无法投射物品＆＃39; jxl.biff.EmptyCell@47821b4b'与班级＆＃39; jxl.biff.EmptyCell＆＃39;上课＆＃39; jxl.DateCell＆＃39;

Question

我的域名模型

package sample

class Person {

String lastName
String firstName
Date dateOfBirth
int numberOfChildren
static constraints = {
}
} 

我的控制器

package sample

/*imported libraries.*/

import jxl.DateCell
import jxl.LabelCell
import jxl.NumberCell
import jxl.Sheet
import jxl.Workbook

class PersonController {
private final static int COLUMN_LAST_NAME = 0
private final static int COLUMN_FIRST_NAME = 1
private final static int COLUMN_DATE_OF_BIRTH = 2
private final static int COLUMN_NUMBER_OF_CHILDREN = 3

 def index() {
    redirect(action: "list", params: params)
}

def list(Integer max) {
    params.max = Math.min(max ?: 10, 100)
    [personInstanceList: Person.list(params), personInstanceTotal: Person.count()]
}

def upload() { }


    def doUpload() {
    def file = request.getFile('file')
    Workbook workbook = Workbook.getWorkbook(file.getInputStream());
    Sheet sheet = workbook.getSheet(0);

    // skip first row (row 0) by starting from 1
    for (int row = 1; row < sheet.getRows(); row++) {
        LabelCell lastName = sheet.getCell(COLUMN_LAST_NAME, row)
        LabelCell firstName = sheet.getCell(COLUMN_FIRST_NAME, row)
        DateCell dateOfBirth = sheet.getCell(COLUMN_DATE_OF_BIRTH, row)
        NumberCell numberOfChildren = sheet.getCell(COLUMN_NUMBER_OF_CHILDREN, row)

        new Person(lastName:lastName.string , firstName:firstName.string ,
                dateOfBirth:dateOfBirth.date, numberOfChildren:numberOfChildren.value).save()

    }
    redirect (action:'list')
}


} 

我想从我的grails数据库中的.xls文件加载数据，问题是xls文件加载数据没有保存，我得到以下错误。     无法投射物品＆＃39; jxl.biff.EmptyCell@47821b4b'与班级＆＃39; jxl.biff.EmptyCell＆＃39;上课＆＃39; jxl.DateCell＆＃39;。

Answer 1

看起来，在某些情况下，dateOfBirth没有任何价值。在这些情况下，空值无法转换为日期。这就是抛出can not cast class 'jxl.biff.EmptyCell' to class 'jxl.DateCell'的原因。

当dateOfBirth单元格为空时，请确保将null设置为dataOfBirth。如果您对dateOfBirth字段有约束，它将自动抛出exception。

空constraints表示Person类中的所有属性都是必需的。显然Excel表格中有空字段会导致整个过程停止。如果您仍然希望忽略那些具有空字段且仍处理好字段的行，则可以执行以下一项或两项操作：

检查每个字段是否为空，并调用继续处理下一行。这是我的建议。

和/或

使用try / catch：

包裹循环内部

    for (int row = 1; row < sheet.getRows(); row++) {
        try{
                LabelCell lastName = sheet.getCell(COLUMN_LAST_NAME, row)
                LabelCell firstName = sheet.getCell(COLUMN_FIRST_NAME, row)
                DateCell dateOfBirth = sheet.getCell(COLUMN_DATE_OF_BIRTH, row)
                NumberCell numberOfChildren = sheet.getCell(COLUMN_NUMBER_OF_CHILDREN, row)
new Person(lastName:lastName.string , firstName:firstName.string ,
                        dateOfBirth:dateOfBirth.date, numberOfChildren:numberOfChildren.value).save(failOnError: true)
        }catch(e){
          // log the error and the row number so that you know which row failed
        }

    }

要更好地了解哪个字段验证失败，请编写正确的字段验证错误消息。