Record Equality Source Generator

This is a sample where I use an attribute to modify a records default equality operator using an Equality attribute and the use of the partial keyword.

Reasoning

Records use value equality, but often domain entities have identifiers that denote the identity of a record, and that's what we want to compare. Other values on the entity might be different, but logically they may be the same entity.

Use Case

The common use case is we want to look at an Id property. You'd use the source generator

public partial record CartItem(
    [Equality] int Id,
    string Name = "",
    decimal Price = 0m);

Now when you compare two CartItem instances, they will compare based on the value of Id alone. You may also add the equality attribute on multiple properties for composite keys.

public partial record CartItem(
    [Equality] int Id,
    [Equality] string Name = "",
    decimal Price = 0m);

Possible Improvements

If you're interested in using this in your project, some other improvements might include:

• Supporting Comparison types like Oridinal or Ignore Case on properties that support such comparers i.e. string.
• Overriding the EqualityContract to support inheritance comparison properly.

License

The MIT License (MIT) Copyright © 2022 Khalid Abuhakmeh

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.