<PackageReference Include="Polly" Version="5.8.0" />

FallbackTResultSyntaxAsync

public static class FallbackTResultSyntaxAsync
Fluent API for defining a Fallback Policy.
using Polly.Fallback; using Polly.Utilities; using System; using System.Collections.Generic; using System.Threading; using System.Threading.Tasks; namespace Polly { public static class FallbackTResultSyntaxAsync { public static FallbackPolicy<TResult> FallbackAsync<TResult>(this PolicyBuilder<TResult> policyBuilder, TResult fallbackValue) { Func<DelegateResult<TResult>, Task> onFallbackAsync = (DelegateResult<TResult> _) => TaskHelper.EmptyTask; return policyBuilder.FallbackAsync((CancellationToken ct) => TaskHelper.FromResult<TResult>(fallbackValue), onFallbackAsync); } public static FallbackPolicy<TResult> FallbackAsync<TResult>(this PolicyBuilder<TResult> policyBuilder, Func<CancellationToken, Task<TResult>> fallbackAction) { if (fallbackAction == null) throw new ArgumentNullException("fallbackAction"); Func<DelegateResult<TResult>, Task> onFallbackAsync = (DelegateResult<TResult> _) => TaskHelper.EmptyTask; return policyBuilder.FallbackAsync(fallbackAction, onFallbackAsync); } public static FallbackPolicy<TResult> FallbackAsync<TResult>(this PolicyBuilder<TResult> policyBuilder, TResult fallbackValue, Func<DelegateResult<TResult>, Task> onFallbackAsync) { if (onFallbackAsync == null) throw new ArgumentNullException("onFallbackAsync"); return policyBuilder.FallbackAsync((DelegateResult<TResult> outcome, Context ctx, CancellationToken ct) => TaskHelper.FromResult<TResult>(fallbackValue), (DelegateResult<TResult> outcome, Context context) => onFallbackAsync(outcome)); } public static FallbackPolicy<TResult> FallbackAsync<TResult>(this PolicyBuilder<TResult> policyBuilder, Func<CancellationToken, Task<TResult>> fallbackAction, Func<DelegateResult<TResult>, Task> onFallbackAsync) { if (fallbackAction == null) throw new ArgumentNullException("fallbackAction"); if (onFallbackAsync == null) throw new ArgumentNullException("onFallbackAsync"); return policyBuilder.FallbackAsync((DelegateResult<TResult> outcome, Context ctx, CancellationToken ct) => fallbackAction(ct), (DelegateResult<TResult> outcome, Context context) => onFallbackAsync(outcome)); } public static FallbackPolicy<TResult> FallbackAsync<TResult>(this PolicyBuilder<TResult> policyBuilder, TResult fallbackValue, Func<DelegateResult<TResult>, Context, Task> onFallbackAsync) { if (onFallbackAsync == null) throw new ArgumentNullException("onFallbackAsync"); return policyBuilder.FallbackAsync((DelegateResult<TResult> outcome, Context ctx, CancellationToken ct) => TaskHelper.FromResult<TResult>(fallbackValue), onFallbackAsync); } [Obsolete("This overload is deprecated and will be removed in a future release. Prefer the overload in which both fallbackAction and onFallbackAsync take a Context input parameter.")] public static FallbackPolicy<TResult> FallbackAsync<TResult>(this PolicyBuilder<TResult> policyBuilder, Func<CancellationToken, Task<TResult>> fallbackAction, Func<DelegateResult<TResult>, Context, Task> onFallbackAsync) { if (fallbackAction == null) throw new ArgumentNullException("fallbackAction"); if (onFallbackAsync == null) throw new ArgumentNullException("onFallbackAsync"); return policyBuilder.FallbackAsync((DelegateResult<TResult> outcome, Context ctx, CancellationToken ct) => fallbackAction(ct), onFallbackAsync); } public static FallbackPolicy<TResult> FallbackAsync<TResult>(this PolicyBuilder<TResult> policyBuilder, Func<Context, CancellationToken, Task<TResult>> fallbackAction, Func<DelegateResult<TResult>, Context, Task> onFallbackAsync) { if (fallbackAction == null) throw new ArgumentNullException("fallbackAction"); if (onFallbackAsync == null) throw new ArgumentNullException("onFallbackAsync"); return policyBuilder.FallbackAsync((DelegateResult<TResult> outcome, Context ctx, CancellationToken ct) => fallbackAction(ctx, ct), onFallbackAsync); } public static FallbackPolicy<TResult> FallbackAsync<TResult>(this PolicyBuilder<TResult> policyBuilder, Func<DelegateResult<TResult>, Context, CancellationToken, Task<TResult>> fallbackAction, Func<DelegateResult<TResult>, Context, Task> onFallbackAsync) { if (fallbackAction == null) throw new ArgumentNullException("fallbackAction"); if (onFallbackAsync == null) throw new ArgumentNullException("onFallbackAsync"); return new FallbackPolicy<TResult>((Func<Func<Context, CancellationToken, Task<TResult>>, Context, CancellationToken, bool, Task<TResult>>)((Func<Context, CancellationToken, Task<TResult>> action, Context context, CancellationToken cancellationToken, bool continueOnCapturedContext) => FallbackEngine.ImplementationAsync<TResult>(action, context, (IEnumerable<ExceptionPredicate>)policyBuilder.ExceptionPredicates, (IEnumerable<ResultPredicate<TResult>>)policyBuilder.ResultPredicates, onFallbackAsync, fallbackAction, cancellationToken, continueOnCapturedContext)), (IEnumerable<ExceptionPredicate>)policyBuilder.ExceptionPredicates, (IEnumerable<ResultPredicate<TResult>>)policyBuilder.ResultPredicates); } } }