Click here to Skip to main content
Click here to Skip to main content
Add your own
alternative version

LINQ and Dynamic Predicate Construction at Runtime

, 13 Aug 2008
Illustrating a multi-predicate injection pattern now possible with the new features of C# 3.0.
LINQDynamicPredicate_demo.zip
LINQDynamicSearchDemo
App_Data
Global.asax
NorthwindDB.dbml
NorthwindDB.dbml.layout
Properties
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="LINQDynamicSearchDemo._Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    
        <h1>Employee Impromptu Search Tool</h1>
        <p>Check the boxes to use each filter. Each text field supports partial matches, and the Birth Date is to be an inclusive date range.</p>
        <table>
            <tr>
                <td><asp:CheckBox ID="cbxUseEmployeeID" runat="server" Checked="false" 
                        Text="Use ID" /></td>
                <td><asp:TextBox ID="filterEmployeeId" runat="server"/></td>
                <td>&nbsp;</td>
                <td><asp:CheckBox ID="cbxUseLastName" runat="server" Checked="false" 
                        Text="Use Last Name" /></td>
                <td><asp:TextBox ID="filterLastName" runat="server" /></td>
                <td>&nbsp;</td>
            </tr>
            <tr>
                <td><asp:CheckBox ID="cbxUseFirstName" runat="server" Checked="false" 
                        Text="Use First Name" /></td>
                <td><asp:TextBox ID="filterFirstName" runat="server" /></td>
                <td>&nbsp;</td>
                <td><asp:CheckBox ID="cbxUseTitle" runat="server" Checked="false" 
                        Text="Use Title" /></td>
                <td><asp:TextBox ID="filterTitle" runat="server" /></td>
                <td>&nbsp;</td>
            </tr>
            <tr>
                <td><asp:CheckBox ID="cbxUseBirthDate" runat="server" Checked="false" 
                        Text="Birth Date Range" /></td>
                <td><asp:TextBox ID="filterBirthDateStart" runat="server" /></td>
                <td><asp:TextBox ID="filterBirthDateEnd" runat="server" /></td>
                <td><asp:CheckBox ID="cbxUseAddress" runat="server" Checked="false" 
                        Text="Use Address" /></td>
                <td><asp:TextBox ID="filterAddress" runat="server" /></td>
                <td>&nbsp;</td>
            </tr>
            <tr>
                <td><asp:CheckBox ID="cbxUseCity" runat="server" Checked="false" Text="Use City" /></td>
                <td><asp:TextBox ID="filterCity" runat="server" /></td>
                <td>&nbsp;</td>
                <td><asp:CheckBox ID="cbxUseState" runat="server" Checked="false" 
                        Text="Use State" /></td>
                <td><asp:DropDownList ID="filterState" DataSourceID="StateSource" DataTextField="Region" DataValueField="Region" runat="server" /></td>
                <td>&nbsp;</td>
            </tr>
            <tr>
                <td><asp:CheckBox ID="cbxUsePostalCode" runat="server" Checked="false" 
                        Text="Use Post Code" /></td>
                <td><asp:TextBox ID="filterPostalCode" runat="server" /></td>
                <td>&nbsp;</td>
                <td><asp:CheckBox ID="cbxUseCountry" runat="server" Checked="false" 
                        Text="Use Country" /></td>
                <td><asp:DropDownList ID="filterCountry" runat="server" DataSourceID="CountrySource" DataTextField="Country" DataValueField="Country" /></td>
                <td>&nbsp;</td>
            </tr>
            <tr>
                <td><asp:CheckBox ID="cbxUseHomePhone" runat="server" Checked="false" 
                        Text="Use Phone" /></td>
                <td><asp:TextBox ID="filterHomePhone" runat="server" /></td>
                <td>&nbsp;</td>
                <td><asp:CheckBox ID="cbxUseNotes" runat="server" Checked="false" 
                        Text="Use Notes" /></td>
                <td><asp:TextBox ID="filterNotes" runat="server" /></td>
                <td>&nbsp;</td>
            </tr>
            <tr>
                <td><asp:Button ID="searchButton" runat="server" Text="Search" 
                        onclick="searchButton_Click" /></td>
                <td colspan="5" />
            </tr>
        </table>
        
