c# - Concatenating IEnumerable> values into string using Linq

Question

Given IEnumerable<KeyValuePair<string,string>>, I'm trying to use linq to concatenate the values into one string.

My Attempt:

string path = attributes.Aggregate((current, next) => "@" + current.Key + "=" + current.Value + " and @" + next.Key + "=" + next.Value);

This produces the error:

Cannot convert expression type 'string' to return type 'KeyValuePair<string,string>'

Is there a more effiecient way to do this in linq?

The full method...

public IEnumerable<XmlNode> GetNodes(IEnumerable<KeyValuePair<string,string>> attributes) {
    StateInfoXmlDocument stateInfoXmlDocument = new StateInfoXmlDocument();
    string path = attributes.Aggregate((current, next) => "@" + current.Key + "=" + current.Value + " and @" + next.Key + "=" + next.Value);
    string schoolTypeXmlPath = string.Format(SCHOOL_TYPE_XML_PATH, path);

    return stateInfoXmlDocument.SelectNodes(schoolTypeXmlPath).Cast<XmlNode>().Distinct();
}

Answer 1

这是你要找的吗？

var strings = attributes.Select(kvp => string.Format("@{0}={1}", kvp.Key, kvp.Value));
string path = string.Join(" and ", strings);

Answer 2

string s = String.Join("@",attributes.Select(kv=>kv.Key+"="+kv.Value));

Answer 3

如果你想使用聚合来创建一个字符串，如果你使用非种子版本，则需要使用聚合的种子重载，那么调用中的所有类型都必须相同。

Answer 4

string templ = "{0}={1}";
string _authStr = String.Join("&", formParams.Select(kv => String.Format(templ, kv.Key, kv.Value));