var memoed = MemoInfo.DBCollation.AsQueryable() .Where((t) => { var local = t.LastMemo.ToLocalTime(); return t.UserId == UserInfo.CurrentUser.Id && local < DateTime.Now; })

根据您提供的代码，这是一个LINQ查询表达式，用于从MemoInfo.DBCollation集合中获取当前用户的MemoInfo对象列表，其中最后一条Memo的本地时间早于当前时间。

具体来说，代码使用AsQueryable()方法将MemoInfo.DBCollation集合转换为可查询的IQueryable对象，然后使用Where()方法来筛选符合条件的对象。在Where()方法中，通过lambda表达式定义筛选条件，即UserId等于当前用户的Id，并且最后一条Memo的本地时间早于当前时间。

在lambda表达式中，使用了ToLocalTime()方法将DateTime类型的t.LastMemo转换为本地时间，然后与当前时间DateTime.Now进行比较。最后，查询结果将作为MemoInfo对象列表返回给变量memoed。

相关问题

var memoed = MemoInfo.DBCollation.AsQueryable() .Where((t) => { var local = t.LastMemo.ToLocalTime(); return t.UserId == UserInfo.CurrentUser.Id && local < DateTime.Now; })，语法错误

根据您提供的代码，似乎缺少一个分号(;)，该分号应该在代码的末尾。请尝试使用以下代码：

var memoed = MemoInfo.DBCollation.AsQueryable()
    .Where((t) =>
    {
        var local = t.LastMemo.ToLocalTime();
        return t.UserId == UserInfo.CurrentUser.Id && local < DateTime.Now;
    });

请注意，除了上述语法错误之外，该代码段本身是有效的，可以从MemoInfo.DBCollation集合中获取符合条件的MemoInfo对象列表，其中最后一条Memo的本地时间早于当前时间。

var Words = WordInfo.DBCollation.AsQueryable().Where(t => t.MemoTime == 0).Take(5).ToList(); BsonArray bsonArray = new BsonArray(); foreach (var model in Words) { bsonArray.Add(model.ToBson()); } // Convert the BsonArray to a byte array byte[] bsonBytes = bsonArray.ToBson();，报错：System.InvalidOperationException:“An Array value cannot be written to the root level of a BSON document.”

The error message indicates that you are trying to write an array value to the root level of a BSON document, which is not allowed.

In your code, you are trying to serialize a `BsonArray` object to a byte array using the `ToBson()` method. However, you cannot serialize an array value to the root level of a BSON document. Instead, you need to wrap the `BsonArray` object in a `BsonDocument` object before serializing it to a byte array.

Here's an updated example code snippet that should work:

using MongoDB.Bson;
using MongoDB.Driver;
using System.Collections.Generic;

// Assuming WordInfo class exists with a DBCollation property
List<WordInfo> words = WordInfo.DBCollation.AsQueryable().Where(t => t.MemoTime == 0).Take(5).ToList();

// Serialize the words list to a BsonArray
BsonArray bsonArray = new BsonArray();
foreach (var word in words)
{
    bsonArray.Add(word.ToBson());
}

// Wrap the BsonArray in a BsonDocument
BsonDocument bsonDocument = new BsonDocument
{
    { "Words", bsonArray }
};

// Convert the BsonDocument to a byte array
byte[] bsonBytes = bsonDocument.ToBson();

In this code snippet, we wrap the `BsonArray` object in a `BsonDocument` object with a key of "Words", and then serialize the `BsonDocument` to a byte array using the `ToBson()` method. This should prevent the "System.InvalidOperationException: An Array value cannot be written to the root level of a BSON document." error.