Sequelize - 在关联表上选择

Question

我的问题：

我正在创建一条路线，它将返回有关组的一些信息，它有一个 id、一个分配的用户并且还有一些文档。我只是想显示存在多少文档，在 SQL 中将是 SELECT COUNT，但是我如何在 sequelize 中做到这一点？

我的代码：

async list(req, res){
        const docGroups = await DocGroup.findAll({
            raw: true,
            include: [{
                  model: User,
                  as: 'userAssigned'
               },
               {
                  model: Document,
                  as: 'Document'
               }
            ]
        }).then(groups => {
            const result = groups.map(group => {
                return Object.assign(
                    {},
                    {
                        id: group.id,
                        name: group.name,
                        userAssinged: group['userAssigned.firstName'],
                        docAmount: // I want to put documents' count here

                    }   
                )

            })
            console.log(groups)    
        })
    }

console.log(groups) 中打印的内容：

[
  {
    id: 1,
    name: 'pleaseworks',
    createdAt: 2020-06-10T02:38:11.531Z,
    updatedAt: 2020-06-10T02:38:11.531Z,
    'userAssigned.id': 1,
    'userAssigned.firstName': 'Please',
    'userAssigned.lastName': 'Works',
    'userAssigned.email': 'pleaseworks@gmail.com',
    'userAssigned.password': '$2a$08$3BA4I4dsaQ3lsHy342344b5P41v5eHWjwqv6dve28nSdqbGvhsdS',
    'userAssigned.createdAt': 2020-06-10T02:37:29.062Z,
    'userAssigned.updatedAt': 2020-06-10T02:37:29.062Z,
    'userAssigned.groupId': null,
    'Document.id': 2,
    'Document.description': 'deowkdopewkdwe',
    'Document.content': 'odepodkewokodwe',
    'Document.groupId': 1,
    'Document.createdAt': 2020-06-10T02:43:46.005Z,
    'Document.updatedAt': 2020-06-10T02:43:46.005Z
  }
]

Answer 1

如果DocGroup 有很多Document，试试这样：

{
  model: Document,
  attributes: [[sequelize.fn('COUNT', sequelize.col('id')), 'docAmount']]
  as: 'Document'
}