FluentValidation：使用来自其他属性的值自定义错误消息

Question

I have this:

 RuleForEach(inputData => inputData.Loads).ChildRules(inputData => {
        inputData.RuleFor(load => load.Asnow).GreaterThanOrEqualTo(0).WithMessage("no negative snow allowed"));
.... etc

Now I want to express in the message, which of the loads in the Loads collection the message is about.

"load" has a property "LoadName", the value of which i want to include in the message, something like

$"{load.LoadName} no negative snow allowed" 

How can I do that?

Answer 1

Use the WithMessage(Func<T, string>) overload:

RuleForEach(inputData => inputData.Loads)
    .ChildRules(inputData =>
    {
        inputData.RuleFor(load => load.Asnow).GreaterThanOrEqualTo(0).WithMessage(load => $"{load.LoadName} no negative snow allowed");
    });