I've a strange question I tought about for exercise that is not easy to explicate.
Suppose I've a form with some TDBEdit object. Nturally every TDBEdit object reference a database field.
Here a simple example:
When the user click the save button (the little disk icon on the top of the image) I make the data validation and, if data are correct, I register them into the database. Simple!
But my mental exercise is this:
all my data tables are included in a datamodule so what about if I would like to trasfer the data validation from the form to the datamodule?
Simple... it's enough to validate the table fields like this:
if (fAut_Cognome.Value = '') or (fAut_Nome.Value = '') then begin
...
Give error messsage
...
end;
But If the user doesn't leave the last TDBEdit object the relative database field is not valorized (for example while adding a new record to the table the database field will ane no value).
So my question is this: there is a way to validate data, from datamodule, even if the user doesn't leave the TDBEdit control?
You should plug the OnBeforeExit event of your TDBEdit to a method in the Datamodule. But as said in comments you will only test the control's value, not the DB field's value because not updated yet.
Related
MVC App
I am Creating a row for a table. It is defined as a Model.
The value of one of the fields is determined during a 'login' and is available for use.
That value should be displayed when the Create view is rendered on exit from the 'create(GET)' action and it should be saved as is to the data table by the POST.
So, bound to the model and prepopulated display element sounds like a job for Html.DisplayFor. Only it seems it is not.
How do we set the initial value in the DisplayFor statement. Barring that, how do we get data to the screen from the GET action for capture and saving during the Create(POST)?
I have to write more than one of these a year.
I can just pass a populated model instance in the return View(modelInstance).
That's my stupidity quota for the day, hopefully.
I have a form where a user enters an Id into a text field, and I then I validate said Id on the server. If the Id does not exist in the system, I display an error. I do this using async validation. If the Id does exist, however, the server will return a record from our database. I want to use those values to auto populate other fields in the form.
How would I accomplish this?
I did some searching and the closest solution I found was this other question on StackOverflow. The thing is, I want to change the value after my asycValidate logic has succeeded. I don't think I can trigger the action creator from inside asyncValidate, and I'm not aware of a way to have asyncValidate trigger a callback from inside the form component.
I was able to get it to work, by following the solutions discussed in the following thread: https://github.com/erikras/redux-form/issues/442
I'm creating a custom field called provinces where I have built a multi-select field. This field receives a JSON keyless object [3,4,5] from the database which I then apply to the input in getInput() in province.php. I have managed to this on the output, but I need to write any values selected back to the database.
Where can I get the values that are then passed back if the user selects other options (in the back-end form edit.php) in the multi-select?
In other words, where is the $_POST array received before either it is redirected back to the form (Save) or to the list page (Save & Close)?
Please correct me if I'm wrong.
Thanks in advance.
In the model for your form view, look for the function prepareTable. This is a good place to prepare/sanitize the data prior to saving.
If you want to process the data further after it is saved, you can use the function postSaveHook in your form controller.
Or you can of course also do something during save in the tables store function.
I got a silly general question...
If I generate a strongly typed view of an entity and chose "edit" as scaffolding, then the view does contain every column for that table. Changing and saving the values via setting it modifierd and call db.SaveChanges() does work in the controller. So far, so good.
But if I remove just one of that columns inside the view, then saving doesn't work anymore.
Is there a rule describing this? Is it only possible to make view with every column when wanting to save the model later on? I don't want to make 90 of 100 columns "hidden"...
PS: When editing a value in another table which is connected via Foreign Key (like customer.address.STREET) saving also does not work. Does everything of the entity ADDRESS has to be inside the view? I really don't get that.
Besides that: If I create my own ViewModel containing two entities: Do they also have to hold every column of both entities? This would be a whole bunch of traffic...
Answer is: You should not use the .Modified state. Instead using the UpdateModel method works fine without every field.
I have having a little trouble wrapping my head around the design pattern for MVC when the data type of the model property is very different than what I wish to display in a form. I am unsure of where the logic should go.
Realizing that I am not really sure how to ask the question I think I will explain it as a concrete example.
I have a table of Invoices with a second table containing the InvoiceDetails. Each of the InvoiceDetail items has an owner who is responsible for approving the charge. A given invoice has one or more people that will eventually sign off on all the detail rows so the invoice can be approved. The website is being built to provide the approval functionality.
In the database I am storing the employee id of the person who approved the line item. This schema provides me a model with a String property for the Approved column.
However, on the website I wish to provide a CheckBox for the employee to click to indicate they approve the line item.
I guess my question is this -- how do I handle this? The Model being passed to the View has a String property but the form value being passed back to the Controller will be of the CheckBox type. I see two possible ways...
1) Create a new Model object to represent the form fields...say something like FormInvoiceDetails...and have the business logic query the database and then convert the results to the other type. Then after being submitted, the form values need to be converted back so the original Model objects can be updated.
2) Pass the original InvoiceDetails collection to the View and have code there create render the CheckBox based on the value of the String property. I am still not sure how to handle the submission since I still need to map back the form values to the underlying database object.
Maybe there is a third way if not one of these two approaches?
To make the situation a bit more complicated (or maybe it doesn't), I am rendering the form to allow for the editing of multiple rows (i.e. collection).
Thanks for any insight anybody can provide.
You need a ViewModel, like #Justn Niessner suggests.
Your controller loads the complete model from the database, copies just the fields it needs into a ViewModel, and then hands the ViewModel off to the view for rendering.
I'd use Automapper to do the conversion from Model to ViewModel. It automates all the tedious thingA.x = thingY.x; code.
Here is an additional blog post going over in detail the use of ViewModels in the Nerd Dinner sample.
I believe what you are looking for is the ViewModel.
In cases where you are using a ViewModel, you design the ViewModel to match the exact data you need to show on your page.
You then use your Controller to populate and map your data from your Model in to your ViewModel and back again.
The Nerd Dinner ASP.NET MVC Example has some very good examples of using ViewModels.