CODEWITHSUNDEEP
c#winformsasync-awaitmongodb-.net-driverusing-statement
nogood
nogood

Reputation: 1320

Is my way of using MongoDB C# driver FindAsync flawed?

Still kind of new to C#. My code gives me the results I want, but I'm uncertain if I did implemented it in an OK way. Please elaborate if you feel like answering. My goal was to search for entries in my MongoDB via FindAsync. Here is my code for that:

public async Task<List<T>> SearchDocAsync<T, U>(string collection,
    string findFieldName, U findValue)
{
    var _collection = db.GetCollection<T>(collection);
    var filter = Builders<T>.Filter.Eq(findFieldName, findValue);
    var result = await (_collection.FindAsync(filter).Result.ToListAsync());
    return result;
}

And here is the way I call it in WinForms:

private async void BtnReadAll_Click(object sender, EventArgs e)
{
    var asyncResults = await myMongoAux.SearchDocAsync<MyTModel, string>(
        myCollectionName, "MyDBString", "TestString");
    foreach (var r in asyncResults)
    {
        RtxbxResult.Text += $"{r.MyDBInt}\t{r.MyDBString}\n";
    }
}

Is this safe? Shouldn't I be using a using (but how)? And I have read something about that you should use:

ConfigureAwait(false)

How and why?

Be so kind and help me out understand more. Thank you for your time. :)

Upvotes: 0

Views: 8572

Answers (2)

Paulo Morgado
Paulo Morgado

Reputation: 14846

You can't use ConfigureAwait(false) on that method because you need to be back to the captured synchronization context (UI thread) after the await.

ConfigureAwait FAQ

Upvotes: 3

JonasH
JonasH

Reputation: 36401

this looks odd

var result = await (_collection.FindAsync(filter).Result.ToListAsync());

It should probably be

var result = await ((await _collection.FindAsync(filter)).ToListAsync());

Using .Result for tasks will block until the task has completed. Due to the way threads work in UI applications this has a rather high chance of causing a deadlock. So it is recommended to avoid .Result and .Wait() unless you are sure that no deadlock can occur.

Upvotes: 6

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