symfony 3.4服务别名

Question

我试试这段代码

mea_memento.datatables.correspondence_datatable:
    alias: Mea\MementoBundle\Datatables\CorrespondenceDatatable
    class: Mea\MementoBundle\Datatables\CorrespondenceDatatable
    parent: sg_datatables.datatable.abstract

尝试获取CorrespondenceDatatable :: class - 找不到服务 我无法设置新的命名 -

Mea\MementoBundle\CorrespondenceDatatable:
    parent: sg_datatables.datatable.abstract

Service definition "Mea\MementoBundle\CorrespondenceDatatable" has a parent but no class, and its name looks like a FQCN. Either the class is missing or you want to inherit it from the parent service. To resolve this ambiguity, please rename this service to a non-FQCN (e.g. using dots), or create the missing class.