如何将所有双和字符串数据类型分隔到实例的集合中

Question

这是我的类结构和样本数据，

public class CollectionProperty
{
    public string Name { get; set; }

    public object Value { get; set; }
    public string DataType { get; set; }
}

public class Instance
{
    public string Name { get; set; }
    public List<CollectionProperty> CollectionProperties { get; set; }
}

public class CollectionResult
{
    public string Asset { get; set; }
    public List<Instance> Instances { get; set; }
}

===============================================================================================

var collectionResult = new CollectionResult
        {
            Asset = "A1",
            Instances = new List<Instance>
            {
                new Instance
                {
                    Name = "Instance-1",
                    CollectionProperties = new List<CollectionProperty>
                    {
                        new CollectionProperty {Name = "N1", Value = 10, DataType = "Double"},
                        new CollectionProperty {Name = "N2", Value = "S1", DataType = "String"}
                    }
                },
                new Instance
                {
                    Name = "Instance-2",
                    CollectionProperties = new List<CollectionProperty>
                    {
                        new CollectionProperty {Name = "N1", Value = 20, DataType = "Double"},
                        new CollectionProperty {Name = "N2", Value = "S2", DataType = "String"}
                    }
                }
            }
        };

现在基于DataType，我想像下面的集合那样进行隔离。示例为Double，类似于string。在collectionResult中，我需要从各个实例中添加Asset和所有双重数据类型的集合属性。这个是可能的吗？

var collectionResult = new CollectionResult
        {
            Asset = "A1",
            DoubleInstances = new List<Instance>
            {
                new Instance
                {
                    Name = "Instance-1",
                    CollectionProperties = new List<CollectionProperty>
                    {
                        new CollectionProperty {Name = "N1", Value = 10, DataType = "Double"}
                    }
                },
                new Instance
                {
                    Name = "Instance-2",
                    CollectionProperties = new List<CollectionProperty>
                    {
                        new CollectionProperty {Name = "N1", Value = 20, DataType = "Double"}
                    }
                }
            }
        };

Answer 1

在这种情况下，创建一个新的CollectionResult实例并使用LINQ进行属性筛选非常简单。您可以使用Enumerable.Select()创建新实例，只使用Enumerable.Where()筛选双倍实例。

var doubleCollection = new CollectionResult
{
    Asset = collectionResult.Asset,
    Instances = collectionResult.Instances.Select(x => new Instance { 
        Name = x.Name, 
        CollectionProperties = x.CollectionProperties.Where(cp => cp.DataType == "Double").ToList() 
    }).ToList()
};

还可以创建一个方法，通过Func<CollectionProperty, bool>谓词选择器进行筛选。如果按照您决定要通过与CollectionProperty不同的属性进行筛选的跟踪，这种方法可能很有用。您只需传递一个不同的谓词。

private static CollectionResult FilterCollectionByProperty(CollectionResult collectionResult, Func<CollectionProperty, bool> selector)
{
    return new CollectionResult
    {
        Asset = collectionResult.Asset,
        Instances = collectionResult.Instances.Select(x => new Instance
        {
            Name = x.Name,
            CollectionProperties = x.CollectionProperties.Where(selector).ToList()
        }).ToList()
    };
}

并分别或在CollectionResult中创建IEnumerable<CollectionResult>对象。

var types = new List<string> { "Double", "String" };

// Separate collections
var doubleCollection = FilterCollectionByProperty(collectionResult, x => x.DataType == "Double");
var stringCollection = FilterCollectionByProperty(collectionResult, x => x.DataType == "String");

// List of collections
var collectionList = types.Select(t => FilterCollectionByProperty(collectionResult, x => x.DataType == t));

另一种选择是直接通过DataType传递和过滤，然后不需要传递Func<CollectionProperty, bool>谓词。缺点是，该方法是固定的过滤仅由DataType。

private static CollectionResult FilterCollectionByDataType(CollectionResult collectionResult, string dataType)
{
    return new CollectionResult
    {
        Asset = collectionResult.Asset,
        Instances = collectionResult.Instances.Select(x => new Instance
        {
            Name = x.Name,
            CollectionProperties = x.CollectionProperties.Where(cp => cp.DataType == dataType).ToList()
        }).ToList()
    };
}

也可以创建为单独的CollectionResult对象或IEnumerable<CollectionResult>。

var types = new List<string> { "Double", "String" };

// Separate collections
var doubleCollection = FilterCollectionByDataType(collectionResult, "Double");
var stringCollection = FilterCollectionByDataType(collectionResult, "String");

// List of collections
var collectionList = types.Select(t => FilterCollectionByDataType(collectionResult, t));