I have a small asp.net core mvc application that basically consists of a form that a user can input some constraints into, and then get a filtered list of data depending on those constraints.
The controller action for filtering data basically looks like this:
[HttpPost]
public async Task<IActionResult> Query(QueryModel query)
{
var customers = await _context.Customers.AsQueryable().FilterCustomerList(query);
return View("Index", customers);
}
Now, my issue is that I would like the inputs in the fields to persist after entering them and being redirected to the view again. Right now they are currently just reset.
One way of doing this that I found was using viewBag. An example for a single query attribute is this:
public async Task<IActionResult> Query(QueryModel query)
{
var customers = await _context.Customers.AsQueryable().FilterCustomerList(query);
ViewBag.Name = query.Name;
return View("Index", customers);
}
and then the inpuit html elelment would look like:
<div class="col-md-4">
<input name="Name" type="text" placeholder="First name" value="#ViewBag.Name"class="form-control">
</div>
And this makes sure that if something has been entered into a field, it will now be entered into the field when after the query has been submitted.
But when I read up on ViewBag, I understand that a lot of .net developers have an aversion to it. It's not safe, the compiler can't catch errors in it easily etc.
Also, If I were to add all the input fields in my form to the viewbag, I would need a lot of lines of ViewBag.Attribute = query.SomeAttribute (20-30). Which seems like a code-smell too.
Is there any nicer way to do what I am trying to here?
You haven't included your QueryModel class and that class could be a key point to a cleaner approach.
You see, usually the user data, POSTed to your action is bound to the model, from there it's rendered on the form and is POSTed again. The model binding is where an input of a specific name is bound to a model member of the same name.
Thus, there's no need for viewbags.
More formally:
The Model
public class QueryModel
{
[your-validators-in-attributes, e.g. Required or MaxLength
there can be multiple validators]
public string Name { get; set; }
}
The controller:
[HttpPost]
async Task<IActionResult> Query(QueryModel query)
{
// query.Name is there, bound from the view
}
The View:
#model .....QueryModel
<div>
#Html.TextBoxFor( m => m.Name, new { placeholder = "a placeholder" } )
</div>
The html helper does two things
renders an input of the given name (Name in this case)
sets its value depending on the actual value from the model
In newer ASP.NETs you can achieve similar result by using tag helpers, where instead of Html.TextBoxFor(...) you write
<input asp-for="Name" />
These two approaches, using html helpers or using tag helpers are equivalent. In both cases there's no need for view bags.
First post here so be gentle please :)
I am creating an ASP.NET with MVC web app that shows a list of items of the same class (Laptop)
I want to create a Dropdown list in the main view below each title that will allow me to filter the results OnChange - hence the selection is empty, but the user can click and select the value in the DropDown list, and the main view items list will update immediately according to the selection.
This is how the list looks now:
Snapshot of the list
I want to implement a dropdown, but I can't seem to get the selected value from the dropdown: (The DropDownlist is populated properly, and working)
<select class="form-control" asp-items="Html.GetEnumSelectList<purpose>()"
onchange="#{Model = Model.Where(m=>m.Purpose == /*HERE SHOULD BE THE VALUE SELECTED*/)}">
<option selected="selected" value="">-Select one-</option>
</select>
And then refreshing the page... but - how do I get the selected value from inside the selection?
If it was in JavaScript I would have done:
html.document.getElementById("The id of the selection").value
but I don't want JavaScript since this is all ASP.NET
To be clear, I have 5 different dropdown lists to filter by, and they can be selected or not.
You're mixing up client-side vs. server-side code. The example below uses only MVC and a full client-server architecture. Each request requires a round-trip to the server.
You have 3 components in this scenario.
ProductsViewModel.cs
public class ProductsViewModel
{
public IList<Laptop> Laptops { get; set; }
public PurposeEnum Purpose { get; set; }
}
ProductsController.cs
public class ProductsController : Controller
{
[HttpGet]
public IActionResult Index()
{
// Retrieve all records without a filter
var unfiltered = db.Laptops.ToList();
var viewModel = new ProductsViewModel() { AvailableLaptops = unfiltered };
return View(viewModel);
}
[HttpPost]
public IActionResult Index(ProductsViewModel viewModel)
{
// Use viewModel.Purpose & viewModel.Maker to filter records from database
var filtered = db.Laptops.Where(l => l.Purpose == viewModel.Purpose).ToList();
var filteredViewModel = new ProductsViewModel()
{
AvailableLaptops = filtered,
Purpose = viewModel.Purpose
};
return filteredViewModel;
}
}
Products\Index.cshtml
#model MyNameSpace.ViewModel
using (BeginForm())
{
#Html.DropDownList(Html.GetEnumSelectList<PurposeEnum>())
foreach (var l in Model.AvailableLaptops)
{
// Loop through Model.AvailableLaptops and generate table
}
<input type="submit" value="Search" />
}
When you visit the URL /Products/Index for the first time, the GET action handler will be triggered. It will generate an unfiltered list of your products along with the dropdown list required for filtering.
