Question

So I’m working on an MVC 3 project that pulls from multiple (10) tables from a legacy data source to a Master View with 6 partials. There is one table that has data on every child view, so we decided to store that in session data and then populate the rest of the child views with whatever other data is needed.

When we originally tried to do this, we were getting null reference exceptions to the session data. I’ve come up with a solution, but it seems very clunky and I don’t think it’s best practices/introducing unnecessary state.

Relevant code to follow:

This is what we have on the main controller:

public ActionResult PolicyView(string PolicyID)
    {
        IPolicyHolder phdata = new PolicyHolderData();
        Polmast policy = phdata.GetPolicyFromUV(PolicyID);
        ViewBag.FullName = policy.FULLNAME;
        ViewBag.PolicyID = PolicyID;
        Session["polmast"] = policy;
        return View("PolicyView");
    }

And then in our main view, one of the links to the partial child views:

<div id="Billing">
@{ Html.RenderAction("Billing", Session["polmast"] ); }
</div>

In the child controller:

public ActionResult Billing(object sessiondata)
    {
        return PartialView("_Billing", sessiondata);
    }

And in the child view:

@{var polmast = (Polmast)Session["polmast"];}
**snip**

<table id="premiumsgrid" class="display" border="1" 
cellpadding="0" cellspacing="0" width="50%">
<thead>
    <tr>
        <th>Annual</th>
        <th>Semi-Annual</th>
        <th>Quarterly</th>
        <th>Monthly</th>
    </tr>
</thead>
<tbody>
    <tr>
        <td>@polmast.PAN</td>
        <td>@polmast.PSA</td>
        <td>@polmast.PQT</td>
        <td>@polmast.PMO</td>
    </tr>

</tbody>
</table>

Answer 1

I would recommend starting to use models and returning those to your views instead of passing around the session object and casting it within your view. It would make this code much more clean.

This is how I would structure my code:

public ActionResult PolicyView(string PolicyID)
    {
        IPolicyHolder phdata = new PolicyHolderData();
        Polmast policy = phdata.GetPolicyFromUV(PolicyID);

        PolicyModel model = new PoliceModel() {
            FullName = policy.FULLNAME,
            PolicyID = PolicyID
            //Populate other properties here.
        };

        Session["polmast"] = policy;

        return View("PolicyView", model);
    }

Then I would set up your main view (there’s no need to wrap this call in curly braces and you shouldn’t need to pass any route values):

<div id="Billing">
    @Html.RenderAction("Billing")
</div>

The child controller:

public ActionResult Billing()
    {
        //Get the data out of session; it should already exist since your parent controller took care of it.
        var policyData = (Polmast)Session["polmast"];

        PolicyModel model = new PoliceModel() {
            FullName = policy.FULLNAME,
            PolicyID = PolicyID
            //Populate other properties here.
        };

        return PartialView("_Billing", model);
    }

And your child view:

@model Polmast
snip

<table id="premiumsgrid" class="display" border="1" 
cellpadding="0" cellspacing="0" width="50%">
<thead>
    <tr>
        <th>Annual</th>
        <th>Semi-Annual</th>
        <th>Quarterly</th>
        <th>Monthly</th>
    </tr>
</thead>
<tbody>
    <tr>
        <td>@Model.PAN</td>
        <td>@Model.PSA</td>
        <td>@Model.PQT</td>
        <td>@Model.PMO</td>
    </tr>

</tbody>
</table>