Could not load from page that was just created. #4551

Yari27 · 2023-07-18T17:04:14Z

Yari27
Jul 18, 2023

Is there an existing issue for this?

I have searched both open/closed issues, no issue already exists.

CefSharp Version

114.2.120

Operating System

Windows 10

Architecture

x64

.Net Version

.Net.4.8

Implementation

WPF

Reproduction Steps

private string address;
private string filePath = @"C:\Users\user\OneDrive\Documents\index.html";

public string Address
        {
            get => address;
            set
            {
                if (value != address)
                {
                    address = value;
                    OnPropertyChanged();
                }
            }
        }

//First try - File not exist.
Address = $"file:///{filePath}"; 

//Second try - The file has been created
OnPropertyChanged(nameof(Address));

Expected behavior

First attempt to load page from file (file does not exist)
nothing loads.
Second attempt to load the page (file already exists)
the page has been loaded

Actual behavior

First attempt to load page from file (file does not exist)
nothing loads.
Second attempt to load the page (file already exists)
does not load the page from the given file. (Page source is empty <html><head></head><body></body></html>)

Regression?

No response

Known Workarounds

No response

Does this problem also occur in the CEF Sample Application

Not Tested

Other information

No response

amaitland · 2023-07-21T20:20:44Z

amaitland
Jul 21, 2023
Maintainer

Converted to discussion as this very unlikely a bug in CefSharp.

Assuming you've bound to the Address DependencyProperty then it's likely the behaviour you are seeing is expected.

Your firing the property change nofiticaiton without changing the actual value. From memory WPF ignores property change notifications when newValue and oldValue are equal. A quick look at the source yields.

// Change notifications are fired when the value actually changed

https://referencesource.microsoft.com/#WindowsBase/Base/System/Windows/DependencyObject.cs,1551

Your call is basically ignored by WPF, which is expected as you didn't change the value.

0 replies

Yari27 · 2023-07-22T14:15:20Z

Yari27
Jul 22, 2023
Author

Then why when I change the content of the page in the file from time to time, it refreshes, even though the address is the same all the time?

When the starting address is empty or the file does not exist, the page will never be displayed on subsequent refreshes.
But when the starting address is, for example, "www.google.com or an existing file, the page will always refresh when I call OnPropertyChanged(nameof(Address)) even for the same address;

2 replies

amaitland Jul 22, 2023
Maintainer

even though the address is the same all the time?

The Address (DependencyProperty) is updated to reflect the browsers internal changes of url.

https://github.com/cefsharp/CefSharp/blob/cefsharp/114/CefSharp.Wpf/ChromiumWebBrowser.cs#L1126

When the starting address is empty or the file does not exist, the page will never be displayed on subsequent refreshes.

WPF should only raise a change notification if the values are different
Depending on how your binding is configured you will get different results.

Calling OnPropertyChanged(nameof(Address)) is not the equivalent of calling Reload.

You can add a breakpoint in the changed handler to get a better understanding of what's going on.

https://github.com/cefsharp/CefSharp/blob/cefsharp/114/CefSharp.Wpf/ChromiumWebBrowser.cs#L1254-L1277

Yari27 Jul 23, 2023
Author

I have an MVVM application and I need 100% certainty/efficiency that the page will be refreshed every time for the same address, what property will give me that?

amaitland · 2023-07-28T20:35:35Z

amaitland
Jul 28, 2023
Maintainer

what property will give me that?

Reload is fundamentally a method, it doesn't map to a property directly. There is a ReloadCommand available for use in the view.

I have an MVVM application

Fundamentally you can call ChromiumWebBrowser.Reload

How you do this is really up to you and how your application is architected.

Send a message from the ViewModel to the View to reload the browser
Bind the WebBrowser to your ViewModel and access the browser via it's interface.
etc

If you are unsure then see what the recommended approach is for your MVVM framework.

2 replies

Yari27 Jul 29, 2023
Author

Thanks, it works great now, just what I was looking for.

P.S. The question is, if the Address is empty or null, the ReloadCommand should be active? What is Reloading?

amaitland Aug 2, 2023
Maintainer

You can look at the code to see the current behaviour. It's not something I've reviewed in a long time.

If you think there are improvements that would make sense to all users (not just your own scenario) then by all means submit a PR.

Provide feedback

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Could not load from page that was just created. #4551

Yari27 Jul 18, 2023

Is there an existing issue for this?

CefSharp Version

Operating System

Architecture

.Net Version

Implementation

Reproduction Steps

Expected behavior

Actual behavior

Regression?

Known Workarounds

Does this problem also occur in the CEF Sample Application

Other information

Replies: 3 comments · 4 replies

amaitland Jul 21, 2023 Maintainer

Yari27 Jul 22, 2023 Author

amaitland Jul 22, 2023 Maintainer

Yari27 Jul 23, 2023 Author

amaitland Jul 28, 2023 Maintainer

Yari27 Jul 29, 2023 Author

amaitland Aug 2, 2023 Maintainer

Yari27
Jul 18, 2023

Replies: 3 comments 4 replies

amaitland
Jul 21, 2023
Maintainer

Yari27
Jul 22, 2023
Author

amaitland Jul 22, 2023
Maintainer

Yari27 Jul 23, 2023
Author

amaitland
Jul 28, 2023
Maintainer

Yari27 Jul 29, 2023
Author

amaitland Aug 2, 2023
Maintainer