When you make your selection and submit the form, the POST action handler will be triggered, and use the selected values in the Purpose and Maker properties of the view model to filter the records. The same view is generated, but with a filtered down list of products.
This is very basic code that ignores validation, error handling and security.
I am a beginner and currently started a small project for my study purpose. A mini DB search portal. I created front end View. It has one search box and a button. Now what I need is, I have to fetch the data from DB, related to the user entered search term on clicking on the button.
How to proceed to get the user entered data from view to controller and process it for further operations.
General code:
view:
#using(Html.BeginForm("Search","Test"))
{
<input type="text" name="txtName"/>
<input type="submit" value="Generate report" />
}
Controller
[HTTPPost]
public ActionResult Seacrh(FormCollection form) // "Search" is action name specified in view for controller "TestController"
{
string text = form["txtName"]; // txtName is name of input in view.
}
However to take full advantage to MVC have a look at Model Binding in MVC
I recommend reading this article, it has an example different ways of adding search.
You can update the Index method in your Controller and View as follows:
1)Add a form to the view that will post to the view itself
View
#using (Html.BeginForm()){
<p> Title: #Html.TextBox("SearchString") <br />
<input type="submit" value="Filter" /></p>
}
2)Add a parameter to the Index method to filter the content based on the parameter passed. public ActionResult Index(string searchString)
Controller
var movies = from m in db.Movies
select m;
if (!String.IsNullOrEmpty(searchString))
{
movies = movies.Where(s => s.Title.Contains(searchString));
}
return View(movies);
There is an asp.net mvc 4 website. The users want to re-start the web application from scratch. What's the best way to clear all the login/membership information. Just use Sql server management studio to delete the records in all the tables? (webpages_*, and UserProfile)?
There is an added column in table UserProfile which refers to an user defined table.
Or maybe just drop the whole database using SSMS? Or delete all the tables (include the __MigrationHistory) in the database?
In the controller you use for handling the users, you can create an action method to delete a user. In this example it's the current user that will be deleted, including all related data.
public ActionResult DeleteMe()
{
Membership.DeleteUser(User.Identity.Name, deleteAllRelatedData: true);
FormsAuthentication.SignOut();
return RedirectToAction("Login", "Account");
}
To call the action method above just add the following code in a view to display a button...
#using (Html.BeginForm("DeleteMe","Account"))
{
#Html.AntiForgeryToken()
#Html.ValidationSummary()
<fieldset>
<input type="submit" value="Delete my account" />
</fieldset>
}
...or this, if you want to display a link.
#Html.ActionLink("Delete my account", "DeleteMe", "Account")
If you want the function to delete another user and not yourself you can modify the action method above and do something like this:
public ActionResult DeleteUser(string userName)
{
Membership.DeleteUser(userName, deleteAllRelatedData: true);
}
Note that you need to add a bit more of security to this to check that the user calling this method actually has the right to do it...but this is the basics regarding how to delete a user.
I am trying to create a timesheet application in MVC 2, but I feel like I am still struggling to grasp the model/view relationships and all that.
The problem I have is, I want to let the user report a new time segment in a create view. But I want to have dropdownlists populated with Projects, Tasks, and Consultants from the model.
Basically the database structure looks like this:
(table) TimeSegments
TimeSegmentID
Hours
Date
ConsultantID (FK)
TaskID (FK)
ProjectID (FK)
(table) Projects
ProjectID
ProjectName
(table) Tasks
TaskID
TaskName
(table) Consultants
ConsultantID
ConsultantName
This design may be extended in future, right now I want to get basic functionality working before I complicate it further.
Now, I am passing the entire model to the create view (actually a viewmodel based on it, just to simplify some coding, but it might as well have been the entire model).
The problem is, normally when I have done similar things with a create view, I would have created a new object in the controller and passed that to the view. In this case it would have been the TimeSegment object, since it is a new time segment that should be created in the database. Then I could just submit it and update the database in the controller. However, if I only pass a new TimeSegment object to the view, I can't populate the dropdownlists with Projects, Tasks and Consultants.
And oppositely, if I only pass the entire model, how would I bind a textbox to a new TimeSegment to be updated in the database?
I feel like I need to send both a new TimeSegment object and the entire model to do this, but then I have no idea how I would access it (there's only that one "Model" to access from the view). Also, back in the controller after a submit, how would the controller know what to update?
