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using System;
using System.Collections.Generic;
using System.Reflection;
namespace Apewer.Source
{
/// <summary>索引。</summary>
[Serializable]
[AttributeUsage(AttributeTargets.Property, AllowMultiple = true, Inherited = true)]
public sealed class IndexAttribute : Attribute, IToJson
{
PropertyInfo _property = null;
ColumnAttribute _column;
string _name = null;
FieldOrder _order = FieldOrder.Ascend;
/// <summary>索引名称。</summary>
public string Name { get => _name; }
/// <summary>排序。</summary>
public FieldOrder Order { get => _order; set => _order = value; }
/// <summary>列。</summary>
public ColumnAttribute Column { get => _column; }
/// <summary>属性。</summary>
public PropertyInfo Property { get => _property; }
/// <summary>表示此属性是索引的一部分。</summary>
/// <param name="name">索引名称。</param>
public IndexAttribute(string name)
{
if (string.IsNullOrEmpty(name)) throw new ArgumentNullException(nameof(name));
_name = name;
}
internal void SetColumn(ColumnAttribute column)
{
_column = column;
}
/// <summary>解析列的索引。</summary>
/// <remarks>注意:此方法不再抛出异常,当不存在正确的列特性时将返回 NULL 值</remarks>
public static IndexAttribute[] Parse(PropertyInfo property)
{
if (property == null) return null;
var attributes = property.GetCustomAttributes(typeof(IndexAttribute), true);
var ias = new List<IndexAttribute>();
foreach (var attribute in attributes)
{
var ia = attribute as IndexAttribute;
if (ia == null) continue;
if (ia._name.IsEmpty()) continue;
ia._property = property;
ias.Add(ia);
}
return ias.ToArray();
}
/// <summary>生成 Json 对象。</summary>
/// <exception cref="NotImplementedException"></exception>
public Json ToJson()
{
var json = Json.NewObject();
json.SetProperty("name", _name);
json.SetProperty("order", _order.ToString());
if (_column != null) json.SetProperty("column", _column.ToJson());
return json;
}
/// <summary></summary>
public override string ToString() => $"Index = {_name}, Field = {_column?.Field}, Order = {_order}";
}
}