ASP.NET Core MVC with Razor Pages (can't return object from a different model)

Question

I'm making a call to Azure tables in a method I've created as part of the Razor page model (cs) file. The results are of type TenantEntityModel. I'd like to simply display those results in my view.

Is it possible to do this and if so, what needs to be in my Razor page model?

The method in my Razor model has the following call:

TenantEntityModel Result = await azureTableConnection.TenantLookupAsync(azureTableConnection, domainName, id);

I thought I could just use @Model.Result.DomainName in the view however there is no reference to this object as Result didn't exist in my Razor model. So I tried adding it to my Razor model as:

public TenantEntityModel Result { get; }

This allows me to access the properties of the Result in my Razor view. If I put a break point before the return Page() statement I can see the Result object has the properties I'm after. However when the view is rendered, the Model object's Result property is null and I get:

NullReferenceException: Object reference not set to an instance of an object.

I've also tried adding BindProperty as follows:

[BindProperty]
public TenantEntityModel Result { get; }

...but that didn't work either. So I'm at a loss on how to take the results of a query, populate an object with a model from a different class, then render a page with the results of that object.

View code:

@page
@model ApiKeyModel
@if (@Model.Result.ApiKey == null)
            {
                //show the button
                <button name="CreateApiKey" type="submit" class="btn btn-primary">Create new API Key</button>
            }

Controller code:

public class ApiKeyModel : PageModel
{
    private readonly UserManager<UserRegistrationExtension> _userManager;
    private readonly ILogger<PersonalDataModel> _logger;

    [BindProperty]
    public TenantEntityModel Result { get; set; }

    public ApiKeyModel(
        UserManager<UserRegistrationExtension> userManager,
        ILogger<PersonalDataModel> logger)
    {
        _userManager = userManager;
        _logger = logger;
    }

    public async Task<IActionResult> OnGet()
    {
        // need to validate if account exists first
        var user = await _userManager.GetUserAsync(User);
        if (user == null)
        {
            return NotFound($"Unable to load user with ID '{_userManager.GetUserId(User)}'.");
        }

        var domainName = user.Office365DomainName;
        var id = user.Id;
        AzureTableConnection azureTableConnection = new AzureTableConnection();
        TenantEntityModel Result = await azureTableConnection.TenantLookupAsync(azureTableConnection, domainName, id);

        return Page();
    }

edited. Just curious...does the 'controller code' in a Razor page consist of the 'code behind' of the view page? If so, where is the 'model'? Might be a dumb question but I thought Razor pages stuffed everything in a .cs file (controller and model). — Jason Shave
– Jason Shave, Commented Sep 24, 2018 at 1:37
Sorry, you are right, I forgot that this is Razor Pages in ASP.NET Core — jegtugado
– jegtugado, Commented Sep 24, 2018 at 1:56

jegtugado · Accepted Answer · 2018-09-24 03:48:50Z

2

Change your PageModel code to this. You were creating a local variable TenantEntityModel Result instead of assigning value to your property.

public class ApiKeyModel : PageModel
{
    private readonly UserManager<UserRegistrationExtension> _userManager;
    private readonly ILogger<PersonalDataModel> _logger;

    [BindProperty]
    public TenantEntityModel Result { get; set; }

    public ApiKeyModel(
        UserManager<UserRegistrationExtension> userManager,
        ILogger<PersonalDataModel> logger)
    {
        _userManager = userManager;
        _logger = logger;
    }

    public async Task<IActionResult> OnGet()
    {
        // need to validate if account exists first
        var user = await _userManager.GetUserAsync(User);
        if (user == null)
        {
            return NotFound($"Unable to load user with ID '{_userManager.GetUserId(User)}'.");
        }

        var domainName = user.Office365DomainName;
        var id = user.Id;
        AzureTableConnection azureTableConnection = new AzureTableConnection();
        Result = await azureTableConnection.TenantLookupAsync(azureTableConnection, domainName, id);

        return Page();
    }
}

edited Sep 24, 2018 at 3:48

answered Sep 24, 2018 at 1:57

jegtugado

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3 Comments

Jason Shave Over a year ago

That worked! Thank you John!! That makes sense. So there is no need to put the class name (model) in front of the variable I suppose. Is this because my class defines it's type earlier through the public TenantEntityModel Result {get; set;} piece?

jegtugado Over a year ago

Yes, that is the property accessible by your view code!

Ryan Vettese Over a year ago

"You were creating a local variable TenantEntityModel Result instead" - ugh! This tripped me up for a couple hours just now. Doh! :)

Edward · Accepted Answer · 2018-09-24 01:52:10Z

For passing model between View and PageModel in Razor Page, you need to set the value for the defined model public TenantEntityModel Result { get; set; } instead of defineing a new object TenantEntityModel Result.

Try to change OnGet() to:

public async Task<IActionResult> OnGet()
{
    // need to validate if account exists first
    var user = await _userManager.GetUserAsync(User);
    if (user == null)
    {
        return NotFound($"Unable to load user with ID '{_userManager.GetUserId(User)}'.");
    }

    var domainName = user.Office365DomainName;
    var id = user.Id;
    AzureTableConnection azureTableConnection = new AzureTableConnection();
    Result = await azureTableConnection.TenantLookupAsync(azureTableConnection, domainName, id);

    return Page();
}

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