Class DataLoaderBase<TKey, TValue>

Namespace

GreenDonut

Assembly

GreenDonut.dll

A DataLoader creates a public API for loading data from a particular data back-end with unique keys such as the `id` column of a SQL table or document name in a MongoDB database, given a batch loading function. -- facebook

Each DataLoader instance contains a unique memoized cache. Use caution when used in long-lived applications or those which serve many users with different access permissions and consider creating a new instance per web request. -- facebook

This is an abstraction for all kind of DataLoaders.

public abstract class DataLoaderBase<TKey, TValue> : IDataLoader<TKey, TValue>, IDataLoader, IDisposable where TKey : notnull

Type Parameters

TKey

A key type.

TValue

A value type.

Inheritance

object

DataLoaderBase<TKey, TValue>

Implements

IDataLoader<TKey, TValue>

IDataLoader

IDisposable

Derived

BatchDataLoader<TKey, TValue>

CacheDataLoader<TKey, TValue>

GroupedDataLoader<TKey, TValue>

Inherited Members

object.GetType()

object.MemberwiseClone()

object.ToString()

object.Equals(object)

object.Equals(object, object)

object.ReferenceEquals(object, object)

object.GetHashCode()

Extension Methods

DataLoaderExtensions.LoadAsync(IDataLoader, object)

DataLoaderExtensions.LoadAsync(IDataLoader, params object[])

DataLoaderExtensions.LoadAsync(IDataLoader, CancellationToken, params object[])

DataLoaderExtensions.Set(IDataLoader, object, object?)

DataLoaderExtensions.LoadAsync<TKey, TValue>(IDataLoader<TKey, TValue>, params TKey[])

DataLoaderExtensions.LoadAsync<TKey, TValue>(IDataLoader<TKey, TValue>, CancellationToken, params TKey[])

DataLoaderExtensions.Set<TKey, TValue>(IDataLoader<TKey, TValue>, TKey, TValue)

Constructors

DataLoaderBase(IBatchScheduler, DataLoaderOptions?)

Initializes a new instance of the DataLoaderBase<TKey, TValue> class.

protected DataLoaderBase(IBatchScheduler batchScheduler, DataLoaderOptions? options = null)

Parameters

batchScheduler IBatchScheduler

A scheduler to tell the DataLoader when to dispatch buffered batches.

options DataLoaderOptions

An options object to configure the behavior of this particular DataLoaderBase<TKey, TValue>.

Exceptions

ArgumentNullException

Throws if options is null.

Properties

Cache

Gets access to the cache of this DataLoader.

protected ITaskCache? Cache { get; }

Property Value

ITaskCache

CacheKeyType

Gets the cache key type for this DataLoader.

protected virtual string CacheKeyType { get; }

Property Value

string

Methods

Clear()

public void Clear()

Dispose()

Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.

public void Dispose()

Dispose(bool)

Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.

protected virtual void Dispose(bool disposing)

Parameters

disposing bool

FetchAsync(IReadOnlyList<TKey>, Memory<Result<TValue>>, CancellationToken)

A batch loading function which has to be implemented for each individual DataLoader. For every provided key must be a result returned. Also to be mentioned is, the results must be returned in the exact same order the keys were provided.

protected abstract ValueTask FetchAsync(IReadOnlyList<TKey> keys, Memory<Result<TValue>> results, CancellationToken cancellationToken)

Parameters

keys IReadOnlyList<TKey>

A list of keys.

results Memory<Result<TValue>>

The resolved values which need to be in the exact same order as the keys were provided.

cancellationToken CancellationToken

A cancellation token.

Returns

ValueTask

A list of results which are in the exact same order as the provided keys.

GetCacheKeyType(Type)

A helper to create a cache key type for a DataLoader.

protected static string GetCacheKeyType(Type type)

Parameters

type Type

The DataLoader type.

Returns

string

Returns the DataLoader cache key.

GetCacheKeyType<TDataLoader>()

A helper to create a cache key type for a DataLoader.

protected static string GetCacheKeyType<TDataLoader>() where TDataLoader : IDataLoader

Returns

string

Returns the DataLoader cache key.

Type Parameters

TDataLoader

The DataLoader type.

LoadAsync(IReadOnlyCollection<TKey>, CancellationToken)

public Task<IReadOnlyList<TValue>> LoadAsync(IReadOnlyCollection<TKey> keys, CancellationToken cancellationToken = default)

Parameters

keys IReadOnlyCollection<TKey>

cancellationToken CancellationToken

Returns

Task<IReadOnlyList<TValue>>

LoadAsync(TKey, CancellationToken)

public Task<TValue> LoadAsync(TKey key, CancellationToken cancellationToken = default)

Parameters

key TKey

cancellationToken CancellationToken

Returns

Task<TValue>

Remove(TKey)

public void Remove(TKey key)

Parameters

key TKey

Set(TKey, Task<TValue>)

public void Set(TKey key, Task<TValue> value)

Parameters

key TKey

value Task<TValue>

TryAddToCache<TK, TV>(string, TK, TV)

A helper to adds an additional cache lookup to a resolved entity.

protected void TryAddToCache<TK, TV>(string cacheKeyType, TK key, TV value) where TK : notnull

Parameters

cacheKeyType string

The cache key type that shall be used to refer to the entity.

key TK

The key.

value TV

The value.

Type Parameters

TK

The key type.

TV

The value type.

TryAddToCache<TItem, TK, TV>(string, IEnumerable<TItem>, Func<TItem, TK>, Func<TItem, TV>)

A helper to add additional cache lookups to a resolved entity.

protected void TryAddToCache<TItem, TK, TV>(string cacheKeyType, IEnumerable<TItem> items, Func<TItem, TK> key, Func<TItem, TV> value) where TK : notnull

Parameters

cacheKeyType string

The cache key type that shall be used to refer to the entity.

items IEnumerable<TItem>

The items that shall be associated with other cache keys.

key Func<TItem, TK>

A delegate to create the key part.

value Func<TItem, TV>

A delegate to create the value that shall be associated.

Type Parameters

TItem

The item type.

TK

The key type.

TV

The value type.