Class ContainsNoNullItems

A rule which asserts that a collection contains no items that are null.

Inheritance
System.Object
ContainsNoNullItems
Implements
IRuleWithMessage<System.Collections.IEnumerable>
IRule<System.Collections.IEnumerable>
IGetsFailureMessage<System.Collections.IEnumerable>
Inherited Members
System.Object.Equals(System.Object)
System.Object.Equals(System.Object, System.Object)
System.Object.GetHashCode()
System.Object.GetType()
System.Object.MemberwiseClone()
System.Object.ReferenceEquals(System.Object, System.Object)
System.Object.ToString()
Namespace: CSF.Validation.Rules
Assembly: CSF.Validation.StandardRules.dll
Syntax
public class ContainsNoNullItems : IRuleWithMessage<IEnumerable>, IRule<IEnumerable>, IGetsFailureMessage<IEnumerable>
Remarks

This rule, used upon an System.Collections.IEnumerable, will result in enumerating the complete collection, testing every item to verify that it is not null. Beware of this behaviour when validating an System.Linq.IQueryable<T>, as it will lead to enumerating the queryable. Instead, prefer the generic ContainsNoNullItems<T> which has an overload specifically design to work with queryable objects.

Using this rule to get a failure message does not result in eumerating the collection a second time. The number of null items is recorded and stored in Data, this is then reused when creating the message, if available.

Methods

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GetFailureMessageAsync(IEnumerable, ValidationRuleResult, CancellationToken)

Gets the validation failure message for the specified result.

Declaration
public ValueTask<string> GetFailureMessageAsync(IEnumerable value, ValidationRuleResult result, CancellationToken token = default(CancellationToken))
Parameters
Type Name Description
System.Collections.IEnumerable value
ValidationRuleResult result

A validation result, typically indicating failure.
System.Threading.CancellationToken token

An optional cancellation token.
Returns
Type Description
System.Threading.Tasks.ValueTask<System.String>

A human-readable message.
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GetResultAsync(IEnumerable, RuleContext, CancellationToken)

Performs the validation logic asynchronously and returns a task of RuleResult.

Declaration
public ValueTask<RuleResult> GetResultAsync(IEnumerable validated, RuleContext context, CancellationToken token = default(CancellationToken))
Parameters
Type Name Description
System.Collections.IEnumerable validated
RuleContext context

Contextual information about the validation
System.Threading.CancellationToken token

An object which may be used to cancel the process
Returns
Type Description
System.Threading.Tasks.ValueTask<RuleResult>

A task which provides a result object, indicating the result of validation
Remarks

This method receives the value to be validated as well as an object which represents the context in which this rule is running. It should return a task of RuleResult.

In order to create the result object, particularly if your rule logic will run synchronously, consider using the CommonResults class via using static CSF.Validation.Rules.CommonResults; in your rule logic. The common results class has helper methods such as PassAsync(IDictionary<String, Object>) and FailAsync(IDictionary<String, Object>) which include optimisations for flyweight task instances that avoid allocating additional resources needlessly.

It is acceptable to throw an uncaught exception from this method, as the validation framework will catch it and automatically convert it into an error result. Generally, developers do not need to manually return a result of outcome Errored manually. This would be appropriate only in an unusual scenario that is considered an error, but which does not involve the throwing of an exception. Error results are generally harder for the consumer to deal with than failure results.

The context parameter may be used, amongst other things, to access 'ancestor' values. However, if this rule only needs access to an immediate parent value then consider using IRule<TValue, TParent> instead.

Exceptions
Type Condition
System.Exception

This method may raise any exception type

Implements