Class ValidatorRuleBuilderExtensions

Namespace

REslava.Result

Assembly

REslava.Result.dll

Extension methods on ValidatorRuleBuilder<T> providing a native DSL for common validation rules (string, numeric, collection, null checks).

public static class ValidatorRuleBuilderExtensions

Inheritance

object

ValidatorRuleBuilderExtensions

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Examples

var validator = new ValidatorRuleBuilder<CreateUserRequest>()
    .NotEmpty(u => u.Name)
    .MaxLength(u => u.Name, 100)
    .EmailAddress(u => u.Email)
    .Range(u => u.Age, 18, 120)
    .Build();

Remarks

Rules use Expression<TDelegate> selectors so the property name can be inferred automatically for default error messages. The expression is compiled once at build time — acceptable because builders are configured at startup, not in hot loops.

Methods

Contains<T>(ValidatorRuleBuilder<T>, Expression<Func<T, string?>>, string, StringComparison, string?)

Validates that the selected string property contains value. The comparison is ordinal and case-sensitive by default. null fails this rule.

public static ValidatorRuleBuilder<T> Contains<T>(this ValidatorRuleBuilder<T> builder, Expression<Func<T, string?>> selector, string value, StringComparison comparison = StringComparison.Ordinal, string? errorMessage = null)

Parameters

builder ValidatorRuleBuilder<T>

selector Expression<Func<T, string>>

value string

comparison StringComparison

errorMessage string

Returns

ValidatorRuleBuilder<T>

Type Parameters

T

EmailAddress<T>(ValidatorRuleBuilder<T>, Expression<Func<T, string?>>, string?)

Validates that the selected string property is a valid email address. null fails this rule.

public static ValidatorRuleBuilder<T> EmailAddress<T>(this ValidatorRuleBuilder<T> builder, Expression<Func<T, string?>> selector, string? errorMessage = null)

Parameters

builder ValidatorRuleBuilder<T>

selector Expression<Func<T, string>>

errorMessage string

Returns

ValidatorRuleBuilder<T>

Type Parameters

T

EndsWith<T>(ValidatorRuleBuilder<T>, Expression<Func<T, string?>>, string, StringComparison, string?)

Validates that the selected string property ends with suffix. The comparison is ordinal and case-sensitive by default. null fails this rule.

public static ValidatorRuleBuilder<T> EndsWith<T>(this ValidatorRuleBuilder<T> builder, Expression<Func<T, string?>> selector, string suffix, StringComparison comparison = StringComparison.Ordinal, string? errorMessage = null)

Parameters

builder ValidatorRuleBuilder<T>

selector Expression<Func<T, string>>

suffix string

comparison StringComparison

errorMessage string

Returns

ValidatorRuleBuilder<T>

Type Parameters

T

GreaterThan<T, TNum>(ValidatorRuleBuilder<T>, Expression<Func<T, TNum>>, TNum, string?)

Validates that the selected comparable property is strictly greater than min. Works for int, long, double, decimal, and any IComparable<T>.

public static ValidatorRuleBuilder<T> GreaterThan<T, TNum>(this ValidatorRuleBuilder<T> builder, Expression<Func<T, TNum>> selector, TNum min, string? errorMessage = null) where TNum : IComparable<TNum>

Parameters

builder ValidatorRuleBuilder<T>

selector Expression<Func<T, TNum>>

min TNum

errorMessage string

Returns

ValidatorRuleBuilder<T>

Type Parameters

T

TNum

Length<T>(ValidatorRuleBuilder<T>, Expression<Func<T, string?>>, int, int, string?)

Validates that the selected string property length is between min and max characters (inclusive). null fails this rule.

public static ValidatorRuleBuilder<T> Length<T>(this ValidatorRuleBuilder<T> builder, Expression<Func<T, string?>> selector, int min, int max, string? errorMessage = null)

Parameters

builder ValidatorRuleBuilder<T>

selector Expression<Func<T, string>>

min int

max int

errorMessage string

Returns

ValidatorRuleBuilder<T>

Type Parameters

T

LessThan<T, TNum>(ValidatorRuleBuilder<T>, Expression<Func<T, TNum>>, TNum, string?)

