How to Refresh a Main Razor Page from Sub-Components After an API Call in Blazor?

Refreshing a main Razor page from sub-components in Blazor after an API call requires a state management approach. Blazor's built-in change detection mechanism won't automatically update the parent component unless its data properties change. Here's how to implement a robust solution using a state/notification pattern:

To achieve this, we'll use a service to manage application state, injecting it into both the main page and its sub-components. The sub-components will trigger notifications in this service after API calls, prompting UI updates.

1. Create a State Management Service:

This service will hold the data and a mechanism to notify subscribers of changes. We'll use an EventCallback for this purpose.

using Microsoft.AspNetCore.Components;

public class StateService
{
    public event Action StateChanged;

    // Your application state data
    public string DataFromAPI { get; set; } = "";

    public void NotifyStateChanged()
    {
        StateChanged?.Invoke();
    }
}

2. Inject the Service into Components:

Inject the StateService into both your main Razor page and the sub-components that make API calls.

@inject StateService StateService // In both the main page and sub-components

3. API Call and State Update in Sub-Component:

In your sub-component, after a successful API call, update the StateService's data and notify of the change.

@code {
    protected override async Task OnInitializedAsync()
    {
        string apiData = await FetchDataFromAPI(); // Your API call
        StateService.DataFromAPI = apiData;
        StateService.NotifyStateChanged();
    }

    // ... your API call method ...
    private async Task<string> FetchDataFromAPI()
    {
        // Your API call logic here
        return await Task.FromResult("Data from API");
    }
}

4. Update the Main Razor Page:

In your main Razor page, display the data from the StateService. Blazor will automatically re-render this section when StateService.DataFromAPI changes because it's a property of a component.

@page "/"
@inject StateService StateService

<h1 id="Main-Page">Main Page</h1>
<p>@StateService.DataFromAPI</p>

<MySubComponent />

Important Considerations:

• Error Handling: Include proper error handling in your API calls within the sub-components.
• Complex State: For more complex applications, consider using a more sophisticated state management library like Fluxor or Redux.
• Asynchronous Operations: Ensure your API calls are handled asynchronously using async and await to prevent blocking the UI thread.

This pattern ensures that changes in any sub-component will trigger an update in the main page by updating the shared state and notifying the system of the change. The main page automatically re-renders because it's bound to the service's data. This avoids manual calls to StateHasChanged in the parent component, which is generally discouraged for this type of update.

The above is the detailed content of How to Refresh a Main Razor Page from Sub-Components After an API Call in Blazor?. For more information, please follow other related articles on the PHP Chinese website!