具有组展开和项目的MongoDb C#类型聚合

本文介绍了具有组展开和项目的MongoDb C#类型聚合的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我有一个这样的收藏集:

I have a collection like this:

[{ "_id": 1, "OtherProperties": 100 "PersonInventory": [{ "FirstName": "Joe", "MiddleName": "Bob", "LastName": "Blogs", "PersonId": 1 }] },{ "_id": 2, "OtherProperties": 1005 "PersonInventory": [{ "FirstName": "Joe", "MiddleName": "Bob", "LastName": "Blogs", "PersonId": 1 }] }]

我正在尝试使用此处较新的类型推断mongodb c#驱动程序语法在根文档中选择所有唯一的人.

And I am trying to select all the unique persons in the root docs using here newer type inference mongodb c# driver syntax.

到目前为止，已尝试过此方法，但收到错误消息，指出该方法不可用(我认为这与分组有关)，有人可以告诉我我要去哪里了吗?

Tried this so far but getting errors saying the method is not available (i think this is to do with the grouping), can anyone show me where I am going wrong?

collection.Aggregate() .Match(m => m.PersonInventory.Count > o) .Unwind<RootDoc, Person>(t => t.PersonInventory) .Group(k => k.PersonId, g => g.First()) .ToListAsync();

型号:

public class Person { [BsonId] public long PersonId { get; set; } public string FirstName { get; set; } public string MiddleName { get; set; } public string LastName { get; set; } } public class RootDoc { public long Id{ get; set; } //more props public IList<Person> PersonInventory { get; set; } }

仅供参考，错误消息是Specified method is not supported..

FYI the error message is Specified method is not supported..

堆栈跟踪:

at MongoDB.Driver.Linq.Processors.AccumulatorBinder.GetAccumulatorArgument(Expression node) at MongoDB.Driver.Linq.Processors.AccumulatorBinder.TryGetAccumulatorTypeAndArgument(PipelineExpression node, AccumulatorType& accumulatorType, Expression& argument) at MongoDB.Driver.Linq.Processors.AccumulatorBinder.VisitPipeline(PipelineExpression node) at MongoDB.Driver.Linq.Expressions.PipelineExpression.Accept(ExtensionExpressionVisitor visitor) at MongoDB.Driver.Linq.Expressions.ExtensionExpression.Accept(ExpressionVisitor visitor) at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node) at MongoDB.Driver.Linq.Processors.EmbeddedPipeline.EmbeddedPipelineBinder.Bind(Expression node, IBindingContext parent) at MongoDB.Driver.Linq.Processors.SerializationBinder.BindEmbeddedPipeline(MethodCallExpression node) at MongoDB.Driver.Linq.Processors.SerializationBinder.VisitMethodCall(MethodCallExpression node) at System.Linq.Expressions.MethodCallExpression.Accept(ExpressionVisitor visitor) at MongoDB.Driver.Linq.Processors.SerializationBinder.Visit(Expression node) at MongoDB.Driver.Linq.Translators.AggregateGroupTranslator.BindGroup[TKey,TDocument,TResult](PipelineBindingContext bindingContext, Expression`1 groupProjector, IBsonSerializer`1 parameterSerializer, Expression keySelector) at MongoDB.Driver.Linq.Translators.AggregateGroupTranslator.Translate[TKey,TDocument,TResult](Expression`1 idProjector, Expression`1 groupProjector, IBsonSerializer`1 parameterSerializer, IBsonSerializerRegistry serializerRegistry, ExpressionTranslationOptions translationOptions) at MongoDB.Driver.GroupExpressionProjection`3.Render(IBsonSerializer`1 documentSerializer, IBsonSerializerRegistry serializerRegistry) at MongoDB.Driver.PipelineStageDefinitionBuilder.<>c__DisplayClass19_0`2.<Group>b__0(IBsonSerializer`1 s, IBsonSerializerRegistry sr) at MongoDB.Driver.DelegatedPipelineStageDefinition`2.Render(IBsonSerializer`1 inputSerializer, IBsonSerializerRegistry serializerRegistry) at MongoDB.Driver.AppendedStagePipelineDefinition`3.Render(IBsonSerializer`1 inputSerializer, IBsonSerializerRegistry serializerRegistry) at MongoDB.Driver.MongoCollectionImpl`1.<AggregateAsync>d__22`1.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at MongoDB.Driver.MongoCollectionImpl`1.<UsingImplicitSessionAsync>d__101`1.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at MongoDB.Driver.IAsyncCursorSourceExtensions.<ToListAsync>d__16`1.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult() at App.Application.Services.CacheSyncService.<GetAllCrewAsync>d__9.MoveNext() in C:\Users\gdp\Sites\app\Services\CacheSyncService.cs:line 77 --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult() at App.Application.Services.Sync.ReferenceDataSyncService.<ResolveCrewReferences>d__6.MoveNext() in C:\Users\gdp\Sites\app\Services\Sync\ReferenceDataSyncService.cs:line 46 --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult() at App.API.Controllers.DataSyncController.<ResolveCrewReferences>d__3.MoveNext() in C:\Users\gdp\Sites\app\Controllers\DataSyncController.Triggers.cs:line 87 --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Threading.Tasks.TaskHelpersExtensions.<CastToObject>d__1`1.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.Controllers.ApiControllerActionInvoker.<InvokeActionAsyncCore>d__1.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.Controllers.ActionFilterResult.<ExecuteAsync>d__5.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.Controllers.ExceptionFilterResult.<ExecuteAsync>d__6.MoveNext()

推荐答案

我在mongodb Jira页面上进行了一些挖掘，似乎不支持变量$$ ROOT，因此不支持上述查询.

I did some digging on the mongodb Jira pages, it looks like there isn't support for the variable $$ROOT, so the above queries are not supported.