Node.js 用 mysql 编写 api 代码（续集）答案

【问题标题】：Node.js writing api code with mysql(sequelize)Node.js 用 mysql 编写 api 代码（续集）
【发布时间】：2018-06-03 19:51:20
【问题描述】：

我的mysql表模型：

//mysql
//table structures start

var Contact = sequelize.define('contact', {
    gsm: {
        type: Sequelize.STRING,
        unique: true,
        required: true
    },
    firstName: Sequelize.STRING,
    lastName: Sequelize.STRING,
    street: Sequelize.STRING,
    city: Sequelize.STRING,
})

var Group = sequelize.define('group', {
    groupname: Sequelize.STRING

})

var ContactGroup = sequelize.define('contactgroup', {
    /* Empty */
})

ContactGroup.belongsTo(Contact, {
    onDelete: 'CASCADE'
});

Contact.hasMany(ContactGroup, {
    onDelete: 'CASCADE'
});

ContactGroup.belongsTo(Group, {
    onDelete: 'CASCADE'
});
Group.hasMany(ContactGroup, {
    onDelete: 'CASCADE'
});

这是我的第一个 api 代码：

exports.getNewGroup = (req, res) => {
    Group.findAll({
        attributes: ['id', 'groupname', [sequelize.fn('COUNT', sequelize.col('contactgroups.groupId')), 'contactsCount']],
        include: [{
            model: ContactGroup,
            attributes: ['id']
        }],
        group: ['id']
    }).then(data => {
        return res.status(200).send(data);
    }).catch(err => {
        return res.status(400).send(err.message);
    });
};

我得到了第一个这样的 api 响应：

[
    {
        "id": 14,
        "groupname": "Angular",
        "contactsCount": 2,
        "contactgroups": [
            {
                "id": 1
            }
        ]
    },
    {
        "id": 15,
        "groupname": "React",
        "contactsCount": 1,
        "contactgroups": [
            {
                "id": 3
            }
        ]
    },
    {
        "id": 16,
        "groupname": "Vue",
        "contactsCount": 0,
        "contactgroups": []
    },
    {
        "id": 17,
        "groupname": "NodeJs",
        "contactsCount": 0,
        "contactgroups": []
    },
    {
        "id": 18,
        "groupname": "RxJS",
        "contactsCount": 0,
        "contactgroups": []
    }
]

这是我的第二个 api 代码：

exports.getNewGroupForProfsms = (req, res) => {
    Group.findAll({
        include: [{
            model: ContactGroup,
            attributes: ['id'],
            include: [{
                model: Contact,
                attributes: ['id', 'gsm']
            }]
        }],
    }).then(data => {
        return res.status(200).send(data);
    }).catch(err => {
        return res.status(400).send(err.message);
    });
};

这是我的第二个 api 响应：

[
    {
        "id": 14,
        "groupname": "Angular",
        "createdAt": "2017-12-15T15:06:39.000Z",
        "updatedAt": "2017-12-15T15:06:39.000Z",
        "contactgroups": [
            {
                "id": 1,
                "contact": {
                    "id": 20,
                    "gsm": "987654321"
                }
            },
            {
                "id": 2,
                "contact": {
                    "id": 21,
                    "gsm": "123456789"
                }
            }
        ]
    },
    {
        "id": 15,
        "groupname": "React",
        "createdAt": "2017-12-15T15:06:45.000Z",
        "updatedAt": "2017-12-15T15:06:45.000Z",
        "contactgroups": [
            {
                "id": 3,
                "contact": {
                    "id": 21,
                    "gsm": "123456789"
                }
            }
        ]
    },
    {
        "id": 16,
        "groupname": "Vue",
        "createdAt": "2017-12-15T15:06:51.000Z",
        "updatedAt": "2017-12-15T15:06:51.000Z",
        "contactgroups": []
    },
    {
        "id": 17,
        "groupname": "NodeJs",
        "createdAt": "2017-12-17T16:07:38.000Z",
        "updatedAt": "2017-12-17T16:07:38.000Z",
        "contactgroups": []
    },
    {
        "id": 18,
        "groupname": "RxJS",
        "createdAt": "2017-12-21T05:50:50.000Z",
        "updatedAt": "2017-12-21T05:50:50.000Z",
        "contactgroups": []
    }
]

