将值追加到现有 IEnumerable 的末尾时产生回报
本文关键字:回报 IEnumerable 追加 | 更新日期: 2023-09-27 18:30:39
我刚刚发现了yield return
,我看起来真的很好。我以这样的方法使用它:
public IEnumerable<ValidationResult> Validate(ValidationContext vc)
{
if (Name == "Arbitary")
yield return new ValidationResult("Bad Name.", new[] { "Name" });
else if (Email == "BadEmail")
yield return new ValidationResult("Bad Email.", new [] {"Email" });
// further rules follow.
}
但是,我需要更改此方法以从子方法返回一些验证结果。如果不使用yield
,代码将如下所示:
public override IEnumerable<ValidationResult> Validate(ValidationContext vc)
{
// TryValidateObject fills the ICollection you pass it.
List<ValidationResult> retVal = new List<ValidationResult>();
Validator.TryValidateObject(this, vc, retVal, true);
if (Name == "Arbitary")
retVal.Add(new ValidationResult("Bad Name.", new[] { "Name" }));
else if (Email == "BadEmail")
retVal.Add(new ValidationResult("Bad Email.", new[] { "Email" }));
return retVal;
}
是否可以使用 yield
重写?
你在找这个吗?
public override IEnumerable<ValidationResult> Validate(ValidationContext vc)
{
// TryValidateObject fills the ICollection you pass it.
List<ValidationResult> retVal = new List<ValidationResult>();
Validator.TryValidateObject(this, vc, retVal, true);
foreach (var item in retVal)
yield return item;
if (Name == "Arbitary")
yield return new ValidationResult("Bad Name.", new[] { "Name" });
else if (Email == "BadEmail")
yield return new ValidationResult("Bad Email.", new[] { "Email" });
}
如果是这样,我相信第一个版本看起来更好。
到目前为止发布的其他解决方案都很好。这是解决问题的另一种方法:
- 创建两个序列
- 将它们连接起来
- 返回串联。
所以:
public override IEnumerable<ValidationResult> Validate(ValidationContext vc)
{
return ResultsFromValidator(vc).Concat(AdditionalResults());
}
private IEnumerable<ValidationResult> ResultsFromValidator(ValidationContext vc)
{
List<ValidationResult> retVal = new List<ValidationResult>();
Validator.TryValidateObject(this, vc, retVal, true);
return retVal;
}
private IEnumerable<ValidationResult> AdditionalResults()
{
if (Name == "Arbitrary")
yield return new ValidationResult("Bad Name.", new[] { "Name" });
...
}
当然。只需使用这个:
foreach (var item in retVal) {
yield return item;
}
之后,您还可以继续收益回报。因此,您可以在调用该方法后返回 retVal,然后像第一个示例一样继续。喜欢这个:
public override IEnumerable<ValidationResult> Validate(ValidationContext vc)
{
List<ValidationResult> retVal = new List<ValidationResult>();
Validator.TryValidateObject(this, vc, retVal, true);
foreach (var item in retVal) {
yield return item;
}
if (Name == "Arbitary")
yield return new ValidationResult("Bad Name.", new[] { "Name" });
else if (Email == "BadEmail")
yield return new ValidationResult("Bad Email.", new[] { "Email" });
//...
}