how to search data form XML in ASP.NET webforms-CodePudding

I'm new to ASP.NET. I am developing a search application in ASP.NET webforms and it will receive from an XMl file. When I type in the textbox like student_name or ID and click submit button it should retrieve the data of the student from the XML like their Honours in a nice format. This is the sample that I have made but it's not working.

aspx file

<body style="height: 171px">

<h1>Student Graduation</h1>

<form runat="server">
    Search for 
    <asp:TextBox ID="SearchTextBox" runat="server" />
    <asp:Button ID="SearchButton" Text="Search!" runat="server" OnClick="SearchButton_Click" />
</form>


<div id="student_output" runat="server"></div>

aspx.cs

  protected void Page_Load(object sender, EventArgs e)
  {
    XmlDocument xmlDoc = new XmlDocument();

    protected void Page_Load(object sender, EventArgs e)
    {

        xmlDoc.Load(Server.MapPath("student_list.xml"));

        XmlNodeList Students = xmlDoc.DocumentElement.GetElementsByTagName("Student");

        String htmlString = "";

        for (int i = 0; i < Students.Count; i  )
        {
            XmlNode Student = Students[i];

            htmlString  = "<h2>"   Student.SelectSingleNode("Student_Name").InnerText   "</h2>";

            htmlString  = "<p>";

            htmlString  = Student.SelectSingleNode("ID").InnerText   ", ";

            htmlString  = Student.SelectSingleNode("Honours").InnerText   ", ";

            htmlString  = Student.SelectSingleNode("Programme").InnerText   ", ";

            htmlString  = Student.SelectSingleNode("Book_Price").InnerText   ". ";

            htmlString  = "</p>";

        }
        student_output.InnerHtml = htmlString;
    }

    protected void SearchButton_Click(object sender, EventArgs e)
    {
        String searchKey = SearchTextBox.Text;

        XmlNode Student = xmlDoc.SelectSingleNode("//Student[Student_Name='"   searchKey   "']");

        if (Student != null)
        {
            string htmlString = "";

            htmlString  = "<h2>"   Student.SelectSingleNode("Student_Name").InnerText   "</h2>";

            htmlString  = "<p>";

            htmlString  = Student.SelectSingleNode("ID").InnerText   ", ";

            htmlString  = Student.SelectSingleNode("Honours").InnerText   ", ";

            htmlString  = Student.SelectSingleNode("Programme").InnerText   ". ";

            htmlString  = Student.SelectSingleNode("Book_Price").InnerText   ". ";

            htmlString  = "</p>";

            student_output.InnerHtml = htmlString;
        }
    }
}

}

XML File

<Graduate>

<Student>
    <ID> 01944422</ID>
    <Student_Name>Peter Parker</Student_Name>
    <Honours> First Class </Honours>
    <Book_Price>Yes</Book_Price>
    <Programme>Comp. Science</Programme>
</Student>

<Student>
    <ID>01923455</ID>
    <Student_Name>Bryan Adam</Student_Name>
    <Honours>Second class</Honours>
    <Book_Price>No</Book_Price>
    <Programme>Mathematics</Programme>
</Student>

<Student>
    <ID>01952345</ID>
    <Student_Name>Maggie Fong</Student_Name>
    <Honours>First class</Honours>
    <Book_Price>Yes</Book_Price>
    <Programme>Accounting</Programme>
</Student>

<Student>
    <ID>01998745</ID>
    <Student_Name>Melissa Teh</Student_Name>
    <Honours>First class</Honours>
    <Book_Price>Yes</Book_Price>
    <Programme>Finance</Programme>
</Student>


<Student>
    <ID>01899888</ID>
    <Student_Name>Ahmad bin Suhail</Student_Name>
    <Honours>Second class</Honours>
    <Book_Price>No</Book_Price>
    <Programme>Engineering</Programme>
</Student>

<Student>
    <ID>01900847</ID>
    <Student_Name>Lechumanan a/l Vicky</Student_Name>
    <Honours>Third class</Honours>
    <Book_Price>No</Book_Price>
    <Programme>Comp. Science</Programme>
</Student>

<Student>
    <ID>04503967</ID>
    <Student_Name>Soo Tong Wei</Student_Name>
    <Honours>Third class</Honours>
    <Book_Price>No</Book_Price>
    <Programme>Mathematics</Programme>
</Student>

CodePudding user response：

convert the xml to a dataset, then everything becomes a walk in the park.

So, this markup:

    <div>
        <h1>Student Graduation</h1>
            Search for 
            <asp:TextBox ID="SearchTextBox" runat="server" />
            <asp:Button ID="SearchButton" Text="Search!" runat="server" OnClick="SearchButton_Click" 
                CssClass="btn" style="margin-left:15px"       />

        <br />
        <asp:GridView ID="GridView1" runat="server" CssClass="table" Width="40%">
        </asp:GridView>
    </div>

Ok, and then this code:

   protected void SearchButton_Click(object sender, EventArgs e)
    {
        string sFile  = @"C:\Test7\sData.txt";
        DataSet MyData = new DataSet();
        MyData.ReadXml(sFile);

        // if blank, then show all data
        DataTable MyTable = MyData.Tables[0];
        if (SearchTextBox.Text != "")
        {
            string s = SearchTextBox.Text;
            // user entered somthing
            // if text, then match on stuent name

            if (s.All(char.IsNumber))
            {
                // number, lets filter by ID
                MyTable.DefaultView.RowFilter = "ID = "   s;
            }
            else
            {
                // search Student name - partial match
                MyTable.DefaultView.RowFilter = "Student_Name like '%"   s   "%'";
            }
        }

        GridView1.DataSource = MyTable;
        GridView1.DataBind();
    }

So, if we enter nothing, then we show all and see this:

And I used a wild card search for the name - we could I suppose JUST match on say the start, but you can say search for "B", and you get this:

Of course, if you enter a number, then I search by ID, and say this:

And I suppose we should add to the GV a "no data row, say like this:

        <asp:GridView ID="GridView1" runat="server" CssClass="table" Width="40%">
            <EmptyDataTemplate>
                <h2>No data found</h2>
            </EmptyDataTemplate>
        </asp:GridView>

So, now for a failed search, we would get this: