如何使用 Razor 在 C# 中传递数组

Question

This is my viewtrainees.cshtml.cs file snippets that contain the array code:

public class viewTraineeModel : PageModel
{
    public string[] traineeinfo { get; set; }
    (...)

In my OnGet():

string[] traineeinfo = new string[Convert.ToInt32(countnum)];

int i = 0;

while (trainees.Read())
{
    traineeinfo[i] = trainees["t3_win"].ToString();
    i++;
}

So everything is set in my array fine, I even tested it within the.cs file. However, when I pass the array or think I pass the array to the view it ALWAYS gives me an internal error.

I have tried on my viewtrainees.cshtml file:

@Model.traineeinfo[0]

And I get NullReferenceException: Object reference not set to an instance of an object. Error.

The head element of my code looks like this.

@page
@model T3_Landing.Pages.viewTraineeModel

@{
    ViewData["Title"] = "View Trainees";

    string[] traineeinfo = Model.traineeinfo as string[];    
}

I have tried it with and without re-initializing the string array as seen above. I really want this to work.

Just a note I can pass regular strings just fine using @Model.examplestring but never an array, list, or object.

Answer 1

It's hard to tell without the full context, but it looks like you're hiding the class member by declaring a local variable within OnGet() :

string[] traineeinfo = new string[Convert.ToInt32(countnum)];

This creates a local variable named traineeinfo that hides the class property (if that's the case I would expect a compiler warning). Since the class property is not set, you get a null reference exception in your Razor page.

Try just

traineeinfo = new string[Convert.ToInt32(countnum)];

I would also recommend using camel case to make it easier to read:

public string[] TraineeInfo { get; set; }

....

TraineeInfo = new string[Convert.ToInt32(countnum)];

Answer 2

Here on constructor, I think you may initialize string array for prevent null value.

public class viewTraineeModel : PageModel
{
public string[] traineeinfo { get; set; }
...

public viewTraineeModel()
{
traineeinfo=new string[0];
}

Answer 3

Please drop a screen shot or code snippet of how you're passing the data to your view from your controller method end. That will determine if you have the data you want to work with in your view in the first place.