by ardalis

ardalis / GuardClauses

A simple package with guard clause extensions.

598 Stars 87 Forks Last release: 3 months ago (2.0.0) MIT License 119 Commits 17 Releases

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Guard Clauses

A simple package with guard clause extensions.

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    public void ProcessOrder(Order order)
        Guard.Against.Null(order, nameof(order));

    // process order here

// OR

public class Order
    private string _name;
    private int _quantity;
    private long _max;
    private decimal _unitPrice;
    private DateTime _dateCreated;

    public Order(string name, int quantity, long max, decimal unitPrice, DateTime dateCreated)
        _name = Guard.Against.NullOrWhiteSpace(name, nameof(name));
        _quantity = Guard.Against.NegativeOrZero(quantity, nameof(quantity));
        _max = Guard.Against.Zero(max, nameof(max));
        _unitPrice = Guard.Against.Negative(unitPrice, nameof(unitPrice));
        _dateCreated = Guard.Against.OutOfSQLDateRange(dateCreated, nameof(dateCreated));

Supported Guard Clauses

  • Guard.Against.Null (throws if input is null)
  • Guard.Against.NullOrEmpty (throws if string, guid or array input is null or empty)
  • Guard.Against.NullOrWhiteSpace (throws if string input is null, empty or whitespace)
  • Guard.Against.OutOfRange (throws if integer/DateTime/enum input is outside a provided range)
  • Guard.Against.OutOfSQLDateRange (throws if DateTime input is outside the valid range of SQL Server DateTime values)
  • Guard.Against.Zero (throws if number input is zero)

Extending with your own Guard Clauses

To extend your own guards, you can do the following:

    // Using the same namespace will make sure your code picks up your 
    // extensions no matter where they are in your codebase.
    namespace Ardalis.GuardClauses
        public static class FooGuard
            public static void Foo(this IGuardClause guardClause, string input, string parameterName)
                if (input?.ToLower() == "foo")
                    throw new ArgumentException("Should not have been foo!", parameterName);

// Usage
public void SomeMethod(string something)
    Guard.Against.Foo(something, nameof(something));


Build Notes

  • Remember to update the PackageVersion in the csproj file and then a build on master should automatically publish the new package to
  • Add a release with form
    to GitHub Releases in order for the package to actually be published to Nuget. Otherwise it will claim to have been successful but is lying to you.

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