稽查目標 PTT 用戶的留言，使用 AngleSharp + pttweb

PttMessageCrawler.linq

async Task Main()
{
    var pttUser = "";
    var page = 1;
    
    var crawlar = new PttMessageCrawler();
    var result = await crawlar.GetMessages(pttUser, page);
    
    result.Dump();
}

/// <summary>
/// 爬蟲服務
/// </summary>
public class PttMessageCrawler
{
    private readonly IBrowsingContext _browser;

    /// <summary>
    /// 初始化
    /// </summary>
    public PttMessageCrawler()
    {
        var config = Configuration.Default.WithDefaultLoader();
        var browser = BrowsingContext.New(config);
        this._browser = browser;
    }

    /// <summary>
    /// 取得留言內容
    /// </summary>
    /// <returns></returns>
    public async Task<IEnumerable<PttMessage>> GetMessages(
        string username,
        int page = 0)
    {
        var pttUrl = $"https://www.pttweb.cc/user/{username}?t=message&page={page}";

        var document = await this._browser.OpenAsync(pttUrl);
        if (document is null) return null;

        var listQuery = "div.thread-item";
        var titleQuery = "span.thread-title";
        var messageQuery = "span.yellow--text.text--darken-2";

        var contents = document.QuerySelectorAll(listQuery);
        document.Close();

        var messages = contents.Select(content => new PttMessage
        {
            Title = content
                .QuerySelector(titleQuery)
                .TextContent,
                
            Content = content
                .QuerySelectorAll(messageQuery)
                .Select(x => x.TextContent.Replace(": ", ""))
                .Where(x => x != username)
        });
        
        return messages;
    }
}

public class PttMessage
{
    public string Title { get; set; }
    public IEnumerable<string> Content { get; set; }
}

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