Pass (Send) multiple parameters to ASP.Net Web API Controller using VB.Net

Hi makumbi,

You can wrap multiple parameters in a single class and use that class as a parameter to your Web API controller method.

Refer below code.

Database

For this example I have used of Northwind database that you can download using the link given below.

Download Northwind Database

Namespaces

Imports System.Collections.Generic
Imports System.Configuration
Imports System.Data.SqlClient
Imports System.Web.Http

Model

Public Class CustomerModel
    Public Property Name As String
    Public Property City As String
End Class

ApiController

Public Class CustomerAPIController
    Inherits ApiController

    <Route("api/CustomerAPI/GetCustomers")>
    <HttpPost>
    Public Function GetCustomers(ByVal customer As CustomerModel) As List(Of Customer)
        Dim customers As List(Of Customer) = New List(Of Customer)()
        Dim constr As String = ConfigurationManager.ConnectionStrings("conString").ConnectionString
        Using con As SqlConnection = New SqlConnection(constr)
            Dim query As String = "SELECT CustomerID,ContactName,City FROM Customers WHERE (ContactName LIKE @Name + '%' OR @Name IS NULL) AND (City = @City OR @City IS NULL)"
            Using cmd As SqlCommand = New SqlCommand(query)
                cmd.Connection = con
                cmd.Parameters.AddWithValue("@Name", If(Not String.IsNullOrEmpty(customer.Name), customer.Name, CObj(DBNull.Value)))
                cmd.Parameters.AddWithValue("@City", If(Not String.IsNullOrEmpty(customer.City), customer.City, CObj(DBNull.Value)))
                con.Open()
                Using sdr As SqlDataReader = cmd.ExecuteReader()
                    While sdr.Read()
                        customers.Add(New Customer With {
                            .CustomerID = sdr("CustomerID").ToString(),
                            .ContactName = sdr("ContactName").ToString(),
                            .City = sdr("City").ToString()
                        })
                    End While
                End Using

                con.Close()
            End Using
        End Using

        Return customers
    End Function

    Public Class Customer
        Public Property CustomerID As String
        Public Property ContactName As String
        Public Property City As String
    End Class
End Class

HTML

Name:<asp:TextBox ID="txtName" runat="server"></asp:TextBox>
<br />
City:<asp:TextBox ID="txtCity" runat="server"></asp:TextBox>
<asp:Button ID="btnSearch" runat="server" Text="Search" OnClick="Search" />
<hr />
<asp:GridView ID="gvCustomers" runat="server" AutoGenerateColumns="false">
    <Columns>
        <asp:BoundField ItemStyle-Width="150px" DataField="CustomerID" HeaderText="CustomerID" />
        <asp:BoundField ItemStyle-Width="150px" DataField="ContactName" HeaderText="Contact Name" />
        <asp:BoundField ItemStyle-Width="150px" DataField="City" HeaderText="City" />
    </Columns>
</asp:GridView>

Namespaces

Imports System.Net
Imports System.Text
Imports System.Web.Script.Serialization

Code

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
        If Not Me.IsPostBack Then
            Me.PopulateGridView()
        End If
    End Sub

    Protected Sub Search(ByVal sender As Object, ByVal e As EventArgs)
        Me.PopulateGridView()
    End Sub

    Private Sub PopulateGridView()
        Dim apiUrl As String = "http://localhost:26404/api/CustomerAPI"
        Dim input As Object = New With {Key
            .Name = txtName.Text.Trim(), Key
            .City = txtCity.Text.Trim()
        }
        Dim inputJson As String = (New JavaScriptSerializer()).Serialize(input)
        Dim client As WebClient = New WebClient()
        client.Headers("Content-type") = "application/json"
        client.Encoding = Encoding.UTF8
        Dim json As String = client.UploadString(apiUrl & "/GetCustomers", inputJson)
        gvCustomers.DataSource = (New JavaScriptSerializer()).Deserialize(Of List(Of Customer))(json)
        gvCustomers.DataBind()
    End Sub

    Public Class Customer
        Public Property CustomerID As String
        Public Property ContactName As String
        Public Property City As String
    End Class

Screenshot