先说一下场景，产品中用到了简单的表单构造器，开始提供了一系列的控件，例如单行文本框、多行文本框、单选、复选、时间等，之后你可以拖拽控件自己组装你想要的表单……网上有很多的表单构造器，这里就不细说了，可能功能有多有少，但是原理类似。因为这种表单的这种实现方式，我们不单单要存储表单的真实数据，还要存储对应表单的配置数据来渲染表单的样子。这里不细说配置相关的事情，细说一下表单数据的存储和查询。
对于一条记录有很多共有属性：主键ID、创建用户ID、创建时间、表单ID（用于读取表单配置）等一些业务数据，这里着重说一下表单ID也就是下面演示中提到的TableCode,我们这种存储方式可以将业务上的多种表都存储在现在的一张表中，所以必须要一个字段来区分这条记录存储的具体是什么信息，以方便在查询时找到具体的数据；还有一些就是具体的表单项了。我们采用的是Mongodb存储，不用想肯定是复杂结构了，数组或者键值对对象……也不知道什么原因了，我们采用的是数组，这里记作FormItems，FormItems列中存储着所有的表单项，具体的看一下数据库的存储结构：
{ "_id" : "1", "CreateUserName" : "ddz1", "CreateDate" : "2018-02-07", "FormItems" : [ { "key" : "CarBrand", "value" : "红旗" }, { "key" : "VehicleType", "value" : "H7" }, { "key" : "CarNum", "value" : "京A00001" }, { "key" : "PurchaseDate", "value" : "2019-01-01" } ], "TableCode" : "CarInfo" }
上面看到是一个缩减版的结构（为了方便演示），简单的介绍一下：TableCode-表单名称，FormItems数组中存储着所有的表单项，key本来是唯一值，这里仅仅为了演示所以如此，value就是具体的表单项的值了。查询演示用到了三张表，第一张表如上，车辆信息表：车牌子、车型、牌照、购买日期等；车辆维修表：车辆ID、花费、内容；出车记录表：车辆ID、收入、里程、备注。首先插入一些数据：
try{ db.t1.insertMany([{ "_id": "1", "CreateUserName": "ddz1", "CreateDate": "2018-02-07", "FormItems": [{ "key": "CarBrand", "value": "红旗" }, { "key": "VehicleType", "value": "H7" }, { "key": "CarNum", "value": "京A00001" }, { "key": "PurchaseDate", "value": "2019-01-01" }], "TableCode": "CarInfo" },{ "_id": "2", "CreateUserName": "ddz1", "CreateDate": "2018-02-08", "FormItems": [{ "key": "CarBrand", "value": "红旗" }, { "key": "VehicleType", "value": "H5" }, { "key": "CarNum", "value": "京A00002" }, { "key": "PurchaseDate", "value": "2019-02-01" }], "TableCode": "CarInfo" },{ "_id": "3", "CreateUserName": "ddz1", "CreateDate": "2018-02-09", "FormItems": [{ "key": "CarBrand", "value": "红旗" }, { "key": "VehicleType", "value": "L5" }, { "key": "CarNum", "value": "京A00003" }, { "key": "PurchaseDate", "value": "2019-03-01" }], "TableCode": "CarInfo" }, { "_id": "4", "CreateUserName": "ddz1", "CreateDate": "2018-02-10", "FormItems": [{ "key": "CarBrand", "value": "长城" }, { "key": "VehicleType", "value": "哈弗H6" }, { "key": "CarNum", "value": "京A00004" }, { "key": "PurchaseDate", "value": "2018-03-01" }], "TableCode": "CarInfo" },{ "_id": "5", "CreateUserName": "ddz1", "CreateDate": "2018-02-09", "FormItems": [{ "key": "CarBrand", "value": "长城" }, { "key": "VehicleType", "value": "哈弗H5" }, { "key": "CarNum", "value": "京A00005" }, { "key": "PurchaseDate", "value": "2018-03-01" }], "TableCode": "CarInfo" },{ "_id": "6", "CreateUserName": "ddz1", "CreateDate": "2018-03-09", "FormItems": [{ "key": "CarBrand", "value": "长城" }, { "key": "VehicleType", "value": "哈弗H4" }, { "key": "CarNum", "value": "京A00006" }, { "key": "PurchaseDate", "value": "2018-03-01" }], "TableCode": "CarInfo" },{ "_id": "7", "CreateUserName": "ddz100", "CreateDate": "2018-06-06", "FormItems": [{ "key": "CarId", "value": "1" }, { "key": "Cost", "value": 100 }, { "key": "Contents", "value": "喷漆" }], "TableCode": "MaintenanceRecord" },{ "_id": "8", "CreateUserName": "ddz100", "CreateDate": "2018-08-06", "FormItems": [{ "key": "CarId", "value": "1" }, { "key": "Cost", "value": 25 }, { "key": "Contents", "value": "洗车" }], "TableCode": "MaintenanceRecord" },{ "_id": "9", "CreateUserName": "ddz101", "CreateDate": "2018-06-03", "FormItems": [{ "key": "CarId", "value": "2" }, { "key": "Cost", "value": 1560 }, { "key": "Contents", "value": "换轮胎" }], "TableCode": "MaintenanceRecord" },{ "_id": "10", "CreateUserName": "ddz102", "CreateDate": "2018-06-26", "FormItems": [{ "key": "CarId", "value": "3" }, { "key": "Cost", "value": 36 }, { "key": "Contents", "value": "爆胎" }], "TableCode": "MaintenanceRecord" },{ "_id": "11", "CreateUserName": "ddz103", "CreateDate": "2018-09-08", "FormItems": [{ "key": "CarId", "value": "3" }, { "key": "Cost", "value": 1630 }, { "key": "Contents", "value": "换加速器" }], "TableCode": "MaintenanceRecord" },{ "_id": "12", "CreateUserName": "ddz10", "CreateDate": "2018-06-06", "FormItems": [{ "key": "CarId", "value": "1" }, { "key": "Income", "value": 106 }, { "key": "Mileage", "value": 50 }, { "key": "Remarks", "value": "123" }], "TableCode": "DispatchRecord" },{ "_id": "13", "CreateUserName": "ddz11", "CreateDate": "2018-06-16", "FormItems": [{ "key": "CarId", "value": "1" }, { "key": "Income", "value": 250 }, { "key": "Mileage", "value": 100 }, { "key": "Remarks", "value": "123" }], "TableCode": "DispatchRecord" },{ "_id": "14", "CreateUserName": "ddz12", "CreateDate": "2018-06-16", "FormItems": [{ "key": "CarId", "value": "2" }, { "key": "Income", "value": 1000 }, { "key": "Mileage", "value": 630 }, { "key": "Remarks", "value": "2345sfgfg" }], "TableCode": "DispatchRecord" },{ "_id": "15", "CreateUserName": "ddz12", "CreateDate": "2018-08-16", "FormItems": [{ "key": "CarId", "value": "3" }, { "key": "Income", "value": 1213 }, { "key": "Mileage", "value": 569 }, { "key": "Remarks", "value": "12asdfasdfasdf3" }], "TableCode": "DispatchRecord" }]); }catch(e){ print(e); }