在上面的代码中，我写了两个api，现在我想写一个api，

我需要这种类型的响应：（我在第一个 api 响应中有 contactsCount，我希望在第二个 api 响应中使用）

最后我想要这种类型的响应与单个 api 代码：

[
    {
        "id": 14,
        "groupname": "Angular",
        "contactsCount": 2,
        "createdAt": "2017-12-15T15:06:39.000Z",
        "updatedAt": "2017-12-15T15:06:39.000Z",
        "contactgroups": [
            {
                "id": 1,
                "contact": {
                    "id": 20,
                    "gsm": "987654321"
                }
            },
            {
                "id": 2,
                "contact": {
                    "id": 21,
                    "gsm": "123456789"
                }
            }
        ]
    },
    {
        "id": 15,
        "groupname": "React",
        "contactsCount": 1,
        "createdAt": "2017-12-15T15:06:45.000Z",
        "updatedAt": "2017-12-15T15:06:45.000Z",
        "contactgroups": [
            {
                "id": 3,
                "contact": {
                    "id": 21,
                    "gsm": "123456789"
                }
            }
        ]
    },
    {
        "id": 16,
        "groupname": "Vue",
        "contactsCount": 0,
        "createdAt": "2017-12-15T15:06:51.000Z",
        "updatedAt": "2017-12-15T15:06:51.000Z",
        "contactgroups": []
    },
    {
        "id": 17,
        "groupname": "NodeJs",
        "contactsCount": 0,
        "createdAt": "2017-12-17T16:07:38.000Z",
        "updatedAt": "2017-12-17T16:07:38.000Z",
        "contactgroups": []
    },
    {
        "id": 18,
        "groupname": "RxJS",
        "contactsCount": 0,
        "createdAt": "2017-12-21T05:50:50.000Z",
        "updatedAt": "2017-12-21T05:50:50.000Z",
        "contactgroups": []
    }
]

有人会帮助我吗？我需要单个 api 代码。

我尝试了嵌套查询，并像这样修改了我的第一个 api 代码：

exports.getNewGroup = (req, res) => {
    Group.findAll({
        attributes: ['id', 'groupname', [sequelize.fn('COUNT', sequelize.col('contactgroups.groupId')), 'contactsCount']],
        include: [{
            model: ContactGroup,
            attributes: ['id'],
            include: [{
                model: Contact,
                attributes: ['id', 'gsm']
            }]
        }],
        group: ['id']
    }).then(data => {
        return res.status(200).send(data);
    }).catch(err => {
        return res.status(400).send(err.message);
    });
};

但我得到了这种类型的回应不是我的要求

[
    {
        "id": 14,
        "groupname": "Angular",
        "contactsCount": 2,
        "contactgroups": [
            {
                "id": 1,
                "contact": {
                    "id": 20,
                    "gsm": "987654321"
                }
            }
        ]
    },
    {
        "id": 15,
        "groupname": "React",
        "contactsCount": 1,
        "contactgroups": [
            {
                "id": 3,
                "contact": {
                    "id": 21,
                    "gsm": "123456789"
                }
            }
        ]
    },
    {
        "id": 16,
        "groupname": "Vue",
        "contactsCount": 0,
        "contactgroups": []
    },
    {
        "id": 17,
        "groupname": "NodeJs",
        "contactsCount": 0,
        "contactgroups": []
    },
    {
        "id": 18,
        "groupname": "RxJS",
        "contactsCount": 0,
        "contactgroups": []
    }
]

【问题讨论】：

你可以在第一个api中嵌套查询组，或者在你的sql中使用right join，但是为了更好的性能和设计，请参考docs.sequelizejs.com/manual/tutorial/…
你能发布一些代码吗？如果我在我的第一个 api 中嵌套查询，我没有得到正确的响应，等待我将发布我尝试过的嵌套查询代码。
@JoshLin 查看我更新的问题，我编写了嵌套包含代码。
您只希望在第二个 API 中使用 contactsCount？类似res.send(data.map((x)=>{...x,contactsCount:x.contactgroups.length}))?
@JoshLin 我是 nodejs 的新手，我可以在哪里发布此代码？是的，我只需要联系人数，你能发布一些答案吗？

标签： mysql json node.js api sequelize.js

【解决方案1】：

试试这个代码

exports.getNewGroupForProfsms = (req, res) => {
  Group.findAll({
    include: [{
      model: ContactGroup,
      attributes: ['id'],
      include: [{
        model: Contact,
        attributes: ['id', 'gsm']
      }]
    }],
  }).then(data => {
    // change happen here
    return res.status(200).send(data.map((x) => {
      // assign contactsCount to each row
      return Object.assign({
        contactsCount: x.contactgroups.length,
      }, x.toJSON()) // update toJSON have a try
    }));
  }).catch(err => {
    return res.status(400).send(err.message);
  });
};

【讨论】：

不工作，我的回复中仍然没有contactCount
我在exports.getnewgroup api中有contactCount。
我的回复仍然像hastebin.com/irahimuluw.json :) 我没有得到contactCount
Object.assign({ contactsCount: x.contactgroups.length, }, x) 分配给新对象，如果仍然无法正常工作，请使用 .send(data.map(()=>'aaa')) 检查响应是否更改
我使用 .send(data.map(()=>'aaa')) 进行了检查。我得到了 [“aaa”、“aaa”、“aaa”、“aaa”、“aaa”]