使用 NO 构造函数实例化 class 会导致 'does not contain constructor which takes 0 arguments' 错误

Question

我正在尝试从 Azure.Search.Documents 库中实例化一个 FacetResult：

var facetResult = new Azure.Search.Documents.Models.FacetResult(); 

VS 告诉我 class 不包含零参数的构造函数。当我检查 class 的元数据时 - 没有构造函数。

查看 the docs for the class 似乎可以确认没有构造函数 - 那么问题是什么？

I'm having the same issue with other library classes with no constructors such as Azure.Storage.Blobs.Models.BlobItem, while classes which appear to explicitly declare a parameterless constructor seem fine, such as System.Exception

非常感谢任何对此的帮助，它阻止了我的单元测试！

Answer 1

这个 class 的构造函数是内部的。 实例可能由工厂创建和返回。

//src code @ https://github.com/Azure/azure-sdk-for-net/
namespace Azure.Search.Documents.Models
{
    /// <summary> A single bucket of a facet query result. Reports the number of documents with a field value falling within a particular range or having a particular value or interval. </summary>
    public partial class FacetResult
    {
        /// <summary> Initializes a new instance of FacetResult. </summary>
        internal FacetResult()
        {
            AdditionalProperties = new ChangeTrackingDictionary<string, object>();
        }

        /// <summary> Initializes a new instance of FacetResult. </summary>
        /// <param name="count"> The approximate count of documents falling within the bucket described by this facet. </param>
        /// <param name="additionalProperties"> Additional Properties. </param>
        internal FacetResult(long? count, IReadOnlyDictionary<string, object> additionalProperties)
        {
            Count = count;
            AdditionalProperties = additionalProperties;
        }

https://github.com/Azure/azure-sdk-for-net/blob/4162f6fa2445b2127468b9cfd080f01c9da88eba/sdk/search/Azure.Search.Documents/src/Generated/Models/FacetResult.cs