mongodb上按对象的子集合项属性查询

Question

我正在存储以下集合：

{
    "_id" : ObjectId("59ffdb0c70a6560df428aaa3"),
    "name" : "Contact Information",
    "description" : "Basic contact information about myself",
    "questions" : [ 
        {
            "caption" : "First Name",
            "value" : ""
        }, 
        {
            "caption" : "Last Name",
            "value" : ""
        }, 
        {
            "caption" : "Email",
            "value" : ""
        }, 
        {
            "caption" : "Date of bith (mm/dd/yyyy)",
            "value" : ""
        }, 
        {
            "caption" : "Street Address",
            "value" : ""
        }, 
        {
            "caption" : "Address Line 2",
            "value" : ""
        }, 
        {
            "caption" : "State",
            "value" : ""
        }, 
        {
            "caption" : null,
            "value" : null
        }, 
        {
            "caption" : "Postal Code",
            "value" : ""
        }, 
        {
            "caption" : "Country",
            "value" : ""
        }
    ]

我需要根据父属性“名称”或问题集和属性“标题”进行查询。

因此，我构建了以下查询：

var result =(from Query in this.CoreService.QuestionCategoriesCollection().AsQueryable()
                            from Questions in Query.questions
                            where Questions.caption.ToLower().Contains(filter.ToLower())
                            select Query).ToList();

但是，当查询运行时，我会收到以下异常：

异常已发生:CLR/System.NotSupportdException--“System.NotSupportedException”类型的异常发生在MongoDB.Driver.dll中，但未在用户代码中处理：'$project或$group不支持{document}‘。(在MongoDB.Driver.Linq.Translators.AggregateLanguageTranslator.TranslateValue(Expression节点)在MongoDB.Driver.Linq.Translators.AggregateLanguageTranslator.TranslateMapping(ProjectionMapping映射)在MongoDB.Driver.Linq.Translators.QueryableTranslator.TranslateProjectValue(Expression选择器(在MongoDB.Driver.Linq.Translators.QueryableTranslator.TranslateSelectMany(SelectManyExpression节点)在MongoDB.Driver.Linq.Translators.QueryableTranslator.TranslateWhere(WhereExpression节点)在MongoDB.Driver.Linq.Translators.QueryableTranslator.TranslateSelect(SelectExpression节点)(在MongoDB.Driver.Linq.Translators.QueryableTranslator.TranslatePipeline(PipelineExpression节点)在MongoDB.Driver.Linq.Translators.QueryableTranslator.Translate(Expression节点，MongoDB.Driver.IAsyncCursorSourceExtensions.ToListTDocument at projectname.Services.Questions.GetQuestions(String filter) ( c:\developerment\project\project\Service\Questions.cs:line 24 at projectnameAPI.Controllers.QuestionsController.Get(String filter) ) c:\developerment\project\project\Controllers\QuestionsController.cs:line 31 at Microsoft.Extensions.Internal.ObjectMethodExecutor.Execute(Object target，( Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.d__12.MoveNext()的Object[]参数)

我不知道用linq编写查询的其他方法是什么。

Answer 1

最后，我重写了对此的查询。

    var result =this.CoreService.QuestionCategoriesCollection().Find(c=>c.name.ToLower().Contains(filter.ToLower())
    || c.questions.Any(q=>q.caption.ToLower().Contains(filter.ToLower())));

Answer 2

更干净但更原始的方式。给定以下集合模式示例：

public class Parent
{
    public IEnumerable<Child> Children { get; set; }
}

public class Child
{
    public string Id { get; set; }
}

通过子id获取父母的身份：

var dictionary = new Dictionary<string, object>
{
    "Children.Id" : "childId"
}
var data = this.ParentCollection().Find(new MongoDB.Driver.CommandDocument(dictionary));