Validates that the selected comparable property is strictly less than max. Works for int, long, double, decimal, and any IComparable<T>.

public static ValidatorRuleBuilder<T> LessThan<T, TNum>(this ValidatorRuleBuilder<T> builder, Expression<Func<T, TNum>> selector, TNum max, string? errorMessage = null) where TNum : IComparable<TNum>

Parameters

builder ValidatorRuleBuilder<T>

selector Expression<Func<T, TNum>>

max TNum

errorMessage string

Returns

ValidatorRuleBuilder<T>

Type Parameters

T

TNum

Matches<T>(ValidatorRuleBuilder<T>, Expression<Func<T, string?>>, string, string?)

Validates that the selected string property matches the given regular expression pattern. null fails this rule.

public static ValidatorRuleBuilder<T> Matches<T>(this ValidatorRuleBuilder<T> builder, Expression<Func<T, string?>> selector, string pattern, string? errorMessage = null)

Parameters

builder ValidatorRuleBuilder<T>

selector Expression<Func<T, string>>

pattern string

errorMessage string

Returns

ValidatorRuleBuilder<T>

Type Parameters

T

MaxCount<T, TItem>(ValidatorRuleBuilder<T>, Expression<Func<T, IEnumerable<TItem>?>>, int, string?)

Validates that the selected collection property has at most max items. null passes this rule — combine with NotEmpty<T, TItem>(ValidatorRuleBuilder<T>, Expression<Func<T, IEnumerable<TItem>?>>, string?) if null should be rejected.

public static ValidatorRuleBuilder<T> MaxCount<T, TItem>(this ValidatorRuleBuilder<T> builder, Expression<Func<T, IEnumerable<TItem>?>> selector, int max, string? errorMessage = null)

Parameters

builder ValidatorRuleBuilder<T>

selector Expression<Func<T, IEnumerable<TItem>>>

max int

errorMessage string

Returns

ValidatorRuleBuilder<T>

Type Parameters

T

TItem

MaxLength<T>(ValidatorRuleBuilder<T>, Expression<Func<T, string?>>, int, string?)

Validates that the selected string property does not exceed max characters. null passes this rule — combine with NotEmpty<T>(ValidatorRuleBuilder<T>, Expression<Func<T, string?>>, string?) if null should be rejected.

public static ValidatorRuleBuilder<T> MaxLength<T>(this ValidatorRuleBuilder<T> builder, Expression<Func<T, string?>> selector, int max, string? errorMessage = null)

Parameters

builder ValidatorRuleBuilder<T>

selector Expression<Func<T, string>>

max int

errorMessage string

Returns

ValidatorRuleBuilder<T>

Type Parameters

T

MinCount<T, TItem>(ValidatorRuleBuilder<T>, Expression<Func<T, IEnumerable<TItem>?>>, int, string?)

Validates that the selected collection property has at least min items. null fails this rule.

public static ValidatorRuleBuilder<T> MinCount<T, TItem>(this ValidatorRuleBuilder<T> builder, Expression<Func<T, IEnumerable<TItem>?>> selector, int min, string? errorMessage = null)

Parameters

builder ValidatorRuleBuilder<T>

selector Expression<Func<T, IEnumerable<TItem>>>

min int

errorMessage string

Returns

ValidatorRuleBuilder<T>

Type Parameters

T

TItem

MinLength<T>(ValidatorRuleBuilder<T>, Expression<Func<T, string?>>, int, string?)

Validates that the selected string property has at least min characters. null fails this rule.

public static ValidatorRuleBuilder<T> MinLength<T>(this ValidatorRuleBuilder<T> builder, Expression<Func<T, string?>> selector, int min, string? errorMessage = null)

Parameters

builder ValidatorRuleBuilder<T>

selector Expression<Func<T, string>>

min int

errorMessage string

Returns

ValidatorRuleBuilder<T>

Type Parameters

T

NonNegative<T, TNum>(ValidatorRuleBuilder<T>, Expression<Func<T, TNum>>, string?)

Validates that the selected comparable property is zero or positive (non-negative). Works for int, long, double, decimal, and any IComparable<T> whose zero value is default(TNum).

public static ValidatorRuleBuilder<T> NonNegative<T, TNum>(this ValidatorRuleBuilder<T> builder, Expression<Func<T, TNum>> selector, string? errorMessage = null) where TNum : struct, IComparable<TNum>

Parameters

builder ValidatorRuleBuilder<T>

selector Expression<Func<T, TNum>>

errorMessage string

Returns

ValidatorRuleBuilder<T>

Type Parameters

T

TNum

NotEmpty<T>(ValidatorRuleBuilder<T>, Expression<Func<T, string?>>, string?)

