Roslyn analyser code fix - Disable preview option

Question

How do I disable the preview dialog that shows up after the light bulb in C# project?

Problem I have is, the RegisterCodeFixesAsync makes a call to database and increments the id and this is getting done twice (once during the preview and second time when the action is invoked), instead of incrementing just once, id increments twice

Answer 1

CodeAction has separate ComputePreviewOperationsAsync() and ComputeOperationsAsync(). Having them return different values is what I believe you're looking for. But if you use the common approach of calling CodeAction.Create(), both will return the same values.

What you can do instead is to create a custom class that inherits from CodeAction and overrides the methods the way you want. For example:

class NoPreviewCodeAction : CodeAction
{
    private readonly Func<CancellationToken, Task<Solution>> createChangedSolution;

    public override string Title { get; }

    public override string EquivalenceKey { get; }

    public NoPreviewCodeAction(
        string title, Func<CancellationToken, Task<Solution>> createChangedSolution,
        string equivalenceKey = null)
    {
        this.createChangedSolution = createChangedSolution;

        Title = title;
        EquivalenceKey = equivalenceKey;
    }

    protected override Task<IEnumerable<CodeActionOperation>> ComputePreviewOperationsAsync(
        CancellationToken cancellationToken)
    {
        return Task.FromResult(Enumerable.Empty<CodeActionOperation>());
    }

    protected override Task<Solution> GetChangedSolutionAsync(
        CancellationToken cancellationToken)
    {
        return createChangedSolution(cancellationToken);
    }
}

This version completely disables preview. Another option would be to make preview take a different path, e.g. querying the database for the next value, but not updating it.