过滤器生成器在 C# mongoDB 驱动程序中引发异常

Posted 2023-02-16

【中文标题】过滤器生成器在 C# mongoDB 驱动程序中引发异常

【英文标题】：Filter Builder throwing an exception in C# mongoDB Driver

【发布时间】：2021-11-03 20:15:06

【问题描述】：

我正在尝试使用 c# mongo 驱动程序从 MongoDB 获取文档。

public class Record

    [BsonId]
    public ObjectId Id  get; set; 
    public string FirstName  get; set; 
    public string LastName  get; set; 
    public Data  get; set; 

public class Name

    public string FirstName  get; set; 
    public string LastName  get; set; 

var Names = new List<Names>;
Names.Add(new Name(FirstName = "abc", LastName = "xyz"));
Names.Add(new Name(FirstName = "123", LastName = "789"));
Names.Add(new Name(FirstName = "a1b2", LastName = "c7d8"));

我尝试了下面的查询来过滤和获取所需的文档。但此查询失败并引发异常。

FilterDefinition<Record> patentFilter = Builders<Record>.Filter.Where(y => Names.Any(x=> x.Name == y.Name && x.LastName == y.LastName));

例外

System.ArgumentException: 'Unsupported filter: Any(value(Name]).Where(((documentFirstName == documentFirstName) AndAlso (documentLastName == documentLastName)))).'

【问题讨论】：

异常表示这种过滤器不受类型化方式的支持，但您仍然可以将其定义为简单的 BsonDocument（而不是使用 Builder）并将其传递给您的方法，而不是 FilterDefinition

【参考方案1】：

答案迟到了。

建议：

生成nameFilters。

对于FirstName 和 ($and) LastName，每个 nameFilter 必须相等 ($eq)。

父过滤器 (filter) 将nameFilters 与$or 链接起来。

任何满足nameFilter 的文档都将被退回。

var names = new List<Name>();
names.Add(new Name  FirstName = "abc", LastName = "xyz" );
names.Add(new Name  FirstName = "123", LastName = "789" );
names.Add(new Name  FirstName = "a1b2", LastName = "c7d8" );

List<FilterDefinition<Record>> namefilters = new List<FilterDefinition<Record>>();

foreach (var name in names)

    FilterDefinition<Record> namefilter = Builders<Record>.Filter.And(
        Builders<Record>.Filter.Eq(x => x.FirstName, name.FirstName),
        Builders<Record>.Filter.Eq(x => x.LastName, name.LastName)
    );

    namefilters.Add(namefilter);


FilterDefinition<Record> filter = Builders<Record>.Filter.Or(namefilters);

var filteredRecords = _collection.Find(filter)
    .ToList();

MongoDB 查询

db.collection.find(
  $expr: 
    $or: [
      
        $and: [
          
            $eq: [
              "$FirstName",
              "abc"
            ]
          ,
          
            $eq: [
              "$LastName",
              "xyz"
            ]
          
        ]
      ,
      // Other name filters
    ]
  
)

Sample Mongo Playground