c# - linq 查询可能缺少一些 from 值

Question

我正在从 JSON 中提取联系人，Data 中的联系人可能包含电子邮件和电话号码。

如果他们执行以下查询，则完美无缺:

var results = from d in json.Data
                from c in d.Contacts
                from e in c.Emails
                from p in c.Phones
                select new IoModel {Email = e.EmailValue, Id = d.Id, FullName = string.IsNullOrEmpty(c.Name) ? c.Name : d.DisplayName, Phone = p.PhoneNumber, DOB = d.CustomDOB};

如果数据没有电子邮件或电话，则它运行时不会出错，但不会返回联系人姓名。

有没有一种方法可以在不使用 if 和 and's 的情况下做到这一点，从而使代码更短更简洁？

这是一个缺少电子邮件的 JSON 示例:

{
    "data": [
        {
            "addresses": [], 
            "contacts": [
                {
                    "created_by": "user_ltUL3eXGPRWb5ghDeGTfOe9qjW0LeE2e4ouopLcSSWj", 
                    "date_created": "2017-12-28T17:13:00.392000+00:00", 
                    "date_updated": "2017-12-28T17:13:58.453000+00:00", 
                    "emails": [], 
                    "id": "cont_6hxxhz51ctlTnHfo8gA8cce0rthS1dJy1kguKAj148s", 
                    "integration_links": [
                        {
                            "name": "LinkedIn Search", 
                            "url": "https://www.linkedin.com/search/results/index/?keywords=John%20Doe"
                        }
                    ], 
                    "lead_id": "lead_3UzfxCgQHmw4BlGwElitHhlP6E7q9Tg3sdSkTl1CIXp", 
                    "name": "John Doe", 
                    "organization_id": "orga_PvgGx1opSZDsCHl73P8OoSFZUlJ3qsNGI2kwgoObM17", 
                    "phones": [
                        {
                            "phone": "+15555555555", 
                            "phone_formatted": "+1 555-555-5555", 
                            "type": "mobile"
                        }
                    ], 
                    "title": "Main Service", 
                    "updated_by": "user_ltUL3eXXPRWb5shDeGTfOe9qjP0LeE2e4ouopLcSSWj", 
                    "urls": []
                }
            ], 
            "created_by": "user_ltUL3eXXPRWb5shDeGTfOe9qjW0LeE2e4ouopLcSSWP", 
            "created_by_name": "John", 
            "custom": {
                "Date Of Birth": "1901-08-01", 
                "Department": "Main Service", 
                "Initial Service": "Main Service"
            }, 
            "custom.lcf_ufMH5ZhlR99zcdvJxKMxdgxcIbV4wtgTb3EdWDEkL8g": "1971-08-17", 
            "date_created": "2017-12-28T17:13:00.388000+00:00", 
            "date_updated": "2017-12-29T21:41:53.840000+00:00", 
            "description": "", 
            "display_name": "John Doe", 
            "html_url": "https://app.close.io/lead/lead_3UzfxCgQHmw4BlGwElitHhlP6E7q9Tg3sdSkTl1CIXp/", 
            "id": "lead_3UzfxCgQHmw4BlGwElitHhlP5E7q9Tg3sdSkTl1CIXp", 
            "integration_links": [
                {
                    "name": "Google Search", 
                    "url": "http://google.com/search?q=John%20Doe"
                }
            ], 
            "name": "", 
            "opportunities": [], 
            "organization_id": "orga_AvcGx4opSZDsCHl73H8OogDDUlJ3qsNGI2kwgoObA17", 
            "status_id": "stat_LpJu8FO72WgIob4qDDVnS4GEieoU41zmQ8xBquTvusm", 
            "status_label": "Established Patient", 
            "tasks": [], 
            "updated_by": "user_0JFRnl8QRvRhMhAlLz4JJxgmrzPeLs3xboxYyj5Pm80", 
            "updated_by_name": "BT", 
            "url": null
        }
    ], 
    "has_more": false, 
    "total_results": 1
}

Answer 1

因为我不知道你将 JSON 反序列化成什么，我只能在这里猜测一个解决方案，但我认为如果你在你的 Emails 上使用 DefaultIfEmpty() code> 和 Phones 集合，然后在 EmailValue 和 PhoneNumber 上使用 null 条件运算符，你应该得到你想要的结果:

var results = from d in json.Data
              from c in d.Contacts
              from e in c.Emails.DefaultIfEmpty()
              from p in c.Phones.DefaultIfEmpty()
              select new IoModel
              {
                  Email = e?.EmailValue,
                  Id = d.Id,
                  FullName = string.IsNullOrEmpty(c.Name) ? c.Name : d.DisplayName,
                  Phone = p?.PhoneNumber,
                  DOB = d.CustomDOB
              };