Philiprehberger.FluentGuard

Fluent parameter validation and guard clauses for .NET.

Installation

dotnet add package Philiprehberger.FluentGuard

Usage

using Philiprehberger.FluentGuard;

public class UserService
{
    public void CreateUser(string name, string email, int age)
    {
        Guard.Against(name, nameof(name)).NullOrWhiteSpace().ShorterThan(2).LongerThan(100);
        Guard.Against(email, nameof(email)).NullOrEmpty().InvalidEmail();
        Guard.Against(age, nameof(age)).Negative().Zero().OutOfRange(1, 150);

        // All parameters validated — proceed safely
    }
}

Null and default checks

var config = Guard.Against(config, nameof(config)).Null().Value;
Guard.Against(status, nameof(status)).Default();

Custom conditions

Guard.Against(orderId, nameof(orderId))
    .Condition(id => id.StartsWith("INVALID"), "Order ID has an invalid prefix.");

Collection checks

Guard.Against(items, nameof(items)).Empty();

Extracting the validated value

Every guard method returns the GuardClause<T> for chaining. Use the .Value property to retrieve the validated value:

string validName = Guard.Against(name, nameof(name)).NullOrWhiteSpace().Value;

API

Core (GuardClause<T>)

Method	Throws	Description
Null()	ArgumentNullException	Value is null
Default()	ArgumentException	Value equals default(T)
Negative()	ArgumentOutOfRangeException	Value is negative (requires IComparable<T>)
Zero()	ArgumentOutOfRangeException	Value is zero (requires IComparable<T>)
OutOfRange(min, max)	ArgumentOutOfRangeException	Value outside inclusive range
Condition(predicate, msg)	ArgumentException	Custom predicate returns true

String extensions

Method	Throws	Description
NullOrEmpty()	ArgumentNullException / ArgumentException	Null or empty string
NullOrWhiteSpace()	ArgumentNullException / ArgumentException	Null, empty, or white-space only
ShorterThan(min)	ArgumentException	Length below minimum
LongerThan(max)	ArgumentException	Length above maximum
InvalidEmail()	ArgumentException	Fails basic email regex
InvalidUri()	ArgumentException	Fails Uri.TryCreate

Collection extensions

Method	Throws	Description
Empty()	ArgumentNullException / ArgumentException	Null or has no elements

Development

dotnet build src/Philiprehberger.FluentGuard.csproj --configuration Release

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License

MIT