类型错误:无法读取未定义的属性“地图":具有对象列表的对象 [英] TypeError: Cannot read property 'map' of undefined : object having list of objects

问题描述

我正在尝试使用以下 json 格式映射数据.具有对象列表的对象.

'''{"pki_user_id":1234,"vc_username":null,"vc_password":null,"vc_name":"Muhammad","vc_email":"[e-mail]","b_isreset":false,"b_timeout":0,"_RoleDto":[{"pki_role_id":30019,"vc_rolename":"SuperUser","vc_roledesc":"超级用户","vc_type":null,"i_group":0,"_MenuDto":null},{"pki_role_id":20015,"vc_rolename":"COMADM","vc_roledesc":"能力管理员","vc_type":null,"i_group":0,"_MenuDto":null},{"pki_role_id":2,"vc_rolename":"IT","vc_roledesc":"IT","vc_type":null,"i_group":0,"_MenuDto":null},{"pki_role_id":3,"vc_rolename":"TAA","vc_roledesc":"考勤管理员","vc_type":null,"i_group":0,"_MenuDto":null}]}'''

这是我检索数据的方式:

 {props.LoginDto.vc_email}{props.LoginDto._RoleDto.map((record,i) => (
{record.pki_role_id}
))}

每次我收到这个错误.我使用 react redux 来接收 props 数据.

解决方案

像这样添加一个空检查:

{props.LoginDto &&props.LoginDto.vc_email}{props.LoginDto &&props.LoginDto._RoleDto &&!!props.LoginDto._RoleDto.length &&props.LoginDto._RoleDto.map((record,i) => (
{record.pki_role_id}
))}

I'm trying to map data using below json format. An object having list of objects.

'''{"pki_user_id":1234,"vc_username":null,"vc_password":null,"vc_name":"Muhammad","vc_email":"[e-mail]","b_isreset":false,"b_timeout":0,"_RoleDto":[{"pki_role_id":30019,"vc_rolename":"SuperUser","vc_roledesc":"Super User","vc_type":null,"i_group":0,"_MenuDto":null},{"pki_role_id":20015,"vc_rolename":"COMADM","vc_roledesc":"Competency Admin","vc_type":null,"i_group":0,"_MenuDto":null},{"pki_role_id":2,"vc_rolename":"IT","vc_roledesc":"IT","vc_type":null,"i_group":0,"_MenuDto":null},{"pki_role_id":3,"vc_rolename":"TAA","vc_roledesc":"Time Attendance Administrator","vc_type":null,"i_group":0,"_MenuDto":null}]}'''

This is how I'm retrieving data:

        {props.LoginDto.vc_email}

        {props.LoginDto._RoleDto.map((record,i) => (

          <div key = {i}> {record.pki_role_id}</div>
        ))}

      </div>

Every time I'm getting this error. I'using react redux to receive props data.

解决方案

Add a null check like this:

{props.LoginDto && props.LoginDto.vc_email}

        {props.LoginDto && props.LoginDto._RoleDto && !!props.LoginDto._RoleDto.length && props.LoginDto._RoleDto.map((record,i) => (

          <div key = {i}> {record.pki_role_id}</div>
        ))}

      </div>

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