},System.Func{System.DateTimeOffset,System.Boolean},System.Nullable{System.DateTimeOffset},System.Boolean,System.Func{--0,System.Boolean})} },System.Func{System.DateTimeOffset,System.Boolean},System.Nullable{System.DateTimeOffset},System.Boolean,System.Func{--0,System.Boolean})}

JsonSerializationMixin.GetAndFetchLatest(IBlobCache, string, Func>, Func?, DateTimeOffset?, bool, Func?) method¶

Defined in

Type: JsonSerializationMixin Namespace: Akavache Assembly: Akavache.Core.dll

Applies to

net9.0, net9.0-maccatalyst18.0, net9.0-macos15.0, net9.0-tvos18.0, net9.0-android35.0, net9.0-ios18.0, net8.0, net8.0-android34.0, net8.0-macos14.5, net8.0-ios18.0, net8.0-maccatalyst18.0, net8.0-macos15.0, net8.0-tvos18.0, net8.0-ios17.5, net8.0-maccatalyst17.5, net8.0-macos14.2, net8.0-tvos17.2, netstandard2.1, netstandard2.0

Overloads¶

1. public static IObservable<T?> GetAndFetchLatest<T>(this IBlobCache blobCache, string key, Func<IObservable<T>> fetchFunc, Func<DateTimeOffset, bool>? fetchPredicate = null, DateTimeOffset? absoluteExpiration = null, bool shouldInvalidateOnError = false, Func<T, bool>? cacheValidationPredicate = null)
2. public static IObservable<T?> GetAndFetchLatest<T>(this IBlobCache blobCache, string key, Func<Task<T>> fetchFunc, Func<DateTimeOffset, bool>? fetchPredicate = null, DateTimeOffset? absoluteExpiration = null, bool shouldInvalidateOnError = false, Func<T, bool>? cacheValidationPredicate = null)

1. Overload¶

public static IObservable<T?> GetAndFetchLatest<T>(this IBlobCache blobCache, string key, Func<IObservable<T>> fetchFunc, Func<DateTimeOffset, bool>? fetchPredicate = null, DateTimeOffset? absoluteExpiration = null, bool shouldInvalidateOnError = false, Func<T, bool>? cacheValidationPredicate = null)

View source

Summary: This method attempts to returned a cached value, while simultaneously calling a Func to return the latest value. When the latest data comes back, it replaces what was previously in the cache.

This method is best suited for loading dynamic data from the Internet, while still showing the user earlier data.

This method returns an IObservable that may return two results (first the cached data, then the latest data). Therefore, it's important for UI applications that in your Subscribe method, you write the code to merge the second result when it comes in.

This also means that await'ing this method is a Bad Idea™, always use Subscribe.

Type parameters

Name	Description
`T`	The type of item to get.

Parameters

Name	Type	Description
`blobCache`	[IBlobCache](#	The cache to get the item.
`key`	string	The key to store the returned result under.
`fetchFunc`	Func>	A method to fetch a observable.
`fetchPredicate = null`	Func?	An optional Func to determine whether the updated item should be fetched. If the cached version isn't found, this parameter is ignored and the item is always fetched.
`absoluteExpiration = null`	DateTimeOffset?	An optional expiration date.
`shouldInvalidateOnError = false`	bool	If this is true, the cache will be cleared when an exception occurs in fetchFunc.
`cacheValidationPredicate = null`	Func?	An optional Func to determine if the fetched value should be cached.

Returns: IObservable -- An Observable stream containing either one or two results (possibly a cached version, then the latest version).

2. Overload¶

public static IObservable<T?> GetAndFetchLatest<T>(this IBlobCache blobCache, string key, Func<Task<T>> fetchFunc, Func<DateTimeOffset, bool>? fetchPredicate = null, DateTimeOffset? absoluteExpiration = null, bool shouldInvalidateOnError = false, Func<T, bool>? cacheValidationPredicate = null)