I have the following model:
Customer:
ID
Name
Address
Phone
Fax
I added an Edit view based on the above model from the controller. I modified the Edit view to only allow edit on the Phone and Fax field (deleted the rest). When I submit it I get an error. It works if I leave the Edit view untouched (5 fields). However I only want to allow change in the last 2 fields.
I am lost, please help. Thanks :)
If you are using the MVC ability to populate your entity/class i.e. your action sig looks like this:
ViewResult MyAction(MyObject object) {
...
Save(MyObject);
}
then you'll need to make sure you include the other field, non-editable, either as visible information or using Html.Hidden within the form scope to ensure you have a fully populated object. Remember, the web is stateless and the server has no idea which record you were editing unless it has the keys to do so retrospectively.
The other option would be to retrieve the original object (for which you'll still need the primary key) from the database, update the fields from your form data and then submit the changes. We'd need to know the specific error to be able to help further, the code you are using would also be a great help.
Without knowing more I would guess it has something to do with binding null to a non null property in your model. Can you give me more details on the model, the error.
If you are using the default mvc model binder then it will only bind the fields you submit. So either submit as hidden or dont use a model binder and manually map the variable from Request.Form into a copy of the model you pulled form the db.
Related
My model does not really represent what my form is posting. Example my Orgs Model which holds orgs helps me generate a treeview the users selects several nodes of the orgs tree and submits a form. The form posts an array[] or org ids.
(maybe i'm doing this all wrong, please let me know tried binding to models and that was confusing when dealing with trees grids etc and using partial views and ajax returning partial views and editorfor's etc.. the default model binding was useless)
anyways back to my point, since I want to validate if any orgs get selected:
if (SelectedOrgs == null) //array[]
{
ModelState.AddModelError("OrgsNotSelected",IValidationErrors.OrgsNotSelected);
}
my question is how do i retrieve this random key that i just made up from my view? my model and even my viewmodel do not have an array for the selection this is just the result of the post.
I'm not sure what to do in the view to get the value for "OrgsNotSelected".
Thank you!
Bilal
If you were doing normal submit actions to your controller, you would need to use the ValidationSummary to display errors that are not attached to a specific property.
As you are using Ajax, you would be better off returning a json result from your controller and you can define this so that it includes your errors in a format you can use in the success function to display your messages.
I've understood that a viewmodel in MVC is supposed to reflect data on a single page rather than objects in the model. But should the viewmodel correspond to the data you want to show on that page or to the data you want back from that page? If we for example look at a login page then I just want username and password back in the post, but I might need more variables than that when displaying the login page (previous error messages etc).
Should the viewmodel then just contain username and password as parameters and the rest of the variables end up in viewbags. Or should the viewmodel contain all values I want to show even though I'm only interested in a few of them in the response.
What is best practice when using viewmodels?
All data that somehow interacts between the html and your server should be in a ViewModel.
This allows you to perform formatting and such outside your html and inside your ViewModel properties.
However, if your page contains a lot of controls or data, you may want to split it into multiple ViewModels (example one for the Get and one for the Post).
The post model may contain only data that you entered and needs to be validated.
I think it's best to put everything in the view-model. This keeps the code cleaner and makes discovery and maintenance easier as well. The view-model should be your primary mechanism here.
I would say only properties you need, in your case username and password. If you want to display error messages then that's what ModelState is for. You can always append any error messages to your ModelState:
ModelState.AddModelError("PropertyName", "Error Text")
Beyond that let's say you have a form that contains a list of categories that you need to pick one category from a drop down. In this case I usually attach that list to my model even though the only thing being submitted is the actual selected value. But this is a matter of preference, meaning I could also set a ViewBag to contain this SelectList of categories and then bind that to your DropDownList. I suppose it's better to place this in a model because ViewBag is dynamic and you will have to cast anything in the ViewBag into it's underlying type on your views.
I have a FormViewModel that handles different fields. Many of them have not to be presented to the user (such as modified_date, current_user_id) so I am using hidden fields to respect the FormViewModel structure. When submitted they are passed to the controller's action and correctly saved to the DB but I'm asking: is it the best way to do in ASPNET MVC? I would have preferred to define them in FormViewModel and using only the fields to be modified instead of showing also the non-modifiable as hidden fields.
Is there a better way to do it?
