C# Mongo 驱动程序：使用连接和 UpdateManyAsync 更新查询

Question

I have 2 collections

ProductCategory

_id name active

Product

_id CategoryId DateUpdated

I can do the update in one collection by creating a filter and using UpdateManyAsync, like this:

var update = Builders<ProductCategory>.Update
                .Set(x => x.Active ,false);


var filter = Builders<ProductCategory>.Filter.Where(
                x => x.Active == true);

var result = await Collection.UpdateManyAsync(filter, update);

Now I want to update Active field on ProductCategory if any documents with DateUpdated more than 1 day compared to current date

it may the same as sql query:

UPDATE A
SET active = false
FROM ProductCategory A
JOIN Product B
    ON A._id= B.CategoryId
WHERE DATEDIFF(Getdate(), B.DateCreated) >= 1

Answer 1

afaik you cannot update entities based on the result of a lookup/join in mongodb via a single command. instead you'd have to first retrieve the IDs of categories and then do the update operation like below:

var inactiveCatIDs = collection.AsQueryable()
                               .Where(p => p.DateUpdated <= DateTime.UtcNow.AddDays(-1))
                               .Select(p => p.CategoryID)
                               .ToArray();

collection.UpdateMany(c => inactiveCatIDs.Contains(c.ID),
                      Builders<ProductCategory>.Update.Set(c => c.Active, false));

here's a test program:

 using MongoDB.Entities; using MongoDB.Entities.Core; using System; using System.Linq; namespace StackOverflow { public class Product : Entity { public DateTime DateUpdated { get; set; } public string CategoryID { get; set; } } public class ProductCategory : Entity { public bool Active { get; set; } } public class Program { private static void Main(string[] args) { new DB("test", "localhost"); var cat1 = new ProductCategory { Active = true }; cat1.Save(); var cat2 = new ProductCategory { Active = true }; cat2.Save(); (new[] { new Product { CategoryID = cat1.ID, DateUpdated = DateTime.UtcNow.AddDays(-1.5) }, new Product { CategoryID = cat2.ID, DateUpdated = DateTime.UtcNow }}).Save(); ; var inactiveCatIDs = DB.Queryable<Product>() .Where(p => p.DateUpdated <= DateTime.UtcNow.AddDays(-1)) .Select(p => p.CategoryID) .ToArray(); DB.Update<ProductCategory>() .Match(c => inactiveCatIDs.Contains(c.ID)) .Modify(c => c.Active, false) .Execute(); } } }