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How to use async await in LINQ select?
I need to modify an existing program and it contains following code: var inputs = events.Select (async ev => await ProcessEventAsync (ev)) .Select (t => t.Result) .Where (i => i != null) .ToList (); But this seems very weird to me, first of all the use of async and await in the select.
Are there any asynchronous versions of the LINQ operator?
These counterparts to the standard, synchronous LINQ operators include ToListAsync, SingleAsync, AsAsyncEnumerable, etc.: Note that there are no async versions of some LINQ operators such as Where or OrderBy, because these only build up the LINQ expression tree and don’t cause the query to be executed in the database.
How to execute a LINQ asynchronously in EF Core?
In order to support executing LINQ queries asynchronously, EF Core provides a set of async extension methods which execute the query and return results. These counterparts to the standard, synchronous LINQ operators include ToListAsync, SingleAsync, AsAsyncEnumerable, etc.: var blogs = await context.Blogs.Where(b => b.Rating > 3).ToListAsync();
When to call lazy LINQ functions in C #?
Hence, as long as you call lazy LINQ functions the query isn’t executed. Only when you starte enumerating, the query is executed. Enumerating starts when you call foreach, or non-layzy LINQ functions like ToList (), Any (), FirstOrDefault (), Max (), etc.
Is the toenumerable in LINQ really bad?
There should be something bad, really bad about it. Does it? 🙂 The bad part is that ToEnumerable returns an IEnumerable that blocks for each element until it is produced by the IObservable it is called on.
Are there any asynchronous predicates in LINQ?
Unfortunately, LINQ doesn’t appear to support asynchronous predicates, so something like this doesn’t work: Is there a similarly convenient way to do this? Should the predicates execute in parallel, or in series?
Do you have to know the number of items in a collection to use LINQ?
Since it keeps the linked list trimmed to this number of items the entire time through iterating through the collection, it will only keep a copy of at most N items from the original collection. It does not require you to know the number of items in the original collection, nor iterate over it more than once.
Is there way to elide await in LINQ?
In this particular case we can’t elide the await (and simply return the Task directly) because the conversion to BalanceItemResource happens in in-memory Linq, not Line-to-Entities.
Is it time consuming to change the LINQ expression?
The nice thing about this lazyness, is that as long as you use only lazy functions, changing the LINQ expression is not time consuming. Only when you use non-lazy functions, you have to be aware of the impact. This query contains only lazy LINQ functions. After all these statement, the todoLists have not been accessed yet.
How does lazy LINQ work in C #?
Lazy LINQ functions will only change the Enumerator that IEnumerable.GetEnumerator () will return when you start enumerating. Hence, as long as you call lazy LINQ functions the query isn’t executed. Only when you starte enumerating, the query is executed.