小编Jat*_*hvi的帖子

我正在尝试从新的REST API中检索多个数据,但我有一个奇怪的问题.如果我在集合上使用$ expand,那么它就不起作用.

请求是:

GET [Oranization URL]/api/data/v8.0/accounts?$expand=contact_customer_accounts HTTP/1.1
Accept: application/json
Content-Type: application/json; charset=utf-8
OData-MaxVersion: 4.0
OData-Version: 4.0

并回应:

{
"error": {
    "code": "",
    "message": "Expansion of navigation properties isn\u2019t supported on entity collections.",
    "innererror": {
        "message": "Expansion of navigation properties isn\u2019t supported on entity collections.",
        "type": "Microsoft.Crm.CrmHttpException",
        "stacktrace": "   at Microsoft.Crm.Extensibility.OData.CrmODataUtilities.ThrowIfSelectClauseHasNavigationProperty(SelectExpandClause selectExpandClause, Boolean isCalledFromEntitySet)\r\n   at Microsoft.Crm.Extensibility.OData.CrmODataServiceDataProvider.RetrieveEdmEntityCollection(CrmODataExecutionContext context, String entityCollectionName, ODataQueryOptions queryOptions)\r\n   at Microsoft.Crm.Extensibility.OData.EntityController.GetEntitySetInternal(String entitySetName, String castEntityName, CrmODataExecutionContext context, CrmEdmEntityObjectCollection crmEdmEntityObjectCollection, ODataQueryOptions queryOptions)\r\n   at Microsoft.Crm.Extensibility.OData.EntityController.GetEntitySet(String entitySetName)\r\n   at lambda_method(Closure , …

Count()扫描所有元素,因此if (list.Count() == 1)如果enumerable包含很多元素,则效果不佳.

Single()如果没有一个元素,则抛出异常.使用try { list.Single(); } catch(InvalidOperationException e) {}是笨拙和低效的.

SingleOrDefault()如果有多个元素,则抛出异常,因此if (list.SingleOrDefault() == null)(假设TSource是引用类型)对大小大于1的可枚举不起作用.

我有一个通用方法SendHttpRequest<TRequest, TResponse>，它接受请求类型和响应类型作为其通用参数输入。响应类型可以是布尔值或表示响应的类。

我的任务是返回true方法内发出的 HTTP 请求是否成功并且TResponse是bool. 如果TResponse是不同类型，我需要将响应内容反序列化为TResponse对象。返回true会产生编译时错误。有没有办法让单个方法同时支持布尔和非布尔返回类型？

private async Task<TResponse> SendHttpRequest<TRequest, TResponse>(TRequest request)
{
    using (var client = new HttpClient())
    {
        client.BaseAddress = "http://example.com/";

        var response = await client.PostAsJsonAsync("api_path", request).ConfigureAwait(false);

        if (!response.IsSuccessStatusCode)
        {
            throw new MyException(response);
        }

        if (typeof (TResponse) == typeof (bool))
        {
            return true; // Generates compile-time error
        }
        else
        {
            var content = await response.Content.ReadAsStringAsync().ConfigureAwait(false);
            return JsonConvert.DeserializeObject<TResponse>(content);
        }
    }
}