Validates that the selected string property is not null or empty ("").

public static ValidatorRuleBuilder<T> NotEmpty<T>(this ValidatorRuleBuilder<T> builder, Expression<Func<T, string?>> selector, string? errorMessage = null)

Parameters

builder ValidatorRuleBuilder<T>

selector Expression<Func<T, string>>

errorMessage string

Returns

ValidatorRuleBuilder<T>

Type Parameters

T

NotEmpty<T, TItem>(ValidatorRuleBuilder<T>, Expression<Func<T, IEnumerable<TItem>?>>, string?)

Validates that the selected collection property is not null or empty.

public static ValidatorRuleBuilder<T> NotEmpty<T, TItem>(this ValidatorRuleBuilder<T> builder, Expression<Func<T, IEnumerable<TItem>?>> selector, string? errorMessage = null)

Parameters

builder ValidatorRuleBuilder<T>

selector Expression<Func<T, IEnumerable<TItem>>>

errorMessage string

Returns

ValidatorRuleBuilder<T>

Type Parameters

T

TItem

NotNull<T, TProp>(ValidatorRuleBuilder<T>, Expression<Func<T, TProp?>>, string?)

Validates that the selected reference-type property is not null.

public static ValidatorRuleBuilder<T> NotNull<T, TProp>(this ValidatorRuleBuilder<T> builder, Expression<Func<T, TProp?>> selector, string? errorMessage = null) where TProp : class

Parameters

builder ValidatorRuleBuilder<T>

selector Expression<Func<T, TProp>>

errorMessage string

Returns

ValidatorRuleBuilder<T>

Type Parameters

T

TProp

NotWhiteSpace<T>(ValidatorRuleBuilder<T>, Expression<Func<T, string?>>, string?)

Validates that the selected string property is not null, empty, or whitespace.

public static ValidatorRuleBuilder<T> NotWhiteSpace<T>(this ValidatorRuleBuilder<T> builder, Expression<Func<T, string?>> selector, string? errorMessage = null)

Parameters

builder ValidatorRuleBuilder<T>

selector Expression<Func<T, string>>

errorMessage string

Returns

ValidatorRuleBuilder<T>

Type Parameters

T

Positive<T, TNum>(ValidatorRuleBuilder<T>, Expression<Func<T, TNum>>, string?)

Validates that the selected comparable property is strictly positive (greater than zero). Works for int, long, double, decimal, and any IComparable<T> whose zero value is default(TNum).

public static ValidatorRuleBuilder<T> Positive<T, TNum>(this ValidatorRuleBuilder<T> builder, Expression<Func<T, TNum>> selector, string? errorMessage = null) where TNum : struct, IComparable<TNum>

Parameters

builder ValidatorRuleBuilder<T>

selector Expression<Func<T, TNum>>

errorMessage string

Returns

ValidatorRuleBuilder<T>

Type Parameters

T

TNum

Range<T, TNum>(ValidatorRuleBuilder<T>, Expression<Func<T, TNum>>, TNum, TNum, string?)

Validates that the selected comparable property is between min and max (inclusive). Works for int, long, double, decimal, and any IComparable<T>.

public static ValidatorRuleBuilder<T> Range<T, TNum>(this ValidatorRuleBuilder<T> builder, Expression<Func<T, TNum>> selector, TNum min, TNum max, string? errorMessage = null) where TNum : IComparable<TNum>

Parameters

builder ValidatorRuleBuilder<T>

selector Expression<Func<T, TNum>>

min TNum

max TNum

errorMessage string

Returns

ValidatorRuleBuilder<T>

Type Parameters

T

TNum

StartsWith<T>(ValidatorRuleBuilder<T>, Expression<Func<T, string?>>, string, StringComparison, string?)

Validates that the selected string property starts with prefix. The comparison is ordinal and case-sensitive by default. null fails this rule.

public static ValidatorRuleBuilder<T> StartsWith<T>(this ValidatorRuleBuilder<T> builder, Expression<Func<T, string?>> selector, string prefix, StringComparison comparison = StringComparison.Ordinal, string? errorMessage = null)

Parameters

builder ValidatorRuleBuilder<T>

selector Expression<Func<T, string>>

prefix string

comparison StringComparison

errorMessage string

Returns

ValidatorRuleBuilder<T>

Type Parameters

T