throws.
Dim y = JsonConvert.DeserializeObject(Of RootObject)(jsonData)
' Somewhere to save the downloaded files...
Dim dest = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory), "My JSON test")
If Not Directory.Exists(dest) Then
Directory.CreateDirectory(dest)
End If
For Each x In y.Files
Console.WriteLine(x.uri)
'TODO: Try..Catch any error that wc.DownloadFile throws. Also perhaps use async methods.
wc.DownloadFile(x.uri, Path.Combine(dest, x.id))
Next
Console.ReadLine()
End Sub
End Module
Which outputs
https://file-api.fillz.com/v1/orders/created/20140611T003336Z-8b975127
https://file-api.fillz.com/v1/orders/created/20140611T013545Z-3e2f2083
and saves the files.