AsyncLinqIterator<TResult>

Namespace: SnowBank.Linq.Async.Iterators · class

Implements: IAsyncLinqQuery<TResult>, IAsyncQuery<TResult>, IAsyncEnumerable<TResult>, IAsyncEnumerator<TResult>, IAsyncDisposable

Base class for all async iterators

Properties

Cancellation

CancellationToken Cancellation { get; }

Cancellation token that should be used by all async operations performed in the context of this query

This token is controlled by the source (usually a transaction or other transient scope)

Current

TResult Current { get; }

Methods

AllAsync

Task<bool> AllAsync(Func<TResult, bool> predicate)

Task<bool> AllAsync(Func<TResult, CancellationToken, Task<bool>> predicate)

AnyAsync

Task<bool> AnyAsync()

Returns true if the range query yields at least one element, or false if there was no result.

Task<bool> AnyAsync(Func<TResult, bool> predicate)

Task<bool> AnyAsync(Func<TResult, CancellationToken, Task<bool>> predicate)

CountAsync

Task<int> CountAsync()

Returns the number of elements returned by this query.

Task<int> CountAsync(Func<TResult, bool> predicate)

Returns the number of elements returned by this query that match the given predicate.

Task<int> CountAsync(Func<TResult, CancellationToken, Task<bool>> predicate)

Returns the number of elements returned by this query that match the given predicate.

DisposeAsync

ValueTask DisposeAsync()

ExecuteAsync

Task ExecuteAsync(Action<TResult> handler)

Execute an action on the result of this async sequence

Task ExecuteAsync(Func<TResult, CancellationToken, Task> handler)

Task ExecuteAsync<TState>(TState state, Action<TState, TResult> handler)

Execute an action on the result of this async sequence

Task<TAggregate> ExecuteAsync<TAggregate>(TAggregate seed, Func<TAggregate, TResult, TAggregate> handler)

Execute an action on the result of this async sequence

Task ExecuteAsync<TState>(TState state, Func<TState, TResult, CancellationToken, Task> handler)

Task<TAggregate> ExecuteAsync<TState, TAggregate>(TState state, TAggregate seed, Func<TState, TAggregate, TResult, TAggregate> handler)

Execute an action on the result of this async sequence

FirstAsync

Task<TResult> FirstAsync()

Returns the first result of the query, or an exception if the query yields no result.

Task<TResult> FirstAsync(Func<TResult, bool> predicate)

Task<TResult> FirstAsync(Func<TResult, CancellationToken, Task<bool>> predicate)

FirstOrDefaultAsync

Task<TResult> FirstOrDefaultAsync()

Returns the first result of the query, or the default for this type if the query yields no results.

Task<TResult> FirstOrDefaultAsync(TResult defaultValue)

Returns the first result of the query, or the default for this type if the query yields no results.

Task<TResult> FirstOrDefaultAsync(Func<TResult, bool> predicate)

Returns the first result of the query, or the default for this type if the query yields no results.

Task<TResult> FirstOrDefaultAsync(Func<TResult, CancellationToken, Task<bool>> predicate)

Returns the first result of the query, or the default for this type if the query yields no results.

Task<TResult> FirstOrDefaultAsync(Func<TResult, bool> predicate, TResult defaultValue)

Task<TResult> FirstOrDefaultAsync(Func<TResult, CancellationToken, Task<bool>> predicate, TResult defaultValue)

GetAsyncEnumerator

IAsyncEnumerator<TResult> GetAsyncEnumerator(AsyncIterationHint mode)

Gets an asynchronous enumerator over the sequence.

Returns: Enumerator for asynchronous enumeration over the sequence.

LastAsync

Task<TResult> LastAsync()

Returns the last result of the query, or an exception if the query yields no result.

Task<TResult> LastAsync(Func<TResult, bool> predicate)

Task<TResult> LastAsync(Func<TResult, CancellationToken, Task<bool>> predicate)

LastOrDefaultAsync

Task<TResult> LastOrDefaultAsync()

Returns the last result of the query, or the default for this type if the query yields no results.

Task<TResult> LastOrDefaultAsync(TResult defaultValue)

Task<TResult> LastOrDefaultAsync(Func<TResult, bool> predicate)

Task<TResult> LastOrDefaultAsync(Func<TResult, CancellationToken, Task<bool>> predicate)

Task<TResult> LastOrDefaultAsync(Func<TResult, bool> predicate, TResult defaultValue)

Task<TResult> LastOrDefaultAsync(Func<TResult, CancellationToken, Task<bool>> predicate, TResult defaultValue)

MaxAsync

Task<TResult> MaxAsync(IComparer<TResult> comparer = null)

MinAsync

Task<TResult> MinAsync(IComparer<TResult> comparer = null)

MoveNextAsync

ValueTask<bool> MoveNextAsync()

Select

IAsyncLinqQuery<TNew> Select<TNew>(Func<TResult, TNew> selector)

Projects each element of the range results into a new form.

• selector — Function that is invoked for each source element, and will return the corresponding transformed element.

Returns: New range query that outputs the sequence of transformed elements

query.Select((kv) => $" = ")

IAsyncLinqQuery<TNew> Select<TNew>(Func<TResult, int, TNew> selector)

Projects each element of the range results into a new form.

• selector — Function that is invoked for each source element, and will return the corresponding transformed element.

Returns: New range query that outputs the sequence of transformed elements

query.Select((kv) => $" = ")

IAsyncLinqQuery<TNew> Select<TNew>(Func<TResult, CancellationToken, Task<TNew>> selector)

Projects each element of the range results into a new form.

• selector — Function that is invoked for each source element, and will return the corresponding transformed element.

