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你能控制TagBuilder类呈现属性的顺序吗?

tagbuilder asp.net c#

Glenn Slaven · 技术社区 · 14 年前

我知道这有点让人着迷,但是有没有一种方法可以控制 TagBuilder 类在调用时呈现HTML标记的属性 ToString() ?

也就是说

var tb = new TagBuilder("meta");            
tb.Attributes.Add("http-equiv", "Content-Type");            
tb.Attributes.Add("content", "text/html; charset=utf-8");    
tb.ToString(TagRenderMode.SelfClosing)

将返回

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />

不

<meta content="text/html; charset=utf-8" http-equiv="Content-Type" />

更改添加属性的顺序不会改变它,它似乎是按字母顺序呈现的。

3 回复 | 直到 6 年前

Daniel Dyson 14 年前

尝试使用这个类,它继承了TagBuilder并重写ToString方法,从属性构建一个SortedDictionary,并使用该字典进行呈现。

    public class MyTagBuilder : TagBuilder
    {
        //required to inherit from TagBuilder
        public MyTagBuilder(string tagName) : base(tagName){}

        //new hides the original ToString(TagRenderMode renderMode) 
        //The only changes in this method is that all calls to GetAttributesString
        //have been changed to GetMyAttributesString 
        public new string ToString(TagRenderMode renderMode)
        {
            switch (renderMode)
            {
                case TagRenderMode.StartTag:
                    return string.Format(CultureInfo.InvariantCulture, "<{0}{1}>", new object[] { this.TagName, this.GetMyAttributesString() });

                case TagRenderMode.EndTag:
                    return string.Format(CultureInfo.InvariantCulture, "</{0}>", new object[] { this.TagName });

                case TagRenderMode.SelfClosing:
                    return string.Format(CultureInfo.InvariantCulture, "<{0}{1} />", new object[] { this.TagName, this.GetMyAttributesString() });
            }
            return string.Format(CultureInfo.InvariantCulture, "<{0}{1}>{2}</{0}>", new object[] { this.TagName, this.GetMyAttributesString(), this.InnerHtml });
        }

        //Implement GetMyAttributesString where the Attributes are changed to a SortedDictionary
        private string GetMyAttributesString()
        {
            var builder = new StringBuilder();
            var myDictionary = new SortedDictionary<string, string>();     //new
            foreach (KeyValuePair<string, string> pair in this.Attributes) //new
            {                                                              //new
                myDictionary.Add(pair.Key, pair.Value);                    //new
            }                                                              //new 
            //foreach (KeyValuePair<string, string> pair in this.Attributes)
            foreach (KeyValuePair<string, string> pair in myDictionary)    //changed
            {
                string key = pair.Key;
                if (!string.Equals(key, "id", StringComparison.Ordinal) || !string.IsNullOrEmpty(pair.Value))
                {
                    string str2 = HttpUtility.HtmlAttributeEncode(pair.Value);
                    builder.AppendFormat(CultureInfo.InvariantCulture, " {0}=\"{1}\"", new object[] { key, str2 });
                }
            }
            return builder.ToString();
        }
    }

Carson63000 14 年前

我解体 TagBuilder.ToString() 使用Reflector,这是代码的关键部分:

foreach (KeyValuePair<string, string> pair in this.Attributes)
{
    string key = pair.Key;
    string str2 = HttpUtility.HtmlAttributeEncode(pair.Value);
    builder.AppendFormat(CultureInfo.InvariantCulture, " {0}=\"{1}\"", new object[] { key, str2 });
}

所以我会说不- this.Attributes 是一个 IDictionary<string,string> 根据msdn,当枚举“返回项的顺序未定义”时,接口。

magnus e 6 年前

我不想重写所有代码来修改排序行为,所以我改为使用反射将attributes属性更改为常规的未排序字典。

private class MyTagBuilder: TagBuilder
{
    private static readonly MethodInfo tagBuilderAttrSetMethod = typeof(TagBuilder).GetProperty(nameof(Attributes)).SetMethod;

    public MyTagBuilder(string tagName) : base(tagName)
    {
        // TagBuilder internally uses SortedDictionary, render attributes according to the order they are added instead
        tagBuilderAttrSetMethod.Invoke(this, new object[] { new Dictionary<string, string>() });
    }
}