怎么防止下拉列表控件的EditvalueChanged事件进入死循环

本篇内容主要讲解"怎么防止下拉列表控件的EditvalueChanged事件进入死循环"，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习"怎么防止下拉列表控件的EditvalueChanged事件进入死循环"吧!

当 下拉列表控件选中后判定另一个为空，return之前需要将该下拉列表清空，就又会触发Changed事件，解决方案就是将空值的判断放置最外层，代码如下：

 private void gluCOATemplate_EditValueChanged(object sender, EventArgs e)        {            try            {                if (gluCOATemplate.Text != "")                {                    string sCoaId = gluCOATemplate.Text;                    string sBacthId = txtLotID.Text;                    if (txtLotID.Text == "")                    {                        CommonFunction.ShowMsgBox("检查批号不能为空");                        InitgdvCoaItem();                        gluCOATemplate.Text = "";                        txtLotID.Focus();                        return;                    }                    if (gluCOATemplate.Text == "")                    {                        CommonFunction.ShowMsgBox("请选择模板ID");                        gluCOATemplate.Focus();                        return;                    }                    if (txtLotID.Text != "" && sCoaId != "")                    {                        DataTable dt = new DataTable();                        dt = QCMLIST.QCM_View_COA_Detail(sCoaId, sBacthId);                        if (dt != null)                        {                            udcGVNewDelCtrl1.RecordCount = dt.Rows.Count;                            //DevGridControlHelper.BindData(gdcCOAItem, dt);                            DevGridControlHelper.BindData(gdcCOAItem, dt, new int[] { 1, 1, 1, 1, 1, 1 });                        }                        else                        {                            InitgdvCoaItem();                        }                    }                }            }            catch (Exception ex)            {                CommonFunction.ShowMsgBox(ex.Message);                return;            }        }

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防止添加的数据主键冲突：

一开始没有主键就取查到的最大值+1，

int iSeq = InTag.coa_list[i].item_seq;                            if (iSeq == 0)//传入的Seq为空（0）时，取数据库中最大的+1，否则直接保存                            {                                List uQcmcoaitemlist = ctx.UQcmcoaitem.Where(t => t.PkgNoticeNo == sPkgId && t.Factory == sFactory).OrderByDescending(t=>t.ItemSeq).ToList();                                if (uQcmcoaitemlist != null)                                {                                    iSeq = uQcmcoaitemlist[0].ItemSeq + 1;                                }                                else                                {                                    iSeq = 1;                                }                            }                            UQcmcoaitem uQcmcoaItem = new UQcmcoaitem                            {                                PkgNoticeNo = sPkgId,                                Factory = sFactory,                                ItemSeq = iSeq,                                TestingResult =InTag.coa_list[i].testing_result,                                TestingItem = InTag.coa_list[i].testing_item,                                TestingSpec = InTag.coa_list[i].testing_specification,                                TestingMethod = InTag.coa_list[i].testing_method,                                Dimens = InTag.coa_list[i].dimens,                                CreateTime = DBGV._dbc.DB_GetSysTime(),                                CreateUserId = InTag._cmn_in._user_id                            };                            ctx.UQcmcoaitem.Add(uQcmcoaItem);

但是当添加多条Seq=0的数据时，从数据库查出的最大值+1就会使得要添加的这几天数据的主键冲突，因为事务还没提交，Seq都是Max+1

解决方法：在循环外面加一个int变量（count=0），每次Max+1后，再加上count：

 int count = 0;for (int i = 0; i < InTag.coa_list.Length; i++){                      if (InTag.coa_list[i].step == 'I')                        {                            int iSeq = InTag.coa_list[i].item_seq;                            if (iSeq == 0)                            {                                List uQcmcoaitemlist = ctx.UQcmcoaitem.Where(t => t.PkgNoticeNo == sPkgId && t.Factory == sFactory).OrderByDescending(t=>t.ItemSeq).ToList();                                if (uQcmcoaitemlist != null)                                {                                    iSeq = uQcmcoaitemlist[0].ItemSeq + 1+count;                                    count++;                                }                                else                                {                                    iSeq = 1;                                }                            }                            UQcmcoaitem uQcmcoaItem = new UQcmcoaitem                            {                                PkgNoticeNo = sPkgId,                                Factory = sFactory,                                ItemSeq = iSeq,                                TestingResult =InTag.coa_list[i].testing_result,                                TestingItem = InTag.coa_list[i].testing_item,                                TestingSpec = InTag.coa_list[i].testing_specification,                                TestingMethod = InTag.coa_list[i].testing_method,                                Dimens = InTag.coa_list[i].dimens,                                CreateTime = DBGV._dbc.DB_GetSysTime(),                                CreateUserId = InTag._cmn_in._user_id                            };                            ctx.UQcmcoaitem.Add(uQcmcoaItem);                        }                        else                        {                            sMsgCode = "QCM-0004";                            return GlobalConstant.FAIL;                        }                    }                    ctx.SaveChanges();                    transaction.Commit();

GridLookUpEdit下拉列表的高度设置：

将properties中的AutoHeight设置为false，再设置size的值

到此，相信大家对"怎么防止下拉列表控件的EditvalueChanged事件进入死循环"有了更深的了解，不妨来实际操作一番吧！这里是网站，更多相关内容可以进入相关频道进行查询，关注我们，继续学习！