Phema.Validation

A simple, lightweight, fluent and extensible validation library for .NET Core

Installation

$> dotnet add package Phema.Validation

Core concepts

• IValidationContext - Scoped service to store all validation details
• IValidationCondition - Contains a validation checks (e.g. Is(() => ...))
• IValidationDetail - When IValidationCondition is not valid adds to IValidationContext.ValidationDetails
• ValidationSeverity - Validation error level, used in IValidationContext.ValidationSeverity and IValidationDetail.ValidationSeverity
• IValidationScope - Is a nested validation context with validation path and severity override

Usage (ASP.NET Core, HostedService examples)

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

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

// Validation key will be `Name` using default validation part provider
validationContext.When(person, p => p.Name)
  .Is(name => name == null)
  .AddValidationDetail("Name must be set");

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

Validation conditions

• Monads are not composable, so Is and IsNot, IsNull and IsNotNull... duplication

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

// Use multiple conditions (joined with AND)
validationContext.When(person, p => p.Name)
  .IsNotNull()
  // AND
  .HasLengthGreater(20)
  // .IsNull()
  // .IsEqual()
  // .IsNotUrl()
  // .IsNotEmail()
  // .IsMatch(regex)
  .AddValidationDetail("Name should be less than 20");

// DateTime conditions
validationContext.When(task, t => t.DueDate)
  .IsNotUtc()
  .AddValidationDetail("Due date must be in Utc");

// Type checks
validationContext.When(person, p => p.Car)
  .IsType<Ferrari>(typed => typed.Is(ferarriCar => ...Some Ferrari specific checks...))
  .AddValidationDetail("You have Ferrari car, but ...");

Validation details

var validationDetails = validationContext
  .When(person, p => p.Age)
  // Validation check is failed, validation condition is valid
  .Is(() => false)
  .AddValidationDetail("Age must be set");

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

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

// Even more deconstruction!
var (key, message, isValid, severity) = validationContext
  .When(person, p => p.Age)
  .IsNull()
  .AddValidationDetail("Age must be set");

Check validation

// Throw exception when details severity greater than ValidationContext.ValidationSeverity
validationContext.When(person, p => p.Address)
  .IsNull()
  .AddValidationFatal("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.IsNotValid(person, p => p.Age);
validationContext.EnsureIsValid(person, p => p.Age);

Compose and reuse validation rules with extensions

• Call is allocation free
• Static checks

// Extensions
public static void ValidateCustomer(this IValidationContext validationContext, Customer customer)
{
  // Some checks
}

validationContext.ValidateCustomer(customer);

• Write your own middleware or validation components/validators on top of IValidationContext

Validation part resolvers

• ValidationPartResolver is a delegate, trying to get string valdiation part from MemberInfo
• Use built in resolvers with ValidationPartResolvers static class: Default, DataMember, PascalCase, CamelCase

// Configure DataMember validation part resolver
services.AddValidation(options =>
  options.WithValidationPartResolver(ValidationPartResolvers.DataMember));

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

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]))

// Override local scope ValidationSeverity
using (var scope = validationContext.CreateScope(person, p => p.Address, ValidationSeverity.Warning))
{
  // Some scope validation checks syncing with validationContext
}

High performance with non-expression constructions

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

validationContext.CreateScope("key", ValidationSeverity.Warning);

validationContext.IsValid("key");
validationContext.IsNotValid("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 with Is(value => ...) extensions use lazy expression compilation to get value (Invoke)

ValidationPartResolvers

Method	Mean	Error	StdDev	Median	Allocated
Default	1.307 us	0.0031 us	0.0903 us	1.309 us	936 B
DataMember_WithAttribute	6.904 us	0.0105 us	0.2985 us	6.909 us	2398 B
DataMember_WithoutAttribute	1.983 us	0.0050 us	0.1465 us	1.991 us	1430 B
PascalCase_Lower	1.604 us	0.0046 us	0.1333 us	1.572 us	1048 B
PascalCase	1.365 us	0.0038 us	0.1132 us	1.366 us	936 B
CamelCase_Upper	1.549 us	0.0035 us	0.0986 us	1.569 us	1040 B
CamelCase	1.432 us	0.0037 us	0.1092 us	1.434 us	936 B

Non-expression validation

Method	Mean	Error	StdDev	Median	Allocated
Simple	215.7 ns	0.9524 ns	27.52 ns	225.0 ns	266 B
CreateScope	119.7 ns	0.5997 ns	17.87 ns	128.1 ns	112 B
IsValid	219.3 ns	0.6558 ns	19.38 ns	228.1 ns	424 B
EnsureIsValid	218.2 ns	0.6113 ns	17.72 ns	225.0 ns	424 B

Expression validation

Method	Mean	Error	StdDev	Median	Allocated
SimpleExpression	1,216.5 ns	2.0927 ns	60.78 ns	1,231.2 ns	914 B
SimpleExpression_CompiledValue	1,437.8 ns	2.2016 ns	62.72 ns	1,456.2 ns	1010 B
ChainedExpression	1,680.5 ns	3.0921 ns	90.31 ns	1,712.5 ns	1258 B
ChainedExpression_CompiledValue	1,908.5 ns	3.4080 ns	99.13 ns	1,940.6 ns	1354 B
ArrayAccessExpression	1,766.2 ns	3.5956 ns	103.22 ns	1,803.1 ns	1410 B
ArrayAccessExpression_CompiledValue	2,002.5 ns	4.0274 ns	117.76 ns	2,056.2 ns	1506 B
ChainedArrayAccessExpression	2,312.1 ns	4.5806 ns	133.17 ns	2,368.8 ns	1770 B
ChainedArrayAccessExpression_CompiledValue	2,542.6 ns	5.6628 ns	164.75 ns	2,593.8 ns	1866 B
ChainedArrayAccess	3,998.3 ns	9.4951 ns	275.09 ns	4,078.1 ns	2715 B
ChainedArrayAccess_CompiledValue	4,669.4 ns	9.7369 ns	283.27 ns	4,790.6 ns	2802 B
CreateScope_SimpleExpression	1,050.5 ns	1.2892 ns	37.55 ns	1,053.1 ns	736 B
CreateScope_ChainedExpression	1,375.0 ns	1.3573 ns	39.32 ns	1,375.0 ns	1080 B
IsValid_Empty	113.1 ns	0.6117 ns	17.99 ns	121.9 ns	184 B
IsValid_Expression	1,155.1 ns	1.0107 ns	28.99 ns	1,150.0 ns	1048 B
EnsureIsValid_Expression	1,098.0 ns	1.1002 ns	31.19 ns	1,095.3 ns	1048 B