I'm sure I'm just thoroughly confused still by the MVC way of thinking, but I would really appreciate it if someone could clarify this for me and tell me (as pedagogically as possible) what to do to solve this.
Okay, I will give it a shot.
MVC is not hard, but you do have to alter your way of thinking a bit. In MVC you have the Models (your data layer[s]), the Views and the Controllers.
Before we continue, I make the assumptions with my examples below that you are using LINQ to SQL for you data access layer (Model), and I have labeled it as dc.
The Controllers fetch and format the data out of the Models and hand it off to the Views to display. So lets start with your first view which would be the view to create a TimeSegment.
[HttpGet]
public ActionResult CreateTimeSegment() {
return View(new TimeSegmentView {
Consultants = dc.Consultants.ToList(),
Projects = dc.Projects.ToList(),
Tasks = dc.Tasks.ToList()
});
}
This action will create a TimeSegmentView object and pass that to the View as its Model. Keep in mind that this action is decorated with [HttpGet]. TimeSegmentView` is a container class for the objects you need to pass to the view to create your UI and it looks like this:
public class TimeSegmentView {
public IList<Consultant> Consultants { get; set; }
public IList<Project> Projects { get; set; }
public IList<Task> Tasks { get; set; }
public TimeSegment TimeSegment { get; set; }
}
NOTE: I'm not using the TimeSegment property yet, it's further down...
In the view make sure you have it inherit from TimeSegmentView. Assuming that you're following the default MVC project structure and with me taking the liberty to add a Views folder into the Models folder your full reference would look like this:
<%# Page Inherits="System.Web.Mvc.ViewPage<PROJECTNAME.Models.Views.TimeSegmentView>" %>
Now you've typed the view to that object and you can now interact with its properties. So, you can build a form such as:
<form action="/" method="post">
<p>
<label>Hours</label>
<input name="TimeSegment.Hours" />
</p>
<p>
<label>Date</label>
<input name="TimeSegment.Date" />
</p>
<p>
<label>Consultant</label>
<select name="TimeSegment.ConsultantID">
<% foreach (Consultant C in Model.Consultants) { %>
<option value="<%=C.ConsultantID%>"><%=C.ConsultantName%></option>
<% }; %>
</select>
</p>
<p>
<label>Project</label>
<select name="TimeSegment.ProjectID">
<% foreach (Project P in Model.Projects) { %>
<option value="<%=P.ProjectID%>"><%=P.ProjectName%></option>
<% }; %>
</select>
</p>
<p>
<label>Task</label>
<select name="TimeSegment.TaskID">
<% foreach (Task T in Model.Tasks) { %>
<option value="<%=T.TaskID%>"><%=T.TaskName%></option>
<% }; %>
</select>
</p>
</form>
As you can see it created 3 select fields and just performed loops in each of them to build up their values based off of the model.
Now, taking a submission of this form, we'll need to get the data and add it to our database with:
[HttpPost]
public RedirectToRouteResult CreateTimeSegment(
[Bind(Prefix = "TimeSegment", Include = "Hours,Date,ConsultantID,ProjectID,TaskID")] TimeSegment TimeSegment) {
dc.TimeSegments.InsertOnSubmit(TimeSegment);
dc.SubmitChanges();
return RedirectToAction("EditTimeSegment", new {
TimeSegmentID = TimeSegment.TimeSegmentID
});
}
Okay, first notice that I've named the action the same, but this one has an [HttpPost] decoration. I'm telling the action that I'm sending it a TimeSegment object and that I want it to bind the properties in the Include clause (this is mostly for security and validation). I then take the TimeSegment object I've passed in, add it to the data context, submit the changes and redirect. In this case I'm redirecting to another action to edit the object I just created passing in the new TimeSegmentID. You can redirect to what ever, this just felt appropriate to me...
