Question

我正在使用XMLWriter来创建聊天xml。应通过将收到的消息附加到现有聊天文件来更新此文件。例如，在下面的xml文件中，我想在msg_id = 5的节点之后追加一个新的消息节点我的问题是我得到的代码创建了一个新的XMl文件。请指教。

我的XML文件

<?xml version="1.0" encoding="utf-8"?>
<client>
    <name>client_name</name>
    <url>client_name.myapp.com</url>
    <ver>1</ver>
    <conversation>
        <sender_id>5</sender_id>
        <fname>First</fname>
        <mname>Middle</mname>
        <lname>Last</lname>
        <last_seen>l, d-M-y H:i:s T</last_seen>
        <messages>
            <message>
                <msg_id>1</msg_id>
                <recepient_id />
                <message>Lorem ipsum dolor sit amet, consectetuer adipiscing elit.</message>
            </message>
            <message>
                <msg_id>2</msg_id>
                <recepient_id />
                <message>Lorem ipsum dolor sit amet, consectetuer adipiscing elit.</message>
            </message>
            <message>
                <msg_id>3</msg_id>
                <recepient_id />
                <message>Lorem ipsum dolor sit amet, consectetuer adipiscing elit.</message>
            </message>
            <message>
                <msg_id>4</msg_id>
                <recepient_id />
                <message>Lorem ipsum dolor sit amet, consectetuer adipiscing elit.</message>
            </message>
            <message>
                <msg_id>5</msg_id>
                <recepient_id />
                <message>Lorem ipsum dolor sit amet, consectetuer adipiscing elit.</message>
            </message>
        </messages>
    </conversation>
</client>

我的代码

chat = JsonConvert.DeserializeObject<Chat>(json_data);

            for (int conversations_count = 0; conversations_count < chat.conversations.Count; conversations_count++) // Loop through List with for
            {
                var conversation = chat.conversations[conversations_count];
                var conversation_file_name = conversation.fname + " " + conversation.mname + " " + conversation.lname;
                var messages = conversation.messages;
                if (File.Exists(conversation_file_name))
                {

                using (XmlWriter writer = XmlWriter.Create(conversation_file_name+".xml"))
                    {
                        writer.WriteStartDocument();
                        writer.WriteStartElement("client");
                        writer.WriteElementString("name", "client_name");
                        writer.WriteElementString("url", "client_name.myapp.com");
                        writer.WriteElementString("ver", "1.0");
                        writer.WriteStartElement("conversation");
                        writer.WriteElementString("sender_id", conversation.sender_id.ToString());
                        writer.WriteElementString("fname", conversation.fname.ToString());
                        writer.WriteElementString("mname", conversation.mname.ToString());
                        writer.WriteElementString("lname", conversation.lname.ToString());
                        writer.WriteElementString("last_seen", conversation.last_seen.ToString());
                        writer.WriteStartElement("messages");
                        for (int messages_count = 0; messages_count < messages.Count; messages_count++) // Loop through List with for
                        {
                            writer.WriteStartElement("message");

                            writer.WriteElementString("msg_id", messages[messages_count].msg_id.ToString());                           
                            writer.WriteElementString("recepient_id", messages[messages_count].recepient_id.ToString());
                            writer.WriteElementString("message", messages[messages_count].message.ToString());

                            writer.WriteEndElement();
                        }
                        writer.WriteEndElement();
                        writer.WriteEndElement();
                        writer.WriteEndElement();
                        writer.WriteEndDocument();
                    }

                }               
            }

Answer 1

我建议使用更简单的XML API，例如，使用XmlDocument：

var doc = new XmlDocument();
doc.Load(conversation_file_name);
var messagesNode = doc.DocumentElement
                      .SelectSingleNode("/client/conversation/messages");
var lastMessageId = messagesNode.SelectSingleNode("./message[last()]/msg_id");
var id = lastMessageId != null ? int.Parse(lastMessageId.InnerText.Trim()) : 0;

for (int messages_count = 0; messages_count < messages.Count; messages_count++) // Loop through List with for
{
    //create nodes to be added to existing XML
    var newMessage = doc.CreateElement("message");
    var newId = doc.CreateElement("msg_id");
    var newRecepient = doc.CreateElement("recepient_id");
    var newMessageContent = doc.CreateElement("message");

    //set new nodes content
    newId.InnerText = messages[messages_count].msg_id.ToString();
    newRecepient.InnerText = messages[messages_count].recepient_id.ToString();
    newMessageContent.InnerText = messages[messages_count].message.ToString();

    //append each node to desired parent node
    newMessage.AppendChild(newId);
    newMessage.AppendChild(newRecepient);
    newMessage.AppendChild(newMessageContent);
    messagesNode.AppendChild(newMessage);
}

doc.Save(conversation_file_name);

C＃将节点附加到现有的xml文件

1 个答案: