How do Razor templates display ViewBag if?

In Razor templates, the ViewBag is a dynamic property that allows you to pass data from your controller to your view. When you need to conditionally display content based on the values in the ViewBag, you can use standard C# conditional statements within your Razor syntax.

Here's how you can use if statements with ViewBag in Razor:

1. Basic If Statement:

- You can use a simple if statement to check a boolean value or any other condition in the ViewBag.

@if (ViewBag.ShowMessage == true)
{
  <p class="qa-text">This message is displayed because ViewBag.ShowMessage is true.</p>
}

2. If-Else Statement:

- You can use an if-else statement to display different content based on the condition.

@if (ViewBag.UserRole == "Admin")
{
  <p class="qa-text">Welcome, Administrator!</p>
}
else
{
  <p class="qa-text">Welcome, User!</p>
}

3. Checking for Null or Empty Values:

- It's important to check if a ViewBag property exists and is not null before using it, especially if it's optional.

@if (ViewBag.UserName != null && !string.IsNullOrEmpty(ViewBag.UserName.ToString()))
{
  <p class="qa-text">Hello, @ViewBag.UserName!</p>
}
else
{
  <p class="qa-text">Hello, Guest!</p>
}

4. Using Ternary Operator:

- For simple conditions, you can use the ternary operator for a more concise syntax.

<p class="qa-text">Status: @(ViewBag.IsActive == true ? "Active" : "Inactive")</p>

5. Multiple Conditions:

- You can combine multiple conditions using logical operators like && (AND) and || (OR).

@if (ViewBag.IsLoggedIn == true && ViewBag.UserRole == "Admin")
{
  <p class="qa-text">Admin Panel Access Granted.</p>
}

Important Considerations:

- Always ensure that the ViewBag property you are accessing exists and has the expected type to avoid runtime errors.

- While ViewBag is convenient, consider using strongly-typed models for more complex data scenarios to improve type safety and maintainability.

By using these techniques, you can effectively display content conditionally in your Razor templates based on the values passed through the ViewBag.

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