This is a part of a series of blog posts on data access with Dapper. To see the full list of posts, visit the Dapper Series Index Page. I want to focus specifically on the Dapper bits here but validation is really important. In a real-world scenario, you should be validating any data that is passed in to the server. I recommend using Fluent Validation. Inserting a single new record is really easy. The version of the ExecuteAsync method we used here accepts two parameters: a string containing the SQL statement to execute and an object containing the parameter values to bind to the statement.
In this case, it is an instance of the Aircraft class which has properties with names matching the parameters defined in the INSERT statement. For that, we will add the below code. When the above code is set, and the project is executed using Visual Studio, you will get the below output.
Net can delete existing records from a database. The below code snippet will be used to delete an existing record in our database. We have seen how we can use ASP. We also saw how we can read each row of the table display it on the web page.
There are methods available to link controls directly to different fields in the table. At the moment, only the below controls can be bound to an ASP. Net application. Here we will take a listbox example. Step 1 Construct the basic web form. From the toolbox in Visual Studio, drag and drop 2 components- labels and Listboxes. Then carry out the following substeps;. Step 2 The next step is to start connecting each listbox to the database table. Step 3 You will then be presented with a dialog box.
This can be used to create a new data source. The data source will represent a connection to the database. Step 4 The below screen will be prompted after choosing the new data source in the last step. Here we need to mention the type of data source we want to create. Step 5 Now we need to create a connection to our database. In the next screen, click on the New Connection button.
This section shows how to create a page that lets users add a new product to the Product database table. After a new product record is inserted, the page displays the updated table using the ListProducts.
The page includes validation to make sure that the data that the user enters is valid for the database. For example, code in the page makes sure that a value has been entered for all required columns. The body of the page contains an HTML form with three text boxes that let users enter a name, description, and price. When users click the Insert button, the code at the top of the page opens a connection to the SmallBakery.
You then get the values that the user has submitted by using the Request object and assign those values to local variables. The Validation helper checks that there is a value in each of the fields that you've registered. You can test whether all the fields passed validation by checking Validation. IsValid , which you typically do before you process the information you get from the user:. If all the columns validated none were empty , you go ahead and create a SQL statement to insert the data and then execute it as shown next:.
For the values to insert, you include parameter placeholders 0 , 1 , 2. As a security precaution, always pass values to a SQL statement using parameters, as you see in the preceding example. This gives you a chance to validate the user's data, plus it helps protect against attempts to send malicious commands to your database sometimes referred to as SQL injection attacks.
To execute the query, you use this statement, passing to it the variables that contain the values to substitute for the placeholders:. After the Insert Into statement has executed, you send the user to the page that lists the products using this line:.
If validation didn't succeed, you skip the insert. Instead, you have a helper in the page that can display the accumulated error messages if any :. Notice that the style block in the markup includes a CSS class definition named.
In this case, the CSS class specifies that validation summary errors are displayed in red and in bold, but you can define the. View the page in a browser. The page displays a form that's similar to the one that's shown in the following illustration. Click Insert. The page displays an error message, as shown in the following illustration. No new record is created. Fill the form out completely, and then click Insert.
This time, the ListProducts. After data has been entered into a table, you might need to update it. This procedure shows you how to create two pages that are similar to the ones you created for data insertion earlier. The first page displays products and lets users select one to change. The second page lets the users actually make the edits and save them.
Important In a production website, you typically restrict who's allowed to make changes to the data. For information about how to set up membership and about ways to authorize users to perform tasks on the site, see Adding Security and Membership to an ASP.
The only difference between this page and the ListProducts. When you click this link, it takes you to the UpdateProducts. The href attribute specifies the page to display when the user clicks the link. It also passes the Id value of the current row to the link. When the page runs, the page source might contain links like these:. When a user clicks one of these links, the resulting URL will look something like this:.
Next, you'll create the page that lets users actually update the data. The update page includes validation to validate the data that the user enters. The body of the page contains an HTML form where a product is displayed and where users can edit it. To get the product to display, you use this SQL statement:.
This will select the product whose ID matches the value that's passed in the 0 parameter. Because Id is the primary key and therefore must be unique, only one product record can ever be selected this way.
To get the ID value to pass to this Select statement, you can read the value that's passed to the page as part of the URL, using the following syntax:. To actually fetch the product record, you use the QuerySingle method, which will return just one record:.
The single row is returned into the row variable. You can get data out of each column and assign it to local variables like this:. In the markup for the form, these values are displayed automatically in individual text boxes by using embedded code like the following:. That part of the code displays the product record to be updated.
Once the record has been displayed, the user can edit individual columns. When the user submits the form by clicking the Update button, the code in the if IsPost block runs. This gets the user's values from the Request object, stores the values in variables, and validates that each column has been filled in.
If validation passes, the code creates the following SQL Update statement:. In a SQL Update statement, you specify each column to update and the value to set it to. In this code, the values are specified using the parameter placeholders 0 , 1 , 2 , and so on. As noted earlier, for security, you should always pass values to a SQL statement by using parameters. When you call the db. Execute method, you pass the variables that contain the values in the order that corresponds to the parameters in the SQL statement:.
After the Update statement has been executed, you call the following method in order to redirect the user back to the edit page:. The effect is that the user sees an updated listing of the data in the database and can edit another product. Run the EditProducts. The UpdateProducts. Make a change and click Update. The products list is shown again with your updated data. This section shows how to let users delete a product from the Product database table.
The example consists of two pages. In the first page, users select a record to delete.
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