[HttpGet]
public ActionResult EditTimeSegment(
int TimeSegmentID) {
return View(new TimeSegmentView {
Consultants = dc.Consultants.ToList(),
Projects = dc.Projects.ToList(),
Tasks = dc.Tasks.ToList(),
TimeSegment = dc.TimeSegments.Single(t => t.TimeSegmentID == TimeSegmentID)
});
}
In the edit action your doing the same thing as in the create action by building a new TimeSegmentView object and passing it to the view. The key difference here is that you're now populating the TimeSegment property. Your form would look something like this (shortened from above):
<form action="/<%=Model.TimeSegment.TimeSegmentID%>" method="post">
<p>
<label>Hours</label>
<input name="TimeSegment.Hours" value="<%=Model.TimeSegment.Hours%>" />
</p>
</form>
And your receiving action on the controller would look like this:
[HttpPost]
public RedirectToRouteResult EditTimeSegment(
int TimeSegmentID) {
TimeSegment TS = dc.TimeSegments.Single(t => t.TimeSegmentID == TimeSegmentID);
TryUpdateModel<TimeSegment>(TS, "TimeSegment", new string[5] {
"Hours", "Date", "ConsultantID", "ProjectID", "TaskID"
});
dc.SubmitChanges();
return RedirectToAction("EditTimeSegment", new {
TimeSegmentID = TimeSegment.TimeSegmentID
});
}
Lastly, if you want to display a list of TimeSegments you can do something like this:
[HttpGet]
public ActionResult ListTimeSegments() {
return View(new TimeSegmentsView {
TimeSegments = dc.TimeSegments.ToList()
});
}
And TimeSegmentsView looks like this:
public class TimeSegmentsView {
public IList<TimeSegment> TimeSegments { get; set; }
}
And in the View you'd want to do this:
<table>
<% foreach (TimeSegment TS in Model.TimeSegments) { %>
<tr>
<td><%=TS.Hours%></td>
<td><%=TS.Date%></td>
<td><%=TS.Project.ProjectName%></td>
<td><%=TS.Consultant.ConsultantName%></td>
<td><%=TS.Task.TaskName%></td>
</tr>
<% }; %>
</table>
I hope this is enough to give you a start. It's by no means complete, but its 5 AM and I haven't slept yet, so this will have to do for now (from me). Feel free to name your actions what you want, you don't have to stick to my naming conventions.
I would suggest however that you change the naming of the properties of your tables. For example when your writing the expressions like in the table above you'll have to do TS.Project.ProjectName and that's redundant. You're already accessing the Project property of TS through their relationship so you know you're only going to work with a Project. This then makes ProjectName a pointless blob of text re-describing the object your working with. Instead just use Name, and turn your expression to TS.Project.Name.
Anyway, just a suggestion, do what you like better. I'm passing out, so good night and happy Thanksgiving!
UPDATE
The process with collections is essentially the same as far as the controller side is conserned. It's the client side and the JavaScript that's more difficult to get going, so I'll assume that you have something established on that end.
So, here's how the controller would work. You pass in an array of TimeSegment and the model binder is smart enough to figure it out through the Prefix of your form elements.
<form action="/<%=Model.TimeSegment.TimeSegmentID%>" method="post">
<p>
<label>Hours</label>
<input name="TimeSegment[0].Hours" />
<!-- Notice the array in the prefix -->
</p>
<p>
<label>Hours</label>
<input name="TimeSegment[1].Hours" />
<!-- Notice the array in the prefix -->
</p>
</form>
And the controller:
[HttpPost]
public RedirectToRouteResult CreateTimeSegments(
[Bind(Prefix = "TimeSegment", Include = "Hours,Date,ConsultantID,ProjectID,TaskID")] TimeSegment[] TimeSegments) {
dc.TimeSegments.InsertAllOnSubmit(TimeSegments);
dc.SubmitChanges();
return RedirectToAction("ListTimeSegments");
}
And that's it. Of course you'll want to validate or do other stuff before sending to the database, but that's roughly all there is to it.
UPDATE 2
I believe you can do an IList<TimeSegment> instead of TimeSegment[] without issues, but as far as if it's better, that's up for debate. The way I look at it the browser still sends a virtual array to the server so having the action receive an array feels natural, but its up to you what you want to use.
So, a generic list action would look like this:
[HttpPost]
public RedirectToRouteResult CreateTimeSegments(
[Bind(Prefix = "TimeSegment", Include = "Hours,Date,ConsultantID,ProjectID,TaskID")] IList<TimeSegment> TimeSegments) {
dc.TimeSegments.InsertAllOnSubmit(TimeSegments);
dc.SubmitChanges();
return RedirectToAction("ListTimeSegments");
}
Keep in mind that I haven't used this (meaning the IList) before so I can't guarantee it will work, just speculating...
UPDATE 3
About what you want to do with the Consultant, it sound a lot like what I do with Cookies. I have a BaseView class which is the type used by the Site.Master and then all other views extend from it. In the BaseView I have a Cookie property which is always populated by each controller action. I then use that property to get the id of the currently authorized user.
So, in code it looks like this (using examples from one of my apps):
public class BaseView {
// Don't confuse with an HttpCookie, this is an object in my database...
public Cookie Cookie { get; set;}
}
public class EmployeeView : BaseView {
public Employee Employee { get; set; }
}
And with this, say I want to add a note to an employee, my form would look like this where I pass in a hidden field which is where your ConsultantID comes into play.
<form>
<input type="hidden" name="Note.AuthorId" value="<%=Model.Cookie.EmployeeId%>" />
<!-- other fields -->
</form>
Hope this helps.