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我试图弄清楚如何将这样的复杂查询转换为编译查询并保持代码干净。这个不是那么复杂，但它是一个例子，我有更复杂的查询。

所以我想转换这个投影查询：

public List<GetAnswers> GetAnswers(int pQuestionId, string pSearch,   int?       pSkip, int? pTake, GetAnswersOrderBy pOrderBy, bool  pOrderByIsAscending, out int pTotalNumberOfLines)
{
    string search = pSearch.ToUpper().Replace(" ", "");
    string languageCode = Thread.CurrentThread.CurrentCulture.ToString().ToLower().Substring(0, 2);
    IQueryable<Answer> query = this.Context.Set<Answer>();
    //Filter question by questionnaire
    query = query.Where(w => w.QuestionID == pQuestionId);

    if (!string.IsNullOrEmpty(pSearch))
        query = query.Where(w => (w.AnswerTranslations.Any(a => languageCode == a.LanguageCode)
                         ? w.AnswerTranslations.FirstOrDefault(a => languageCode == a.LanguageCode).Label
                         : w.AnswerTranslations.OrderBy(o => o.Language.Priority).FirstOrDefault().Label)
                         .ToUpper().Replace(" ", "")
                         .Contains(search));
    switch (pOrderBy)
    {
        case GetAnswersOrderBy.CorrectAnswer:
            query = pOrderByIsAscending ? query.OrderBy(w => w.CorrectAnswer) : query.OrderByDescending(w => w.CorrectAnswer);
            break;
        case GetAnswersOrderBy.ResponseCount:
            query = pOrderByIsAscending ? query.OrderBy(w => w.ResponseCount) : query.OrderByDescending(w => w.ResponseCount);
            break;
        default:
            break;
    }
    pTotalNumberOfLines = query.Count();

    var pagedQuery = query.Skip(pSkip ?? 0)
                         .Take(pTake ?? pTotalNumberOfLines);
    var projectedQuery = pagedQuery.Select(s =>
        new
        {
            Answer = s,
            s.AnswerTranslations,
            AnswerTranslationsLanguages = s.AnswerTranslations.Select(qt => qt.Language),
        }).ToList();
    return projectedQuery.Select(s => new GetAnswers()
    {
        Id = s.Answer.Id,
        Label = s.Answer.Label,
        CorrectAnswer = s.Answer.CorrectAnswer,
        Feedback = s.Answer.Feedback,
        Weighting = s.Answer.Weighting
    }).ToList();
}

像这样保持代码干净：

public List<Answer> GetAnswers(int pQuestionId, string pSearch,   int?       pSkip, int? pTake, GetAnswersOrderBy pOrderBy, bool  pOrderByIsAscending, out int pTotalNumberOfLines)
{
    var compiledQuery = CompiledGetAnswers(params...);

    var projectedQuery = compiledQuery .Select(s =>
        new
        {
            Answer = s,
            s.AnswerTranslations,
            AnswerTranslationsLanguages = s.AnswerTranslations.Select(qt => qt.Language),
        }).ToList();

    return projectedQuery.Select(s => new GetAnswers()
    {
        Id = s.Answer.Id,
        Label = s.Answer.Label,
        CorrectAnswer = s.Answer.CorrectAnswer,
        Feedback = s.Answer.Feedback,
        Weighting = s.Answer.Weighting
    }).ToList();
} 

public static Func<AppDbContext, Answer, IQueryable<Answer>> CompiledGetAnswers(int pQuestionId, string pSearch,   int?       pSkip, int? pTake, GetAnswersOrderBy pOrderBy, bool  pOrderByIsAscending, out int pTotalNumberOfLines)
{
    string search = pSearch.ToUpper().Replace(" ", "");
    string languageCode = Thread.CurrentThread.CurrentCulture.ToString().ToLower().Substring(0, 2);
    IQueryable<Answer> query = this.Context.Set<Answer>();
    //Filter question by questionnaire
    query = query.Where(w => w.QuestionID == pQuestionId);

    if (!string.IsNullOrEmpty(pSearch))
        query = query.Where(w => (w.AnswerTranslations.Any(a => languageCode == a.LanguageCode)
                         ? w.AnswerTranslations.FirstOrDefault(a => languageCode == a.LanguageCode).Label
                         : w.AnswerTranslations.OrderBy(o => o.Language.Priority).FirstOrDefault().Label)
                         .ToUpper().Replace(" ", "")
                         .Contains(search));
    switch (pOrderBy)
    {
        case GetAnswersOrderBy.CorrectAnswer:
            query = pOrderByIsAscending ? query.OrderBy(w => w.CorrectAnswer) : query.OrderByDescending(w => w.CorrectAnswer);
            break;
        case GetAnswersOrderBy.ResponseCount:
            query = pOrderByIsAscending ? query.OrderBy(w => w.ResponseCount) : query.OrderByDescending(w => w.ResponseCount);
            break;
        default:
            break;
    }
    pTotalNumberOfLines = query.Count();

    var pagedQuery = query.Skip(pSkip ?? 0)
                         .Take(pTake ?? pTotalNumberOfLines);
    return CompiledQuery(AppDbContext db, Answer a) => pagedQuery;
}
4

1 回答 1

0

我猜你所说的干净是“更具可读性”。你实际上正在这样做。我的建议是将您的复杂查询放入一个方法中并给它一个有意义的名称。

例如，如果人们不查看您的查询，他们将无法理解您在以下代码中在做什么

query = query.Where(w => (w.AnswerTranslations.Any(a => languageCode == a.LanguageCode)
                         ? w.AnswerTranslations.FirstOrDefault(a => languageCode == a.LanguageCode).Label
                         : w.AnswerTranslations.OrderBy(o => o.Language.Priority).FirstOrDefault().Label)
                         .ToUpper().Replace(" ", "")
                         .Contains(search));

你可以做一个扩展类

public static class MyQueryExtension
{
    public static IQueryable<Answer> SearchAnswersByLanguageCode(this IQueryable<Answer> query, string languageCode, string search)
    { 
        return query.Where(w => (w.AnswerTranslations.Any(a => languageCode == a.LanguageCode)
                     ? w.AnswerTranslations.FirstOrDefault(a => languageCode == a.LanguageCode).Label
                     : w.AnswerTranslations.OrderBy(o => o.Language.Priority).FirstOrDefault().Label)
                     .ToUpper().Replace(" ", "")
                         .Contains(search))
    }
}

并在您的代码中调用它

query = query.SearchAnswersByLanguageCode(languageCode, search);

然后你就可以让你的主要方法干净易读

public static Func<AppDbContext, Answer, IQueryable<Answer>> CompiledGetAnswers(int pQuestionId, string pSearch,   int?       pSkip, int? pTake, GetAnswersOrderBy pOrderBy, bool  pOrderByIsAscending, out int pTotalNumberOfLines)
{
    //Do something
    if (!string.IsNullOrEmpty(pSearch))
        query = query.SearchAnswersByLanguageCode(languageCode, search);

    query = query.GetItOrdered(parameters);

    //Do something
}
于 2017-03-10T17:48:02.190 回答