Question

我正在使用MongoDB $addToSet，如下所示：

.AddToSet(report => report.EngineReports, engineReport);

EngineReport是类，而不是MongoDB文档中的字符串或整数，它是类FileAggregationReport中的一部分：

public class FileAggregateReport
{        
    public Guid FileId { get; set; }

    public Guid CorrelationId { get; set; }

    public List<EngineReport> EngineReports { get; set; }      

}

现在我的问题是我有重复项，因为如果我有2个具有相同ID但其他属性不同的对象，则会将这2个类添加到集合中。

示例：

头等舱

new EngineReport()
    {
         EngineType = EngineType.TypeA,
         Summary = "test1"
    }

第二堂课

new EngineReport()
    {
         EngineType = EngineType.TypeA,
         Summary = "test2"
    }

因此，当我使用addToSet将其添加到EngineReports时，我的问题是2个类，但我只想添加一个，是否可以？

如何在addToset之前检查此类是否与集合中的ID相同？

Answer 1

来自$addToSet文档：

如果值为文档，则如果数组中的现有文档与要添加的文档完全完全匹配，则MongoDB会确定该文档为重复文档；即现有文档具有完全相同的相同字段和值，且这些字段的顺序相同。

因此，这对您的情况没有帮助。

您可以采用其他方法，并在更新操作中更改过滤器部分。例如，假设当前您通过FileId字段进行匹配。您可以添加其他检查，以确保更新的文档中没有EngineType.TypeA。这将对您尝试插入的第一个EngineReport有效，但对于第二个var filterBuilder = Builders<FileAggregateReport>.Filter; var regularFilter = filterBuilder.Eq(x => x.FileId, fileId); var engineType = Builders<EngineReport>.Filter.Eq(x => x.EngineType, EngineType.TypeA); var engineTypeFilter = filterBuilder.ElemMatch(f => f.EngineReports, engineType); var combinedFilter = filterBuilder.And(regularFilter, filterBuilder.Not(engineTypeFilter)); var updateBuilder = Builders<FileAggregateReport>.Update; var update1 = updateBuilder.Push(x => x.EngineReports, engineReport1); var update2 = updateBuilder.Push(x => x.EngineReports, engineReport2); myCollection.UpdateOne(combinedFilter, update1); // 1 document affected myCollection.UpdateOne(combinedFilter, update2); // 0 documents affected，则不会更新任何文档：

/// Updates The Contents Of Each Node Added To Our NodesAdded Array
///
/// - Parameters:
///   - nodes: [SCNNode]
///   - pointOfView: SCNNode
func updateScaleFromCameraForNodes(_ nodes: [SCNNode], fromPointOfView pointOfView: SCNNode){

    nodes.forEach { (node) in

        //1. Get The Current Position Of The Node
        let positionOfNode = SCNVector3ToGLKVector3(node.worldPosition)

        //2. Get The Current Position Of The Camera
        let positionOfCamera = SCNVector3ToGLKVector3(pointOfView.worldPosition)

        //3. Calculate The Distance From The Node To The Camera
        let distanceBetweenNodeAndCamera = GLKVector3Distance(positionOfNode, positionOfCamera)

        //4. Animate Their Scaling & Set Their Scale Based On Their Distance From The Camera
        SCNTransaction.begin()
        SCNTransaction.animationDuration = 0.5
        switch distanceBetweenNodeAndCamera {
        case 0 ... 0.5:
            node.simdScale = simd_float3(0.25, 0.25, 0.25)
        case 0.5 ... 1:
            node.simdScale = simd_float3(0.5, 0.5, 0.5)
        case 1 ... 1.5:
            node.simdScale = simd_float3(1, 1, 1)
        case 1.5 ... 2:
            node.simdScale = simd_float3(1.5, 1.5, 1.5)
        case 2 ... 2.5:
            node.simdScale = simd_float3(2, 2, 2)
        case 2.5 ... 3:
            node.simdScale = simd_float3(2.5, 2.5, 2.5)
        default:
            print("Default")
        }
        SCNTransaction.commit()
    }

}

在mongoDB中，函数AddToSet添加重复项

1 个答案: