Two-way-binding for SupplyParameterFromQuery in Blazor

[zachneu]

Is there an existing issue for this?

• I have searched the existing issues

Is your feature request related to a problem? Please describe the problem.

Background

Blazor supports reading query string parameters using [SupplyParameterFromQuery], but there's currently no built-in way to reflect parameter changes back into the query string.

Problem

This makes it harder to:

• Keep URL state in sync with the UI

• Support shareable/bookmarkable/filterable views

• Avoid manual calls to NavigationManager.NavigateTo(...) every time a parameter changes

Proposal

Introduce optional support for two-way query string binding, possibly via:

• Convention-based binding (MyProp + MyPropChanged)

• A dedicated directive: @bind-query="Search"

This would:

• Populate SearchTerm from the query on load
• Update the query string automatically on changes (e.g., from input)

Notes

• Can use NavigationManager.NavigateTo(..., replace: true) internally to avoid history pollution
• Should avoid unnecessary updates by comparing current and new URLs

Alternatives Considered

Manual URL management is possible but adds a lot of boilerplate and makes query string integration less discoverable and consistent.

Impact

Would improve support for modern SPAs where the query string is used as UI state (filters, tabs, search, etc.) and make Blazor more intuitive.

Describe the solution you'd like

Example

`@page "/search"
@bind-query="SearchTerm"

<input @Bind="SearchTerm" />

@code {
[Parameter]
public string SearchTerm { get; set; }

[Parameter]
public EventCallback<string> SearchTermChanged { get; set; }

}`

Additional context

No response

[javiercn]

@zachneu thanks for contacting us.

[SupplyParameterFromQuery] properties are component parameters and using them for state is an anti-pattern as it interferes with the diffing system that we use, so this is not something we plan to do any time soon.

The best way to tackle this is using NavigateTo to update the URL and let that change flow down to the component, and not the other way around.

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