支持列表属性的简单方法：
public static class UriBuilderExtensions
{
public static UriBuilder SetQuery<T>(this UriBuilder builder, T parameters)
{
var fragments = typeof(T).GetProperties()
.Where(property => property.CanRead)
.Select(property => new
{
property.Name,
Value = property.GetMethod.Invoke(parameters, null)
})
.Select(pair => new
{
pair.Name,
List = (!(pair.Value is string) && pair.Value is IEnumerable list ? list.Cast<object>() : new[] { pair.Value })
.Select(element => element?.ToString())
.Where(element => !string.IsNullOrEmpty(element))
})
.Where(pair => pair.List.Any())
.SelectMany(pair => pair.List.Select(value => Uri.EscapeDataString(pair.Name) + '=' + Uri.EscapeDataString(value)));
builder.Query = string.Join("&", fragments);
return builder;
}
}
一个更快的解决方案，就像拼出代码来序列化每种类型一样快：
public static class UriBuilderExtensions
{
public static UriBuilder SetQuery<TSource>(this UriBuilder builder, TSource parameters)
{
var fragments = Cache<TSource>.Properties
.Select(property => new
{
property.Name,
List = property.FetchValue(parameters)?.Where(item => !string.IsNullOrEmpty(item))
})
.Where(parameter => parameter.List?.Any() ?? false)
.SelectMany(pair => pair.List.Select(item => Uri.EscapeDataString(pair.Name) + '=' + Uri.EscapeDataString(item)));
builder.Query = string.Join("&", fragments);
return builder;
}
/// <summary>
/// Caches dynamically emitted code which converts a types getter property values to a list of strings.
/// </summary>
/// <typeparam name="TSource">The type of the object being serialized</typeparam>
private static class Cache<TSource>
{
public static readonly IEnumerable<IProperty> Properties =
typeof(TSource).GetProperties()
.Where(propertyInfo => propertyInfo.CanRead)
.Select(propertyInfo =>
{
var source = Expression.Parameter(typeof(TSource));
var getter = Expression.Property(source, propertyInfo);
var cast = Expression.Convert(getter, typeof(object));
var expression = Expression.Lambda<Func<TSource, object>>(cast, source).Compile();
return new Property
{
Name = propertyInfo.Name,
FetchValue = typeof(IEnumerable).IsAssignableFrom(propertyInfo.PropertyType) && propertyInfo.PropertyType != typeof(string) ?
CreateListFetcher(expression) :
CreateValueFetcher(expression)
};
})
.OrderBy(propery => propery.Name)
.ToArray();
/// <summary>
/// Creates a function which serializes a <see cref="IEnumerable"/> property value to a list of strings.
/// </summary>
/// <param name="get">A lambda function which retrieves the property value from a given source object.</param>
private static Func<TSource, IEnumerable<string>> CreateListFetcher(Func<TSource, object> get)
=> obj => ((IEnumerable)get(obj))?.Cast<object>().Select(item => item?.ToString());
/// <summary>
/// Creates a function which serializes a <see cref="object"/> property value to a list of strings.
/// </summary>
/// <param name="get">A lambda function which retrieves the property value from a given source object.</param>
private static Func<TSource, IEnumerable<string>> CreateValueFetcher(Func<TSource, object> get)
=> obj => new[] { get(obj)?.ToString() };
public interface IProperty
{
string Name { get; }
Func<TSource, IEnumerable<string>> FetchValue { get; }
}
private class Property : IProperty
{
public string Name { get; set; }
public Func<TSource, IEnumerable<string>> FetchValue { get; set; }
}
}
}
使用任一解决方案的示例：
var url = new UriBuilder("test.com").SetQuerySlow(new
{
Days = new[] { WeekDay.Tuesday, WeekDay.Wednesday },
Time = TimeSpan.FromHours(14.5),
Link = "conferences.com/apple/stream/15",
Pizzas = default(int?)
}).Uri;
输出：
http://test.com/Days=Tuesday&Days=Wednesday&Time=14:30:00&Link=conferences.com%2Fapple%2Fstream%2F15
这两种解决方案都不能处理奇异类型、索引参数或嵌套参数。
当手动序列化比较简单时，这种 c#7/.net4.7 方法可以提供帮助：
public static class QueryParameterExtensions
{
public static UriBuilder SetQuery(this UriBuilder builder, params (string Name, object Obj)[] parameters)
{
var list = parameters
.Select(parameter => new
{
parameter.Name,
Values = SerializeToList(parameter.Obj).Where(value => !string.IsNullOrEmpty(value))
})
.Where(parameter => parameter.Values.Any())
.SelectMany(parameter => parameter.Values.Select(item => Uri.EscapeDataString(parameter.Name) + '=' + Uri.EscapeDataString(item)));
builder.Query = string.Join("&", list);
return builder;
}
private static IEnumerable<string> SerializeToList(object obj)
{
switch (obj)
{
case string text:
yield return text;
break;
case IEnumerable list:
foreach (var item in list)
{
yield return SerializeToValue(item);
}
break;
default:
yield return SerializeToValue(obj);
break;
}
}
private static string SerializeToValue(object obj)
{
switch (obj)
{
case bool flag:
return flag ? "true" : null;
case byte number:
return number == default(byte) ? null : number.ToString();
case short number:
return number == default(short) ? null : number.ToString();
case ushort number:
return number == default(ushort) ? null : number.ToString();
case int number:
return number == default(int) ? null : number.ToString();
case uint number:
return number == default(uint) ? null : number.ToString();
case long number:
return number == default(long) ? null : number.ToString();
case ulong number:
return number == default(ulong) ? null : number.ToString();
case float number:
return number == default(float) ? null : number.ToString();
case double number:
return number == default(double) ? null : number.ToString();
case DateTime date:
return date == default(DateTime) ? null : date.ToString("s");
case TimeSpan span:
return span == default(TimeSpan) ? null : span.ToString();
case Guid guid:
return guid == default(Guid) ? null : guid.ToString();
default:
return obj?.ToString();
}
}
}
示例用法：
var uri = new UriBuilder("test.com")
.SetQuery(("days", standup.Days), ("time", standup.Time), ("link", standup.Link), ("pizzas", standup.Pizzas))
.Uri;
输出：
http://test.com/?days=Tuesday&days=Wednesday&time=14:30:00&link=conferences.com%2Fapple%2Fstream%2F15