Phema.Validation 3.0.7

Phema.Validation

C# strongly typed expression-based validation library for .NET built on extension methods

Installation

$> dotnet add package Phema.Validation

Usage (example)

// Add `IValidationContext` as scoped service
services.AddValidation(options => ...);

// Get or inject
var validationContext = serviceProvider.GetRequiredService<IValidationContext>();

// Validation key will be `Name`
validationContext.When(person, p => p.Name)
  .Is(name => name == null)
  .AddError("Name must be set");

// Validation key will be `Address.Locations[0].Latitude`
validationContext.When(person, p => p.Address.Locations[0].Latitude)
  .Is(latitude => ...custom check...)
  .AddError("Some custom check failed");

// Override validation parts with `DataMemberAttribute`
[DataMember(Name = "name")]
public string Name { get; set; }

Validation conditions

// Check for Phema.Validation.Conditions namespace
validationContext.When(person, p => p.Name)
  .IsNullOrWhitespace()
  .AddError("Name must be set");

// Use multiple conditions (joined with OR)
validationContext.When(person, p => p.Name)
  .IsNull()
  .HasLengthGreater(20)
  // .IsNotNull()
  // .IsEqual()
  // .IsMatch(regex)
  .AddError("Name is invalid");

Validation details

// Null if valid
var validationDetails = validationContext.When(person, p => p.Age)
  .IsNull()
  .AddError("Age must be set");

// Use deconstruction
var (key, message) = validationContext.When(person, p => p.Age)
  .IsNull()
  .AddError("Age must be set");

Check validation

// Override default ValidationSeverity
validationContext.ValidationSeverity = ValidationSeverity.Warning;

// Throw exception when details severity greater than ValidationContext.ValidationSeverity
validationContext.When(person, p => p.Address)
  .IsNull()
  .AddFatal("Address is not presented!!!"); // If invalid throw ValidationConditionException

// Check if context is valid
validationContext.IsValid();
validationContext.EnsureIsValid(); // If invalid throw ValidationContextException

// Check concrete validation details
validationContext.IsValid(person, p => p.Age);
validationContext.EnsureIsValid(person, p => p.Age);

Validation scopes

• Use scopes when you need to have:
  • Same nested validation path multiple times
  • Empty validation details collection (syncing with parent context/scope)
  • ValidationSeverity override

// Validation key will be `Child.*ValidationPart*`
ValidateChild(validationContext.CreateScope(parent, p => p.Child))

// Validation key will be `Address.Locations[0].*ValidationPart*`
ValidateLocation(validationContext.CreateScope(person, p => p.Address.Locations[0]))

High performance with non-expression constructions

validationContext.When("key", value)
  .IsNull()
  .AddError("Value is null");

validationContext.CreateScope("key");

validationContext.IsValid("key");
validationContext.EnsureIsValid("key");

Benchmarks (i7 9700k 3.60 GHz, 16Gb 3400 MHz)

• Simpler expression = less costs
• Try to use non-expression extensions in hot paths
• Use CreateScope to not to repeat chained member calls (x => x.Property1.Property2[0].Property3)
• Expression-based When extensions use expression compilation to get value (Invoke)
• Composite indexers x => x.Collection[indexProvider.Parsed.Index] use expression compilation (DynamicInvoke)

Non-expression validation

Expression validation