字典排序列表

本文关键字：列表 排序 字典 | 更新日期: 2023-09-27 18:00:28

我有一个需要排序的字典值集合（List<>）。基本上，每个字典都是一个"行"，集合是一页行。一个简单的例子；

       var data = new List<Dictionary<string,string>>();
       data.Add(new Dictionary<string,string>() {
                    { "Firstname", "Bob"},
                    { "Lastname", "Banana"}
       });
       data.Add(new Dictionary<string, string>() {
                    { "Firstname", "Amy"},
                    { "Lastname", "Apple"}
       });
       data.Add(new Dictionary<string, string>() {
                    { "Firstname", "Charlie"},
                    { "Lastname", "Coconut"}
       });
       data.Add(new Dictionary<string, string>() {
                    { "Firstname", "Andy"},
                    { "Lastname", "Apple"}
       });

生成的排序字符串类似于"SQL"，例如

 Lastname asc, Firstname desc

我已经在数据对象上尝试过.OrderBy()，但它似乎对KeyValuePairs不起作用。

我想知道如何使用动态排序语句将数据列表按此顺序排序：

 Apple, Andy
 Apple, Amy
 Banana, Bob
 Coconut, Charlie

如果一些花哨的LINQ可以工作，请使用.NET 4.0。谢谢你的建议。

字典排序列表

data.OrderBy(dict => dict["Lastname"])
    .ThenByDescending(dict => dict["Firstname"])

如果是动态的：

var sorted = data.OrderBy(item => 1); // identity (stable) sort
orderby = "Lastname asc, Firstname desc";
foreach (var key in orderby.Split(',').Select(clause => clause.Trim()))
{
    if (key.EndsWith(" desc", StringComparison.CurrentCultureIgnoreCase))
    {
        key = key.Substr(0, key.Length - 5);
        sorted = data.ThenByDescending(dict => dict[key]);
    } else
    {
        if (key.EndsWith(" asc", StringComparison.CurrentCultureIgnoreCase)) 
        {
            key = key.Substr(0, key.Length - 4);
        }
        sorted = data.ThenBy(dict => dict[key]);
    }
}

  private static IEnumerable<Dictionary<string, string>> Sort(IEnumerable<Dictionary<string,string>> data, string orderByString)
  {
     var orderBy =
        orderByString.Split(',').Select(
           s => s.Split(new[] {' '}, StringSplitOptions.RemoveEmptyEntries))
           .Select (a => new {Field=a[0],Descending = "desc".Equals (a[1], StringComparison.InvariantCultureIgnoreCase)})
           .ToList ();
     if (orderBy.Count == 0)
        return data;
     // First one is OrderBy or OrderByDescending.
     IOrderedEnumerable<Dictionary<string, string>> ordered =
        orderBy[0].Descending ? data.OrderByDescending (d => d[orderBy[0].Field]) : data.OrderBy (d => d[orderBy[0].Field]);
     for (int i = 1; i < orderBy.Count; i++)
     {
        // Rest are ThenBy or ThenByDescending.
        var orderClause = orderBy[i];
        ordered =
           orderBy[i].Descending ? ordered.ThenByDescending(d => d[orderClause.Field]) : ordered.ThenBy(d => d[orderClause.Field]);
     }
     return ordered;
  }

我不确定你这里是否有最好的实现，但由于上面是一个例子，而不是真实世界的情况，所以你可以这样做：

data
.OrderBy(x => x["Lastname"])
.ThenByDescending(x => x["Firstname"])
.Select(x => 
    new 
    { 
        Lastname = x["Lastname"],
        Firstname = x["Firstname"],
    });

除非有特定的原因需要使用Dictionaries，否则使用类似的东西会更好；

public class Person
{
    public string FirstName {get; set;}
    public string LastName  {get; set;}
}
var people = new [] {
    new Person { FirstName = "Amy", LastName = "Apple" },
    new Person { FirstName = "Andy", LastName = "Apple" },
    new Person { FirstName = "Charlie", LastName = "Coconut" } 
};
var sortedPeople = people
    .OrderBy(f => f.LastName)
    .ThenByDescending(f => f.FirstName);

根据评论更新

请参阅这篇文章，了解可能的解决方案；

实体框架4.1 object.properties=value 的简单动态表达式

和

具有多个/未知条件的动态linq查询

（以上内容现已全面实施如下）

public static int UpdateSegment(int segmentId)
{
    Table<ContactViewItem> Contacts;
    var  conditionsFormatted = new Dictionary<string, string>();
    //Retrieve all conditions
    var segmentConditions = Lists.GetSegmentConditions(segmentId);
    //Iterate through conditions and process them
    foreach (var condition in segmentConditions)
    {
        switch (condition.Operator)
        {
            case SegmentCondition.OperatorType.Equals:
                condition.Condition =  string.Format("{1}='"{0}'"", condition.Criteria, condition.Field);
                break;
            case SegmentCondition.OperatorType.Contains:
                condition.Condition = string.Format("{1}.Contains('"{0}'")", condition.Criteria, condition.Field);
                break;
            default:
                throw new ApplicationException("Unexpected Operator for Condition");
        }
    }

    var db = new DbContext(ConfigurationManager.ConnectionStrings["c"].ConnectionString);
    var statusConditions = "Status = 1";
    var results = (IQueryable)db.Contacts.Where(statusConditions);
    var distinctFields = (from c in segmentConditions select c.Field).Distinct();
    foreach (var distinctField in distinctFields)
    {
        var values = (from s in segmentConditions where s.Field == distinctField select s.Condition).ToArray();
        var valuesJoined = string.Join("||", values);
        results = results.Where(valuesJoined);
    }
    results = results.Select("id");

    var xml = new StringBuilder();
    xml.Append("<Ids>");
    foreach (var id in results)
    {
        xml.Append(String.Format("<Id>{0}</Id>", id));
    }
    xml.Append("</Ids>");
    var idXml = XDocument.Parse(xml.ToString());
    return Lists.UpdateSegmentContacts(idXml.ToString(), segmentId);
}

也许会有帮助，也许不会！

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