If these fields are not being touched by the user than I would do this;
Create a FormViewModel with only the fields that are relevant. Also the primary key.
The primary key still needs to be on the page me thinks.
Then in the controller you accept the FormViewModel as the argument, you then load the actual model and update, validate fields as required and save the model.
The above is simplistic and you'll have more layers but you should get the idea
I think you can do a few things to make your life a little easier:
Let the URL (and the routing mechanism) give you the id (the primary key of whatever you are trying to edit)
You can have a URL like '/Student/Edit/1' Routing will ensure that your Action method gets the id value directly.
Have 2 action methods to handle your request. One decorated with [HttpGet] to render the initial form to the user (where you just retrieve your object from the repository and pass it on to your View) and a [HttpPost] one to actually handle the post back from the user.
The second method could look something like:
[HttpPost]
[ActionName("Edit")]
public ActionResult EditPost(int id) {
...your code here...
}
Retrieve the actual record from the repository/store based on the id passed in.
Use the UpdateModel function to apply the changes to the database record and pass on the record back to your repository layer to store it back in the database.
However, in a real world application, you will probably want separation of concerns and decoupling between your repository and your view layer (ASP.NET MVC.)
If they are part of the model, the method you are using is perfectly fine. You even have a helper method in HtmlHelper.HiddenFor to output the hidden field for you. However, if the values are something like modified date or current user, you'd might be better suited passing those along from your controller to a DTO for your data layer. I'm making some assumptions about what you're doing for data access, though.
The risk with storing data which shouldn't be modified in hidden fields is that it can be modified using a browsers built in/extension developer tools. Upon post these changes will be saved to your database (if that's how you're handling the action).
To protect hidden fields you can use the MVC Security Extensions project https://mvcsecurity.codeplex.com.
Say the field you want to protect is Id...
On you controller post method add:
[ValidateAntiModelInjection("Id")]
Within your view add:
#Html.AntiModelInjectionFor(m => m.Id)
#Html.HiddenFor(m => m.Id)
On post your Id field will be validated.
Create a FormViewModel with only the fields that are relevant. Also the primary key.
The primary key still needs to be on the page me thinks.
Then in the controller you accept the FormViewModel as the argument, you then load the actual model and update, validate fields as required and save the model.
The above is simplistic and you'll have more layers but you should get the idea
Not sure if this question has already been asked.
I am developing an ASP .NET MVC 2 site. My view has a drop down where user can select which record to display for editing. When this drop down is changed, the field values for the currently selected record automatically get posted to the server and are saved in the session. In the response the server then returns a view for editing the newly selected record.
The problem I am having is that some of the field values from the previous record are being remembered when the new record is displayed.
In my view I have something like the following which is causing the problem:
<%= Html.TextBox("ActionTypeDetails.DisplayName",
Model.ActionTypeDetails.DisplayName) %>
Here I want the posted data to populate a parameter called ActionTypeDetails which has multiple properties including DisplayName.
My controller actions looks something like this:
public ActionResult EditActionType(Guid PluginEditID,
Guid? SelectedActionTypeID,
ActionTypeViewObj ActionTypeDetails)
I have tried changing my view to this:
<%= Html.TextBox("PostedActionTypeDetails.DisplayName",
Model.ActionTypeDetails.DisplayName) %>
And my controller action to this:
public ActionResult EditActionType(Guid PluginEditID,
Guid? SelectedActionTypeID,
ActionTypeViewObj PostedActionTypeDetails)
Yet it still exhibits the same problem. Can someone please explain the logic to why it works like this? What is the easiest workaround that would still allow me to use the built in model binding? I know I can clear the ModelState but this is not ideal as I want some of the other data on the form to be remembered.
If you post back to the same url, asp.net has mechanisms which preserve field values. More info can be found here.
Let's say I have a product object (pretty much empty) and I bind it to a Product view. Then I click update in the view. In my CustomModelBinder my bindingContext.Model is always null on the update request. Is there a recommended way of me retrieving the prior model at this point or do I always have to recreate it?
You have to recreate it from the form fields. The values you bound to the model for the GET are long gone.
perhaps im not understanding your needs to use a CustomModelBinder, but did u concider Data Annotations Model Binder yet?
it even comes with (serverside) validation based on simple statements like [Required] which u can put right inside your model, see this