Contracts

Contracts library

Provide classes for validating various conditions and values that are originated from arguments or state.

Related Packages

• DevGuild.AspNetCore.Contracts

Description

This package allows performing less cumbersome checks of the various values when failure should be followed by a thrown exception. Instead of performing manual checks and throwing exception, this package allows to perform the check with a single method call that will throw an exception if the check fails.

Two origins of the value are currently supported: a method argument and a state.

When using argument-related checks, the type of exception thrown is either ArgumentException or ArgumentNullException with the argument name included.

State-related checks are more generic and should probably be suitable for most non-argument checks. When such check is failed the InvalidOperationException is thrown.

All methods used for performing the checks have aggressive inlining turned on so there should be no performance impact in comparison with manual if-throw check.

Example usage

Validating arguments manually:

public Permission(Guid id, [NotNull]String name, Int32 bits)
{
    if (name == null)
    {
        throw new ArgumentNullException(nameof(name));
    }

    if (bits <= 0)
    {
        throw new ArgumentException("name must be greater than 0");
    }

    this.Id = id;
    this.Name = name;
    this.Bits = bits;
}

Validating arguments using this package:

public Permission(Guid id, [NotNull]String name, Int32 bits)
{
    Ensure.Argument.NotNull(name, nameof(name));
    Ensure.Argument.GreaterThan(bits, 0, nameof(bits));

    this.Id = id;
    this.Name = name;
    this.Bits = bits;
}

Validating state manually:

public ImageUploadConfiguration BuildConfiguration()
{
    if (String.IsNullOrEmpty(this.containerName) || this.containerPrefix == null)
    {
        throw new InvalidOperationException("Container is not configured");
    }

    if (this.allowedFormats.Count == 0)
    {
        throw new InvalidOperationException("No image format was allowed");
    }

    if (this.variations.Count == 0)
    {
        throw new InvalidOperationException("No variation was defined");
    }

    return new ImageUploadConfiguration(this.identifier, this.version, this.containerName, this.containerPrefix, this.allowedFormats, this.variations);
}

Validating state using this package:

public ImageUploadConfiguration BuildConfiguration()
{
    Ensure.State.NotNullOrEmpty(this.containerName, "Container is not configured");
    Ensure.State.NotNull(this.containerPrefix, "Container is not configured");
    Ensure.State.HasElements(this.allowedFormats, "No image format was allowed");
    Ensure.State.HasElements(this.variations, "No variation was defined");

    return new ImageUploadConfiguration(this.identifier, this.version, this.containerName, this.containerPrefix, this.allowedFormats, this.variations);
}

Supported validations

Name	Description	Argument	State
NotNull	Checks if value is not null	+	+
Null	Checks if value is null	+	+
HasValue	Checks if nullable value has a value	+	+
DoesNotHaveValue	Checks if nullable value does not have a value	+	+
MeetCondition	Checks if a custom condition is met	+	+
DoesNotMeetCondition	Checks if a custom condition is not met	+	+
EqualTo	Checks if value is equal to specific value	+	+
NotEqualTo	Checks if value is not equal to specific value	+	+
GreaterThan	Checks if value is greater than specific value	+	+
GreaterThanOrEqualTo	Checks if value is greater than or equal to specific value	+	+
LessThan	Checks if value is less than specific value	+	+
LessThanOrEqualTo	Checks if value is less than or equal to specific value	+	+
NotEmpty	Checks if string value is not equal to empty string	+	+
Empty	Checks if string value is equal to empty string	+	+
NotNullOrEmpty	Checks if string value is not null or equal to empty string	+	+
NullOrEmpty	Checks if string value is null or equal to empty string	+	+
HasNoElements	Checks if collection value is empty	+	+
HasElements	Checks if collection value is not empty	+	+
HasSingleElement	Checks if collection value has a single element	+	+
HasExactNumberOfElements	Checks if collection value has a specific number of elements	+	+
IsConvertible.ToGuid	Checks if value could be converted to Guid type	+