Controller classes have a "ModelState" property collection which provides a way to indicate that errors exist with a model object being passed to a View. Error entries within the ModelState collection identify the name of the model property with the issue for example: "Title", "EventDate", or "ContactPhone" , and allow a human-friendly error message to be specified for example: "Title is required".
The UpdateModel helper method automatically populates the ModelState collection when it encounters errors while trying to assign form values to properties on the model object. When the UpdateModel method was unable to assign the string value "BOGUS" to it in the scenario above, the UpdateModel method added an entry to the ModelState collection indicating an assignment error had occurred with that property.
Developers can also write code to explicitly add error entries into the ModelState collection like we are doing below within our "catch" error handling block, which is populating the ModelState collection with entries based on the active Rule Violations in the Dinner object:. HTML helper methods - like Html.
TextBox - check the ModelState collection when rendering output. If an error for the item exists, they render the user-entered value and a CSS error class. For example, in our "Edit" view we are using the Html. TextBox helper method to render the EventDate of our Dinner object:. When the view was rendered in the error scenario, the Html. TextBox method checked the ModelState collection to see if there were any errors associated with the "EventDate" property of our Dinner object.
You can customize the appearance of the css error class to look however you want. ValidationMessage helper method can be used to output the ModelState error message associated with a particular model property:. ValidationMessage helper method also supports a second parameter that allows developers to override the error text message that is displayed:.
ValidationSummary helper method takes an optional string parameter — which defines a summary error message to display above the list of detailed errors:. We can make this code a little cleaner by adding a "ControllerHelpers" class to the NerdDinner project, and implement an "AddRuleViolations" extension method within it that adds a helper method to the ASP. This extension method can encapsulate the logic necessary to populate the ModelStateDictionary with a list of RuleViolation errors:.
The nice thing about our Edit implementation is that neither our Controller class nor our View template has to know anything about the specific validation or business rules being enforced by our Dinner model. We can add additional rules to our model in the future and do not have to make any code changes to our controller or view in order for them to be supported.
This provides us with the flexibility to easily evolve our application requirements in the future with a minimum of code changes. We've finished implementing the "Edit" behavior of our DinnersController class. Let's now move on to implement the "Create" support on it — which will enable users to add new Dinners.
Our implementation looks like:. The code above creates a new Dinner object, and assigns its EventDate property to be one week in the future. It then renders a View that is based on the new Dinner object. We can do this by right-clicking within the Create action method and selecting the "Add View" context menu command.
Within the "Add View" dialog we'll indicate that we are passing a Dinner object to the view template, and choose to auto-scaffold a "Create" template:. When we click the "Add" button, Visual Studio will save a new scaffold-based "Create.
Let's make a few changes to the default "create" scaffold file that was generated for us, and modify it up to look like below:.
One approach is to create a new Dinner object and then use the UpdateModel helper method like we did with the Edit action to populate it with the posted form values. We can then add it to our DinnerRepository, persist it to the database, and redirect the user to our Details action to show the newly created Dinner using the code below:.
Alternatively, we can use an approach where we have our Create action method take a Dinner object as a method parameter. NET MVC will then automatically instantiate a new Dinner object for us, populate its properties using the form inputs, and pass it to our action method:.
Our action method above verifies that the Dinner object has been successfully populated with the form post values by checking the ModelState. IsValid property. This will return false if there are input conversion issues for example: a string of "BOGUS" for the EventDate property , and if there are any issues our action method redisplays the form. If the input values are valid, then the action method attempts to add and save the new Dinner to the DinnerRepository.
Save method to raise an exception. Incorrect input or values will cause the create form to be redisplayed with the errors highlighted like below:. Notice how our Create form is honoring the exact same validation and business rules as our Edit form.
This is because our validation and business rules were defined in the model, and were not embedded within the UI or controller of the application. We will not have to change any code within either our Edit or Create action methods to automatically honor any new rules or modifications to existing ones. When we fix the input values and click the "Save" button again, our addition to the DinnerRepository will succeed, and a new Dinner will be added to the database.
Below is the implementation:. The action method attempts to retrieve the Dinner to be deleted. If the Dinner exists it renders a View based on the Dinner object. If the object doesn't exist or has already been deleted it returns a View that renders the "NotFound" view template we created earlier for our "Details" action method.
We can create the "Delete" view template by right-clicking within the Delete action method and selecting the "Add View" context menu command. Within the "Add View" dialog we'll indicate that we are passing a Dinner object to our view template as its model, and choose to create an empty template:.
When we click the "Add" button, Visual Studio will add a new "Delete. We'll add some HTML and code to the template to implement a delete confirmation screen like below:. The files that are saved on your computer after Windows update have a temporary utility, and are created specifically for the update phase. After that, they have no value since they are obsolete. Contrary to what you might think, if you do not delete these data, the speed of your PC can be affected, since the local disk is overloaded with unnecessary information.
Also, if you don't clear Windows update cache, your computer is prone to crashes or errors, because you may be keeping corrupted files, or because the system has been slowed down. If you have problems loading the latest Windows update, or you notice that your computer is slower, or you have lost space in the root that you need, do not worry, you just have to follow these simple steps so that in a few minutes your computer can resume its operation.
The "Services" window will be opened, locate where it says Windows Update , click and select the Stop option. On the left side, you will see the local disk of the computer, called Windows and which is identified with the letter C : , click to open.
Several folders will appear, you must scroll down until you find the Windows folder and proceed to open it. V2" and "SLS". Next, there is also a way to clear Windows update cache, which is through the Command Prompt. Learn here how to do it:. In addition, you must load either the list object itself or the itemCount property on the list object before executing the query.
If you want to retrieve both a start and end count of the list items, you must execute two queries and return the item count twice, as shown in the following modification of the previous example. SharePoint Client Object Creation. Skip to main content. This browser is no longer supported. Download Microsoft Edge More info. Contents Exit focus mode. In this article.
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