Question

以下是我的模型，这是我从https://docs.microsoft.com/en-us/aspnet/web-api/overview/getting-started-with-aspnet-web-api/build-a-single-page-application-spa-with-aspnet-web-api-and-angularjs下载的源代码：我按照说明进行操作。

public class TriviaQuestion
{
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }

    [Required]
    public string Title { get; set; }

    public virtual List<TriviaOption> Options { get; set; }
}


  public class TriviaOption
    {
        [Column(Order = 1), DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public int Id { get; set; }

        [Required]
        public string Title { get; set; }

        [Column(Order = 0), ForeignKey("TriviaQuestion")]
        public int QuestionId { get; set; }

        [JsonIgnore]
        public virtual TriviaQuestion TriviaQuestion { get; set; }

        [JsonIgnore]
        public bool IsCorrect { get; set; }
    }

这是我的控制器，我收到的错误是“q.Count无法将方法组分配给匿名类型的主题。”：

private async Task<TriviaQuestion> NextQuestionAsync(string userId)
        {
            var lastQuestionId = await this.db.TriviaAnswers
                .Where(a => a.UserId == userId)
                .GroupBy(a => a.QuestionId)
                .Select(g => new { QuestionId = g.Key, Count = g.Count() })
                .OrderByDescending(q => new { **q.Count**, QuestionId = q.QuestionId })
                .Select(q => q.QuestionId)
                .FirstOrDefaultAsync();

            var questionsCount = await this.db.TriviaQuestions.CountAsync();

            var nextQuestionId = (lastQuestionId % questionsCount) + 1;
            return await this.db.TriviaQuestions.FindAsync(CancellationToken.None, nextQuestionId);
        }

Answer 1

qoute不是匿名类型字段的有效名称，您需要为其设置一个与QuestionId相同的名称

var names = ["John", "James", "Joe", "Justin"];
var quotes = [["Help me.", "Blah blah blah blah", "Blah blah blah"],["Blah blah blah", "Quote here"],["sample qoute"],["sample qoute again"]];

function whoSaidThis(qoute){
    //Iterate over qoutes array
    for(var i=0;i<quotes.length;i++) {
        //check if any of the items in qoutes array contain the qoute 
        if(quotes[i].indexOf(qoute) !== -1 ) {
            break;
        }
    }
    //returns undefined if qoute not foundin the qoutes array
    return i === quotes.length ? undefined : names[i] + " says : " + qoute;
};

console.log(whoSaidThis("sample qoute"));

您还可以将orderby拆分为OrderByDecending和ThenByDecending。

q.Count

如果您正在使用IQueryable对象，它最终可能会更好地查询服务器。

使用lambda查询分配方法组时，Async方法触发错误

1 个答案: