Rule Predicates

Built-in factory methods for common validation patterns. No raw expressions needed.

using RoslynRules.Predicates;

Available Predicates

All methods are static and return a Rule. Every method accepts an optional trailing string? description = null argument (omitted below for brevity). The path argument is a parameter name and may be a dotted member-access path (e.g. "order.CustomerId").

Null / Empty Checks

Predicate	Description
`IsNotNull(path)`	Value is not null
`IsNotNullOrEmpty(path)`	String is not null or empty
`IsNotNullOrWhiteSpace(path)`	String is not null or whitespace
`IsNotEmpty(path)`	Collection has any elements (`.Any()`)
`IsEmpty(path)`	Collection has no elements (`!.Any()`)

Comparison

Predicate	Description
`GreaterThan<T>(path, value)`	`>` comparison (`T : struct`)
`GreaterThanOrEqual<T>(path, value)`	`>=` comparison (`T : struct`)
`LessThan<T>(path, value)`	`<` comparison (`T : struct`)
`LessThanOrEqual<T>(path, value)`	`<=` comparison (`T : struct`)
`Equals<T>(path, value)`	`==` comparison
`NotEquals<T>(path, value)`	`!=` comparison
`InRange<T>(path, min, max)`	Inclusive range check (`T : struct`)
`NotInRange<T>(path, min, max)`	Outside exclusive range (`T : struct`)

String

Predicate	Description
`MatchesRegex(path, pattern)`	Regex match
`Contains(path, value)`	String contains substring
`StartsWith(path, value)`	String prefix
`EndsWith(path, value)`	String suffix
`HasLength(path, length)`	String has exact length
`HasMinLength(path, minLength)`	String length `>=` minLength
`HasMaxLength(path, maxLength)`	String length `<=` maxLength

Collection

Predicate	Description
`CountEquals(path, count)`	Collection count `==` count
`CountGreaterThan(path, count)`	Collection count `>` count
`CountLessThan(path, count)`	Collection count `<` count
`Contains<T>(path, value)`	Collection contains element

Boolean / Type

Predicate	Description
`IsTrue(path)`	Boolean is true
`IsFalse(path)`	Boolean is false
`IsOfType<T>(path)`	Value is of type `T`

Usage

var workflow = new Workflow
{
    Rules =
    {
        RulePredicates.IsNotNull("customer"),
        RulePredicates.GreaterThan("customer.Age", 18),
        RulePredicates.MatchesRegex("customer.Email", @"^[^@]+@[^@]+\.[^@]+$"),
        RulePredicates.InRange("customer.Score", 0, 100),
        RulePredicates.HasMinLength("customer.Name", 2)
    }
};

Custom Predicates

Create your own by instantiating Rule with the appropriate Expression:

public static Rule HasMinimumOrders(string path, int min)
{
    return new Rule
    {
        Description = $"{path} has at least {min} orders",
        Expression = $"{path}.Orders.Count >= {min}"
    };
}

Rule — Underlying model