In this article, I will integrate and setup ELMAH to asp.net MVC project. I will finish whole article in 5 different steps. ELMAH stands for Error Logging Modules and Handlers providing application wide error logging facilities. ELMAH is pluggable and easy to implement without changing single line of code. ELMAH work as interceptor of unhandled dotnet exceptions, that display over yellow screen of death. As per Author you can dynamically add ELMAH on running asp.net application without recompile or re-deploy whole application.You can download ELMAH binaries from google code or if you are using nuget then visit ELMAH nuget page.

Install

The best way to install any module to Asp.net MVC project is to use Nuget package Console. You can visit ELMAH nuget page for get latest version command.

Configure

After installing ELMAH , it will automatically update Web.Config file. If it's not so you can add following code to Web.Config file.

<configuration>
<configSections>
    <sectionGroup name="elmah">
      <section name="security" requirePermission="false" type="Elmah.SecuritySectionHandler, Elmah" />
      <section name="errorLog" requirePermission="false" type="Elmah.ErrorLogSectionHandler, Elmah" />
      <section name="errorMail" requirePermission="false" type="Elmah.ErrorMailSectionHandler, Elmah" />
      <section name="errorFilter" requirePermission="false" type="Elmah.ErrorFilterSectionHandler, Elmah" />
    </sectionGroup>
</configSections>

<system.web>   
    <httpModules>
      <add name="ErrorLog" type="Elmah.ErrorLogModule, Elmah" />
      <add name="ErrorMail" type="Elmah.ErrorMailModule, Elmah" />
      <add name="ErrorFilter" type="Elmah.ErrorFilterModule, Elmah" />
    </httpModules>
</system.web>

<system.webServer>
<modules>
      <add name="ErrorLog" type="Elmah.ErrorLogModule, Elmah" preCondition="managedHandler" />
      <add name="ErrorMail" type="Elmah.ErrorMailModule, Elmah" preCondition="managedHandler" />
      <add name="ErrorFilter" type="Elmah.ErrorFilterModule, Elmah" preCondition="managedHandler" />
</modules>
</system.webServer>
<elmah>
    <security allowRemoteAccess="false" />
    <errorLog type="Elmah.SqlErrorLog, Elmah" connectionStringName="YourConnectionStringName" />
</elmah>
    <location path="elmah.axd" inheritInChildApplications="false">
    <system.web>
      <httpHandlers>
        <add verb="POST,GET,HEAD" path="elmah.axd" type="Elmah.ErrorLogPageFactory, Elmah" />
      </httpHandlers>
      <!--
      <authorization>
        <allow roles="admin" />
        <deny users="*" /> 
      </authorization>
      --> 
    </system.web>
    <system.webServer>
      <handlers>
        <add name="ELMAH" verb="POST,GET,HEAD" path="elmah.axd" type="Elmah.ErrorLogPageFactory, Elmah" preCondition="integratedMode" />
      </handlers>
    </system.webServer>
  </location>
</configuration>
Usage Now, It's time to use and test elmah for application. Generate exception in Home Controller
public ActionResult Index()
{
   throw new Exception("This is test Exception");
          
   return View();
}

after generating exception check your elmah like http://www.example.com/elmah.axd
Here is our output

Security

In addition ELMAH provides seamless security feature to prevent unauthorized access. Please read our next article to make your elmah secure.

Filtering

ELMAH identify and store exceptions in different category, you can make or edit ELMAH error screen with different filters which we will discuss in our next ELMAH series.

Notification

You can setup ELMAH email notification when any exception occurs. To unable notification option you must include below code

Add ErrorMail module
<httpModules>
    <add name="ErrorMail" type="Elmah.ErrorMailModule, Elmah"/>
</httpModules>

Add SMTP Setting
<system.net>
    <mailSettings>
        <smtp deliveryMethod="network">
            <network host="..." port="25" userName="..." password="..." />
        </smtp>
    </mailSettings>
</system.net>
 
or
<elmah>
<errorMail from="..." to="..."  async="true" smtpServer="..." smtpPort="25" userName="..." password="..." />
</elmah>

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While creating a Html TextBox or Dropdown list using jQuery, it would define the ID and Name attributes of an Html TextBox or Dropdown list. First, let's us understand what is ID and Name attribute of Html controls. ID attribute of an input html control is responsible for uniquely identified a control on the html page. We use ID for getting an input html control's value using jQuery at client side or for applying some CSS to that control. And Name attribute of an input html control is responsible for posting that control values on server side.

When you will not defined the Name attributes of an Html TextBox or Dropdown list then form will not post the TextBox or Dropdown list values to the server. It means at controller's action result, you will not find the Html TextBox or Dropdown list. Then, you need to select no of customers from drop down list as shown below:

Also, Textboxes for entering customers full name are created by jQuery as shown below:

When you will submit the form you will get the Textboxes created by jQuery at controller side as shown below:

Here's the view code:

    <script src="~/Scripts/jquery-1.8.2.js"></script>
    <script>
    $(document).ready(function () {
    $("#ddl").change(function () {
    var i = $("#ddl :selected").val();
    var str = "";
    for (var j = 1; j <= i; j++) {
    var id = "txtCustomer" + j;
    //Remember to add name attribute to get values at server side
    str = str + "<span>Customer " + j + " Full Name: </span><input type='text' id='" + id + "' name='" + id + "'/><br/>";
    }
    $("#content").html(str);
    });
    });
    </script>
    
    <br />
    @using (Html.BeginForm())
    {
    <h2>Get TextBoxes Values Created by jQuery</h2>
    <span>Select No. of Customers </span>
    <select id="ddl" name="ddl">
    <option>Select</option>
    <option>1</option>
    <option>2</option>
    <option>3</option>
    <option>4</option>
    </select>
    <br />
    <div id="content">
    </div>
    <br />
    <div align="center">
    <input type="submit" id="btnSave" value="Save" />
    </div>
    }

And you can get the Html TextBox or Dropdown list values created by jQuery by two method: Get Values Using FormCollection and Get Values Using Request.Form.

Method 1: Get Values Using FormCollection

    public ActionResult Index()
    {
    return View();
    }
    
    [HttpPost]
    public ActionResult Index(FormCollection form, string ddl)
    {
    for (int i = 1; i <= Convert.ToInt32(ddl); i++)
    {
    string id = "txtCustomer" + i;
    string customer = form[id];
    }
    return View();
    }

Method 2: Get Values Using Request.Form

  public ActionResult Index()
    {
    return View();
    }
    
    [HttpPost]
    public ActionResult Index(string ddl)
    {
    for (int i = 1; i <= Convert.ToInt32(ddl); i++)
    {
    string id = "txtCustomer" + i;
    string customer = Request.Form[id];
    }
    return View();
    }

Hope you will enjoy this tutorial!

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