检查数据库中是否存在实体 [英] Check if entity exists in database

问题描述

大家好，我们想知道是否有人可以告诉我，如果我在正确的道路上，我试图检查数据库中是否存在数据（iccid）。检查下面的代码。

Hi guys wondering if guys could tell me if i'm on the right path, im trying to check if data(iccid) exists in database. Check code below.

public ActionResult Add(SIMCardInfoView model)
        {
            if (ModelState.IsValid)
            {
                SIMCard simCard = null;
                //Check if entity exists in database 
                simCard = db.SIMCards.FirstOrDefault(card => card.ICCID == model.ICCID);

                if (model.IsNew)
                {
                    // The posted model indicated this is a new simcard.
                    simCard = new SIMCard();
                    db.SIMCards.Add(simCard);
                }
                else
                {
                    // This model already exists
                    // The entity could not be saved, add an error and return to the view.
                    ModelState.AddModelError("Validation", "Unable to save this simcard. The database entity exists in the database.");
                    UpdateDetailViewModel(model);
                    return View(model);
                }

                //TODO:Default group
                //simCard.GroupID = 1;
                simCard.CapturedBy = "Test";
                simCard.DateCaptured = DateTime.Now;
                simCard.ICCID = model.ICCID;
                simCard.IMSI = model.IMSI;
                simCard.MSISDN = model.MSISDN;
                simCard.NetworkID = model.NetworkID;
                simCard.PackageID = model.PackageID;
                simCard.SIMCardID = model.SIMCardID;
                simCard.SubBatchID = model.SubBatchID;
                simCard.TrackingCode = model.TrackingCode;

                db.SaveChanges();
                return RedirectToAction("Index");
            }
            else
            {
                // The user did not post a valid model.
                // To debug this, check the errors inside the modelstate object.
                UpdateDetailViewModel(model);
                return View(model);
            }
        }

有人可能会指出我出错的地方我知道我在这里是个菜鸟。

Can someone maybe point out where i went wrong i know im being a noob here.

推荐答案

你可以在这里使用Any（）方法，如： -

You can use Any() method here like:-

bool hasData = db.SIMCards.Any(card => card.ICCID == model.ICCID);
if (hasData ){
  // entity exists in database
}
else {
  // nope, not exists in database
}

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