C# Lambda 忽略大小写

Question

我想使用这个 LAMBDA 查询忽略大小写:

public IEnumerable<StationDto> StationSearch(string search)
        {
            var data = GenerateDtos();

            var list = data.Where(x => x.StationName.Contains(search));




            //var searchDto = new SearchDto {



            return null;
        }



        private static IEnumerable<StationDto> GenerateDtos()
        {
            return new List<StationDto>()
            {
                new StationDto()
                {
                    StationId = 1,
                    StationName = "DARTFORD"
                },
                new StationDto()
                {
                    StationId = 2,
                    StationName = "DARTMOUTH"
                },
                new StationDto()
                {
                    StationId = 3,
                    StationName = "TOWER HILL"
                },
                new StationDto()
                {
                    StationId = 4,
                    StationName = "DERBY"
                },
                new StationDto()
                {
                    StationId = 5,
                    StationName = "lIVERPOOL"
                },
                new StationDto()
                {
                    StationId = 6,
                    StationName = "LIVERPOOL LIME STREET"
                },
                new StationDto()
                {
                    StationId = 7,
                    StationName = "PADDINGTON"
                },
                new StationDto()
                {
                    StationId = 8,
                    StationName = "EUSTON"
                },
                new StationDto()
                {
                    StationId = 9,
                    StationName = "VICTORIA"
                },
            };
        }
    }

如果我搜索“DAR”，它会返回两个，但“dar”会返回 0 个项目。 我将如何修改此查询？

Answer 1

假设您正在谈论 x.StationName.Contains(search) 您可以这样做

var list = data
  .Where(x => x.StationName.IndexOf(search, StringComparison.OrdinalIgnoreCase) >= 0)

您还可以添加一个String 扩展方法

public static class StringExtensions
{
    public static bool Contains(this string thisObj, string value, StringComparer compareType) 
    {
        return thisObj.IndexOf(value, StringComparison.OrdinalIgnoreCase) >= 0;
    }
}

然后像这样使用它

 var list = data
   .Where(x => x.StationName.Contains(search, StringComparison.OrdinalIgnoreCase));