Returns: New range query that outputs the sequence of transformed elements

query.Select((kv) => $" = ")

IAsyncLinqQuery<TNew> Select<TNew>(Func<TResult, int, CancellationToken, Task<TNew>> selector)

Projects each element of the range results into a new form.

• selector — Function that is invoked for each source element, and will return the corresponding transformed element.

Returns: New range query that outputs the sequence of transformed elements

query.Select((kv) => $" = ")

SelectMany

IAsyncLinqQuery<TNew> SelectMany<TNew>(Func<TResult, IEnumerable<TNew>> selector)

IAsyncLinqQuery<TNew> SelectMany<TNew>(Func<TResult, CancellationToken, Task<IEnumerable<TNew>>> selector)

IAsyncLinqQuery<TNew> SelectMany<TNew>(Func<TResult, IAsyncEnumerable<TNew>> selector)

IAsyncLinqQuery<TNew> SelectMany<TNew>(Func<TResult, IAsyncQuery<TNew>> selector)

IAsyncLinqQuery<TNew> SelectMany<TCollection, TNew>(Func<TResult, IEnumerable<TCollection>> collectionSelector, Func<TResult, TCollection, TNew> resultSelector)

IAsyncLinqQuery<TNew> SelectMany<TCollection, TNew>(Func<TResult, CancellationToken, Task<IEnumerable<TCollection>>> collectionSelector, Func<TResult, TCollection, TNew> resultSelector)

SingleAsync

Task<TResult> SingleAsync()

Returns the only result of the query, or an exception if it yields either zero, or more than one result.

Task<TResult> SingleAsync(Func<TResult, bool> predicate)

Task<TResult> SingleAsync(Func<TResult, CancellationToken, Task<bool>> predicate)

SingleOrDefaultAsync

Task<TResult> SingleOrDefaultAsync()

Returns the last result of the query, or the default for this type if the query yields no results.

Task<TResult> SingleOrDefaultAsync(TResult defaultValue)

Task<TResult> SingleOrDefaultAsync(Func<TResult, bool> predicate)

Task<TResult> SingleOrDefaultAsync(Func<TResult, CancellationToken, Task<bool>> predicate)

Task<TResult> SingleOrDefaultAsync(Func<TResult, bool> predicate, TResult defaultValue)

Task<TResult> SingleOrDefaultAsync(Func<TResult, CancellationToken, Task<bool>> predicate, TResult defaultValue)

Skip

IAsyncLinqQuery<TResult> Skip(int count)

SumAsync

Task<TResult> SumAsync()

Take

IAsyncLinqQuery<TResult> Take(int count)

IAsyncLinqQuery<TResult> Take(Range range)

TakeWhile

IAsyncLinqQuery<TResult> TakeWhile(Func<TResult, bool> condition)

ToArrayAsync

Task<TResult[]> ToArrayAsync()

Returns an array with all the elements of the range results

ToAsyncEnumerable

IAsyncEnumerable<TResult> ToAsyncEnumerable(AsyncIterationHint hint = 0)

Returns an IAsyncEnumerable view of this query

• hint — Hint passed to the source provider.

Returns: Sequence that will asynchronously return the results of this query.

For best performance, the caller should take care to provide a hint that matches how this query will be consumed downstream.

If the hint does not match, performance may be degraded. For example, if the caller will consumer this query using await foreach or ToListAsync, but uses Iterator, the provider may fetch small pages initially, before ramping up. The opposite is also true if the caller uses All but consumes the query using AnyAsync() or FirstOrDefaultAsync, the provider may fetch large pages and waste most of it except the first few elements.

ToDictionaryAsync

Task<Dictionary<TKey, TResult>> ToDictionaryAsync<TKey>(Func<TResult, TKey> keySelector, IEqualityComparer<TKey> comparer = null)

Task<Dictionary<TKey, TElement>> ToDictionaryAsync<TKey, TElement>(Func<TResult, TKey> keySelector, Func<TResult, TElement> elementSelector, IEqualityComparer<TKey> comparer = null)

Returns a dictionary with the decoded keys and values of the range results

ToHashSetAsync

Task<HashSet<TResult>> ToHashSetAsync(IEqualityComparer<TResult> comparer = null)

ToImmutableArrayAsync

Task<ImmutableArray<TResult>> ToImmutableArrayAsync()

ToListAsync

Task<List<TResult>> ToListAsync()

Returns a list of all the elements of the range results

Where

IAsyncLinqQuery<TResult> Where(Func<TResult, bool> predicate)

Filters the range results based on a predicate.

Caution: filtering occurs on the client side !

query.Where((kv) => kv.Key.StartsWith(prefix)) or query.Where((kv) => !kv.Value.IsNull)

IAsyncLinqQuery<TResult> Where(Func<TResult, int, bool> predicate)

Filters the range results based on a predicate.

Caution: filtering occurs on the client side !

query.Where((kv) => kv.Key.StartsWith(prefix)) or query.Where((kv) => !kv.Value.IsNull)

IAsyncLinqQuery<TResult> Where(Func<TResult, CancellationToken, Task<bool>> predicate)

Filters the range results based on a predicate.

Caution: filtering occurs on the client side !

query.Where((kv) => kv.Key.StartsWith(prefix)) or query.Where((kv) => !kv.Value.IsNull)

IAsyncLinqQuery<TResult> Where(Func<TResult, int, CancellationToken, Task<bool>> predicate)

Filters the range results based on a predicate.

Caution: filtering occurs on the client side !

query.Where((kv) => kv.Key.StartsWith(prefix)) or query.Where((kv) => !kv.Value.IsNull)