Creating a JSON Request using VB.NET

I have to create a JSON request in the following format

{
"companyId": 1111,
"shipDate": "2016-08-25",
"notes": "ABC",
"Items":
[
{
"productId": 111,
"Type": "9",
"Qty": 2,
"cost": 3,
"price": 3.50,
}
]
}

So far, I have created two classes:

Public Class SaleOrder
Public Property companyId As Integer
Public Property shipDate As Date
Public Property notes As String
Public Property Items As Items
End Class

Public Class Items
Public Property productId As Integer
Public Property Type As String
Public Property Qty As Integer
Public Property cost As Double
Public Property price As Double
End Class

Below is my code in VB.NET

Dim OrderList As New List(Of SaleOrder()
Dim SaleOrder As New SaleOrder()

SaleOrder.companyId= "1111"
SaleOrder.notes = "ABC"
SaleOrder.shipDate = Now.ToString("yyyy-MM-dd")

SaleOrder.Items.productId = 111
SaleOrder.Items.Type = "9"
SaleOrder.Items.Qty = 3
SaleOrder.Items.cost = 2
SaleOrder.Items.price = 3.5

OrderList.Add(SaleOrder)

I am getting "object reference not set to instance..." error on
SaleOrder.Items.productId

It the way I am trying to create the Items array wrong?

Angel02Asked: 2016-08-25

Who is Participating?

LVL 71

Éric MoreauSenior .Net ConsultantCommented: 2016-08-26

if you would like to be clean, your class:

Public Class Items

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should be declared as:

Public Class Item

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because a class instance contains only 1 item

you will have to change your property for:

Public Property Items As new list(of Item)

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then you do something like to create an instance of the class:

dim x as new Item
x.productId = 111
x.Type = "9"
x.Qty = 3
x.cost = 2
x.price = 3.5

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to finally add your item to the collection:

SaleOrder.Items.Add(x)

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LVL 4

rotem156Commented: 2016-08-25

You're welcome.

LVL 71

Éric MoreauSenior .Net ConsultantCommented: 2016-08-25

change;

Public Property Items As Items

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for

Public Property Items As new list(of Items)

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Angel02Author Commented: 2016-08-25

Thanks! Got it. I made the following change

Dim Item As New Items()

Item.productId = 111
Item.Type = "9"
Item.Qty = 3
Item.cost = 2
Item.price = 3.5

SaleOrder.Item = Item
OrderList.Add(SaleOrder)

This created the JSON request as

[{
"companyId": 1111,
"shipDate": "2016-08-25",
"notes": "ABC",
"Items":
{
"productId": 111,
"Type": "9",
"Qty": 2,
"cost": 3,
"price": 3.50,
}
}]

Items is created as an object. How to I convert it to array so it looks exactly like the sample in my question?

LVL 71

Éric MoreauSenior .Net ConsultantCommented: 2016-08-25

have you tried :

Public Property Items As new list(of Items)

Open in new window

Angel02Author Commented: 2016-08-26

If I declare Items as

Public Property Items As new list(of Items)

Can you please let me know how do I assign it values?

Item.productId = 111
Item.Type = "9"
Item.Qty = 3
Item.cost = 2
Item.price = 3.5

as the above wouldn't work anymore.