Question

I’m learning ASP.Net web pages programming using Webmatrix (with razor syntax).

Goal is to have dropdown list boxes populated by values stored in a table and the selected value coming from another joined table.

The selected value should be shown before and after a post.

I also want that if there is no UserTypeId in the UserProfiles table (UserTypeId == NULL), a default “Please select” would be shown.

Table 1: UserTypes with UserTypeId and Name fields
Table 2: UserProfiles with UsertypeId as foreign key

I have the following error message and don’t find how to solve that issue: Operator ‘==’ cannot be applied to operands of type ‘int’ and ‘WebMatrix.Data.DynamicRecord’

CODE section:

var db = Database.Open("MyDatabase");

To get the UserTypeId stored in the UserProfiles table for the connected user

var selectedUserTypeId = db.QuerySingle("SELECT UserTypeId FROM UserProfiles INNER JOIN Users ON UserName=@0",authenticatedUser);

To get the list of the UserTypes

var sqlUserTypeData = "SELECT userTypeId, Name FROM UserTypes";
var userTypeData = db.Query(sqlUserTypeData);

var userTypeDataList = userTypeData.Select(userTypeDataListItem => new SelectListItem {
    Value = userTypeDataListItem.UserTypeId.ToString(),
    Text = userTypeDataListItem.Name,
    Selected = userTypeDataListItem.UserTypeId == selectedUserTypeId ? true : false
});

Last line is where the issue occurs: userTypeDataListItem.UserTypeId == selectedUserTypeId. These types cannot apparently be compared.

if(!IsPost){
    var sqlUserData = @"SELECT *,  UserTypes.Name AS UserType
                        FROM UserProfiles
                        INNER JOIN Users ON Users.UserId = UserProfiles.UserId 
                        INNER JOIN UserTypes ON UserTypes.UserTypeId = UserProfiles.UserTypeId 
                        WHERE Users.UserName=@0";

    var userData = db.QuerySingle(sqlUserData,authenticatedUser);

    userType = userData.UserType;
    }

if(IsPost){
    Validation.RequireField("userTypeCombo", "Please select");

    userId = Request.Form["userId"];
    userTypeId = Request.Form["userTypeCombo"];

if(Validation.IsValid()) {
        var updateCommand = @"UPDATE UserProfiles
                            SET UserTypeId=@0
                            WHERE UserId=@1";
        db.Execute(updateCommand, userTypeId, userId);
        Response.Redirect("~/authcontent/user");
    }

HTML section:

@if (isAuthenticated) {
    <form action="" method="post">
        @Html.ValidationSummary()
        <section class="infoblock">
            <fieldset>
                <legend>Mon profil</legend>
                <ul>
                    <li><label for="userType">Profil</label>
                        @Html.DropDownList("userTypeCombo", "Please select", userTypeDataList)</li>
                </ul>
            </fieldset>
        </section>
    </form>        
}

Answer 1

You should resolve the problem highlighted by this error message replacing

var selectedUserTypeId = db.QuerySingle(...)

with

var selectedUserTypeId = db.QueryValue(...)

or specifying the record field:

Selected = userTypeDataListItem.UserTypeId == selectedUserTypeId.UserTypeId ? true : false