        <asp:GridView ID="ResultGrid" runat="server" AutoGenerateColumns="False" 
            AllowPaging="True" BackColor="White" BorderColor="#999999" BorderStyle="None" 
            BorderWidth="1px" CellPadding="3" GridLines="Vertical" 
            onpageindexchanging="ResultGrid_PageIndexChanging">
            <RowStyle BackColor="#EEEEEE" ForeColor="Black" />
            <Columns>
                <asp:BoundField DataField="EmployeeID" HeaderText="ID" 
                    SortExpression="EmployeeID" />
                <asp:BoundField DataField="LastName" HeaderText="Last Name" 
                    SortExpression="LastName" />
                <asp:BoundField DataField="FirstName" HeaderText="First Name" 
                    SortExpression="FirstName" />
                <asp:BoundField DataField="Title" HeaderText="Title" SortExpression="Title" />
                <asp:BoundField DataField="TitleOfCourtesy" HeaderText="TitleOfCourtesy" 
                    SortExpression="TitleOfCourtesy" visible="false"/>
                <asp:BoundField DataField="BirthDate" HeaderText="DOB" 
                    SortExpression="BirthDate" DataFormatString="{0:d}" />
                <asp:BoundField DataField="HireDate" HeaderText="Hired" 
                    SortExpression="HireDate" visible="false"/>
                <asp:BoundField DataField="Address" HeaderText="Address" 
                    SortExpression="Address" />
                <asp:BoundField DataField="City" HeaderText="City" SortExpression="City" />
                <asp:BoundField DataField="Region" HeaderText="State" 
                    SortExpression="Region" />
                <asp:BoundField DataField="PostalCode" HeaderText="Postal Code" 
                    SortExpression="PostalCode" />
                <asp:BoundField DataField="Country" HeaderText="Country" 
                    SortExpression="Country" />
                <asp:BoundField DataField="HomePhone" HeaderText="Phone" 
                    SortExpression="HomePhone" />
                <asp:BoundField DataField="Extension" HeaderText="Extension" 
                    SortExpression="Extension" Visible="false" />
                <asp:BoundField DataField="Notes" HeaderText="Notes" SortExpression="Notes" />
                <asp:BoundField DataField="ReportsTo" HeaderText="Boss" 
                    SortExpression="ReportsTo" Visible="false" />
                <asp:BoundField DataField="PhotoPath" HeaderText="Photo Url" 
                    SortExpression="PhotoPath" Visible="false" />
            </Columns>
            <FooterStyle BackColor="#CCCCCC" ForeColor="Black" />
            <PagerStyle BackColor="#999999" ForeColor="Black" HorizontalAlign="Center" />
            <SelectedRowStyle BackColor="#008A8C" Font-Bold="True" ForeColor="White" />
            <HeaderStyle BackColor="#000084" Font-Bold="True" ForeColor="White" />
            <AlternatingRowStyle BackColor="#DCDCDC" />
        </asp:GridView>
        
    </div>
    <asp:SqlDataSource ID="CountrySource" runat="server" 
        ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString %>" 
        SelectCommand="SELECT DISTINCT [Country] FROM [Employees]">
    </asp:SqlDataSource>
    <asp:SqlDataSource ID="StateSource" runat="server" 
        ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString %>" 
        SelectCommand="SELECT DISTINCT [Region] FROM [Employees]"></asp:SqlDataSource>
    </form>
</body>
</html>

By viewing downloads associated with this article you agree to the Terms of Service and the article's licence.

If a file you wish to view isn't highlighted, and is a text file (not binary), please let us know and we'll add colourisation support for it.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Share

About the Author

dave.dolan

United States United States
Dave works all day, and stays up all night coding and reading, surfing the intertubes.

| Advertise | Privacy | Mobile
Web03 | 2.8.140821.2 | Last Updated 14 Aug 2008
Article Copyright 2008 by dave.dolan
Everything else Copyright © CodeProject, 1999-2014
Terms of Service
Layout: fixed | fluid