为什么我在 FluentValidation MustAsync 中收到 CS1061 错误

Question

I'm trying to create some validation rules using static extension methods for IRuleBuilderOptions so I don't have to keep repeating myself when creating validators for Creating and Updating my objects.

For some reason I keep getting CS1061 errors for the country.Id in the MustAsync unique checks. I have tried replacing arrow functions with brackets and return , tried async / await . They all result in the same error. Intellisense shows that country is of type Country , and Id is a public property with both public getter and setter, so I'm not sure what I'm missing? I tried compiling in case it was just an Intellisense issue, but compilation fails with the same error.

Note: Using VS2022 / .Net6

public class Country
{
    public int Id { get; set; }
    public string Name { get; set; } = string.Empty;
    public string Code2 { get; set; } = string.Empty;
    public string Code3 { get; set; } = string.Empty;
    public int DisplayOrder { get; set; } = 1000;
    public bool Enabled { get; set; } = true;
}

public class CountryCreateValidator : AbstractValidator<Country>
{
    public CountryCreateValidator(IApplicationDbContext dbContext)
    {
        RuleFor(x => x.Name).Name(dbContext);
        RuleFor(x => x.Code2).Code2(dbContext);
        RuleFor(x => x.Code3).Code3(dbContext);
    }
}

public class CountryUpdateValidator : AbstractValidator<Country>
{
    public CountryUpdateValidator(IApplicationDbContext dbContext)
    {
        RuleFor(x => x.Id).NotEmpty();
        RuleFor(x => x.Name).Name(dbContext);
        RuleFor(x => x.Code2).Code2(dbContext);
        RuleFor(x => x.Code3).Code3(dbContext);
    }
}

public static class CountryRules
{
    public static IRuleBuilderOptions<Country, string> Name<Country>(this IRuleBuilder<Country, string> ruleBuilder, IApplicationDbContext dbContext) =>
        ruleBuilder.NotNull().NotEmpty().MaximumLength(64)
            .MustAsync((country, name, cancellationToken) =>
            {
                return dbContext.Countries.AllAsync(x => x.Id == country.Id /* error here */ || x.Name != name, cancellationToken);
            }).WithMessage(FvConstants.UNIQUE);

    public static IRuleBuilderOptions<Country, string> Code2<Country>(this IRuleBuilder<Country, string> ruleBuilder, IApplicationDbContext dbContext) =>
        ruleBuilder.NotEmpty().Length(2).Matches("^[A-Z]{2}$").WithMessage("{PropertyName} must be two uppercase letters")
            .MustAsync((country, code2, cancellationToken) =>
            {
                return dbContext.Countries.AllAsync(x => x.Id == country.Id || x.Code2 != code2, cancellationToken);
            }).WithMessage(FvConstants.UNIQUE);

    public static IRuleBuilderOptions<Country, string> Code3<Country>(this IRuleBuilder<Country, string> ruleBuilder, IApplicationDbContext dbContext) =>
        ruleBuilder.NotEmpty().Length(3).Matches("^[A-Z]{3}$").WithMessage("{PropertyName} must be three uppercase letters")
            .MustAsync((country, code3, cancellationToken) =>
            {
                return dbContext.Countries.AllAsync(x => x.Id == country.Id || x.Code3 != code3, cancellationToken);
            }).WithMessage(FvConstants.UNIQUE);
}

public class FvConstants
{
    public const string UNIQUE = "{PropertyName} must be unique";
}

Here is a screenshot showing proper typeing of the country parameter and the error I am getting...

Answer 1

Because Country is the name of generic parameter of your methods, not a type name. Just remove <Country> from the signatures:

public static IRuleBuilderOptions<Country, string> Name(...
public static IRuleBuilderOptions<Country, string> Code2(...
public static IRuleBuilderOptions<Country, string> Code3(...