Question

业务逻辑：

我有三张桌子。在Referral l和Referrer表中ReferralInstance，many to many，Referra与Referer关系。向候选人提供推荐表格，填写工作申请表。用户发布的Referral表单显示给与请求公司关联的所有Referrer（aka Employee）。此外，请求公司中的员工可以选择"Accept"或"Reject"该配置文件（此详细信息在实例表中捕获）。

需要的行为：

现在，当候选人根据特定条件（如下所述）添加推荐表格时，我想检查此推荐请求是否已存在。如果它已经存在，那么我会显示警告/弹出窗口。

条件1：

当候选人刚刚发布推荐请求时。那么ReferralInstance表将是EMPTY，所以我需要检查CompanyId，CandidateId和SkillId是否匹配，如果所有这三个匹配现有的DB记录我想要将hasPreviousRequest设置为true

条件2：

候选人发布请求后SkillId，CompanyId和CandidateId匹配。还有很多员工（属于那个被要求的公司＆＃34;拒绝了他，但没有人接受，所以我想将hasPreviousRequest设置为true。

条件3：

当候选人发布推荐请求时，SkillId，CompanyId，CandidateId匹配，但推荐人之一已接受他作业，在这种情况下我想设置集{ {1}}至hasPreviousRequest。

以下是我的尝试：

false

在上面的尝试中，我做了两次相同的部分LINQ查询。要么我想要一个更好的LINQ来同时检查所有三个条件。如果没有，那么我想存储条件1中使用的LINQ查询，并在检查条件2时使用它。

如下所示：

[HttpPost]
public JsonResult CheckForExistingReferral(ReferralViewModel viewModel)
{
    bool hasPreviousRequest = false;
    var candidateId = User.Identity.GetUserId();
    // CHCEKING CONDITION ONE   
    if (_context.Referrals
        .Any(r => ((r.CandidateId == candidateId)
                       && (r.CompanyId == viewModel.CompanyId)
                       && (r.SkillId == viewModel.SkillId))))
    {
    // NOW CHECKING CONDITION TWO
        if (_context.Referrals
       .Any(r => ((r.CandidateId == candidateId)
                      && (r.CompanyId == viewModel.CompanyId)
                      && (r.SkillId == viewModel.SkillId))
                      && r.ReferralInstances
                      .Any(e => (e.ReferrerId != null) && (e.ReferralStatus == "Accepted"))))
        {
            hasPreviousRequest = false;
        }
        else
            hasPreviousRequest = true;

    }

    return Json(new { hasPreviousRequest = hasPreviousRequest });
}

修改

[HttpPost] public JsonResult CheckForExistingReferral(ReferralViewModel viewModel) { bool hasPreviousRequest = false; var candidateId = User.Identity.GetUserId(); var PartialLINQ = _context.Referrals .Any(r => ((r.CandidateId == candidateId) && (r.CompanyId == viewModel.CompanyId) && (r.SkillId == viewModel.SkillId))); if (PartialLiinq) { // SOMETHING LIKE THIS if (PartialLinq && r.ReferralInstances .Any(e => (e.ReferrerId != null) && (e.ReferralStatus == "Accepted")))) { hasPreviousRequest = false; } else hasPreviousRequest = true; } return Json(new { hasPreviousRequest = hasPreviousRequest }); }有4个属性：

Id PK 2. ReferrerId FK 3. ReferralID FK 4. ReferralStatus

Answer 1

[HttpPost]
public JsonResult CheckForExistingReferral(ReferralViewModel viewModel)
{
    bool hasPreviousRequest = false;
    var candidateId = User.Identity.GetUserId();
    // Do an outer join between the tables on ReferralID and select only a new Anonymous type that has referrerId
    // and status. If no record found in ReferralInstances then set status to empty.
    var result = (from r in  _context.Referrals
                 join ri in _context.ReferralInstances on r.ReferralID equals ri.ReferralID into refsInst
                 where ((ri.CandidateId == candidateId) && 
                        (ri.CompanyId == viewModel.CompanyId) && 
                        (ri.SkillId == viewModel.SkillId))
                 from rs in refsInst.DefaultIfEmpty() 
                 select new {ReferenceEquals = rs.ReferrerId,  Status = rs == null ? "":rs.ReferralStatus})
                .ToList(); 
    // This covers third condition            
    if(result.Any(p => p.ReferrerId != null && p.Status == "Accepted"))  
    {
        hasPreviousRequest = false;
    }
    // This covers first and second conditions. If nothing found in ReferralInstances, the status will be empty
    if(result.Any() && result.All(p => p.Status != "Accepted")) 
    {
        hasPreviousRequest = true;
    }  

    return Json(new { hasPreviousRequest = hasPreviousRequest });
}

如何将LINQ查询分配给变量，然后在代码中使用它

1 个答案: