[英]How can i make this linq query cleaner and more reusable?
我有一个 linq 查询,它返回几个环大小的计数。 然而,即使它在某种程度上可以重复使用,我也想看看我是否可以改进它。
private async Task<RingSizeLettersDto> CountOfLettersByRingFingerAsync(Func<RingSize, string> selector)
{
var ringSizes = await _ringSizeRepository.Get();
RingSizeLettersDto ringSizeLetters = new RingSizeLettersDto();
ringSizeLetters.G = ringSizes.Where(x => selector(x) == "G").Count();
ringSizeLetters.H = ringSizes.Where(x => selector(x) == "H").Count();
ringSizeLetters.I = ringSizes.Where(x => selector(x) == "I").Count();
ringSizeLetters.J = ringSizes.Where(x => selector(x) == "J").Count();
ringSizeLetters.K = ringSizes.Where(x => selector(x) == "K").Count();
ringSizeLetters.L = ringSizes.Where(x => selector(x) == "L").Count();
ringSizeLetters.M = ringSizes.Where(x => selector(x) == "M").Count();
ringSizeLetters.N = ringSizes.Where(x => selector(x) == "N").Count();
ringSizeLetters.O = ringSizes.Where(x => selector(x) == "O").Count();
ringSizeLetters.P = ringSizes.Where(x => selector(x) == "P").Count();
ringSizeLetters.Q = ringSizes.Where(x => selector(x) == "Q").Count();
ringSizeLetters.R = ringSizes.Where(x => selector(x) == "R").Count();
ringSizeLetters.S = ringSizes.Where(x => selector(x) == "S").Count();
ringSizeLetters.T = ringSizes.Where(x => selector(x) == "T").Count();
ringSizeLetters.U = ringSizes.Where(x => selector(x) == "U").Count();
ringSizeLetters.V = ringSizes.Where(x => selector(x) == "V").Count();
ringSizeLetters.W = ringSizes.Where(x => selector(x) == "W").Count();
ringSizeLetters.X = ringSizes.Where(x => selector(x) == "X").Count();
ringSizeLetters.Y = ringSizes.Where(x => selector(x) == "Y").Count();
ringSizeLetters.Z = ringSizes.Where(x => selector(x) == "Z").Count();
ringSizeLetters.Z1 = ringSizes.Where(x => selector(x) == "Z1").Count();
ringSizeLetters.Z2 = ringSizes.Where(x => selector(x) == "Z2").Count();
ringSizeLetters.Z3 = ringSizes.Where(x => selector(x) == "Z3").Count();
ringSizeLetters.Z4 = ringSizes.Where(x => selector(x) == "Z4").Count();
ringSizeLetters.Z5 = ringSizes.Where(x => selector(x) == "Z5").Count();
ringSizeLetters.Z6 = ringSizes.Where(x => selector(x) == "Z6").Count();
ringSizeLetters.NA = ringSizes.Where(x => selector(x) == "N/A").Count();
return ringSizeLetters;
}
我必须牢记改进:
您可以使用Count(x => selector(x) == "G")
,这将减少每行 1 个方法调用。
您可以创建一个Dictionary<string, int>
(可能char
as key 可能更准确),它表示按字符计数,然后在应用程序的其他地方,您可以使用要搜索的字符作为键来访问它:
var ringSizes = new[] { 1, 2, 2 };
var ringSizeLetters = ringSizes.GroupBy(x => Selector(x))
.ToDictionary(x => x.Key, v => v.Count());
var ocurrences = ringSizeLetters["A"];
根据您的特定用例是否允许这样做,更简洁的解决方案是使用字典。 从你的代码来看,最好的类型是IDictionary<string, int>
。 在这里,字符串键是标识符(例如 'Z1'),整数值是.Count()
的结果。
我在下面列出了一个可能的代码示例;
public static IDictionary<string, int> GetRingSizeLettersAsDict(
IEnumerable<string> sizeLetters,
IEnumerable<object> ringSizes)
{
IDictionary<string, int> ringSizeLetters = new();
sizeLetters.Select(
sl => ringSizeLetters.Add(
sl,
ringSizes.Where(rs => selector(rs).Equals(sl)).Count())
);
return ringSizeLetters;
}
这只是众多解决方案之一,但它应该与您的代码示例相同,前提是它适合您的用例。
这是一种伪代码,但这样的事情应该可以解决问题..
它是通过 System.Reflection 完成的
PropertyInfo[] properties = ringSizeLetters.GetProperties();
foreach (PropertyInfo property in properties)
{
var propertyName = property.Name;
var ringsizeValue = ringSizes.SingleOrDefault(x=> x.PROPERTYNAME == propertyName)
// if it finds ringsize Value
if(ringsizeValue != null)
{
property.SetValue(ringSizeLetters, ringsizeValue.Count());
}
}
如果您真的想要它们,您可以保留所有属性:
class RingSizeDto{
public int G { get; set;}
public int H { get; set;}
...并通过使用例如字典来支持它们来避免反射:
class RingSizeDto{
private Dictionary<string, int> _ringSizes = new();
public int G { get => _ringSizes[nameof(G)]; set _ringSizes[nameof(G)] = value; }
public int H { get => _ringSizes[nameof(H)]; set _ringSizes[nameof(H)] = value; }
...
这意味着可以通过提供字典一次性设置大小:
public RingSizeDto(Dictionary <string, int> sizes){
_ringSizes = sizes;
}
字典可以通过查询生成,例如
var sizes = someSizeList.GroupBy(s => s.SizeLetter).ToDictionary(g => g.Key, g => g.Count());
new RingSizeDto(sizes);
笔记; 如果您的列表没有所有可能的大小,您将希望通过使用 TryGetValue 来避免字典访问崩溃
public int G { get => _ringSizes.TryGetValue(nameof(G), out var x) ? x : 0; set _ringSizes[nameof(G)] = value; }
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