cratis-fundamentals-concept

Cratis domain concepts and event-source identities

Replace a primitive only when the domain gives it distinct meaning. Keep value concepts and Chronicle stream identities separate.

Verified product sources

Sources:

Package	Purpose
Cratis.Fundamentals	ConceptAs<T>, IGeneratable<TSelf>, IGeneratableInContext<TSelf>, GenerationContext and GenerateValue
Cratis.Chronicle	Cratis.Chronicle.Events.EventSourceId and EventSourceId<T>
@cratis/fundamentals	TypeScript ConceptAs<T>, field, Guid, and JSON conversion

Reverify product sources before claiming support for another version.

Choose the type

• Derive a name, amount, code, number, or non-stream entity ID from ConceptAs<T>.
• Derive an identity from EventSourceId<T> only when that value is actually passed to Chronicle as the event-source/stream ID.
• Do not use ConceptAs<Guid> for a Chronicle stream identity.
• Do not use EventSourceId<T> merely because a value is called an ID.
• Do not wrap an enum. An enum already expresses a closed domain concept.
• Keep DTO-only transport values primitive unless the domain type belongs in the public contract.

Both generic bases require an underlying type that implements IComparable.

Create a value concept

A value concept contains exactly one wrapped value. Do not add extra properties; Fundamentals converters assume the concept is a single-value type and additional state can be lost during serialization.

// Copyright (c) Cratis. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

using Cratis.Concepts;

namespace <NamespaceRoot>.<Feature>;

/// <summary>
/// Represents the <description>.
/// </summary>
/// <param name="Value">The underlying value.</param>
public record <ConceptName>(<ComparableUnderlyingType> Value) :
    ConceptAs<<ComparableUnderlyingType>>(Value);

ConceptAs<T> supplies implicit conversion from the concept to T. Add the reverse conversion only when it improves the domain API: