Loopback ValidationError:"Role"实例无效.详细信息:“名称"已经存在(值:"admin") [英] Loopback ValidationError: The `Role` instance is not valid. Details: `name` already exists (value: "admin")

问题描述

我太新了，无法环回，但是我按照以下步骤在server/boot/内安装并搭建了我的文件夹(环回服务器)，我创建了一个文件script.js，并包含以下代码:

I`m too new to loopback, however i followed the steps to install and scaffold my folder (loopback-server), inside server/boot/ i created one file script.js and included the following code:

    module.exports = function(app) {
var MongoDB = app.dataSources.MongoDB;

MongoDB.automigrate('Customer', function(err) {
   if (err) throw (err);
   var Customer = app.models.Customer;

   Customer.create([
    {username: 'admin', email: '[e-mail]', password: 'abcdef'},
    {username: 'user', email: '[e-mail]', password: 'abcdef'}
  ], function(err, users) {
    if (err) throw (err);
     var Role = app.models.Role;
    var RoleMapping = app.models.RoleMapping;

    //create the admin role
    Role.create({
      name: 'admin'
    }, function(err, role) {
      if (err) throw (err);
       //make admin
      role.principals.create({
        principalType: RoleMapping.USER,
        principalId: users[0].id
      }, function(err, principal) {
        if (err) throw (err);
      });
    });
  });
});

};

现在我收到此错误:

now im getting this error:

如果您需要更多文件，请在下面的评论中让我知道，但我对此文件进行了评论，但未收到该错误. 顺便说一句，我试图更改{username:'admin'，..}和Role.create({ 名称:"admin"}，.... 但是，要么不起作用，要么它起作用，但是我不能以管理员身份登录.对我来说，这太令人困惑了. 有人可以帮忙吗?

if you require more files let me know in comments below please, but i commented this file out and didnt get that error. by the way, i tried to change the keys and values of {username: 'admin',..} and Role.create({ name: 'admin'},.... but either doesnt work or it works but i cant login as admin.. it is too confusing for me. anybody can help please?

谢谢.

推荐答案

如果您将Role实体存储在数据库中，则此代码将尝试创建该Role实体(名称为"admin")每次您的应用程序启动时.但是，在第一次使用该角色后，该角色将已经存在，因此您将收到一个错误，指出您有一个重复的名称".您可能想要做的是检查角色是否不存在，或不将角色存储在数据库中.

If you're Role entity is being stored in a database then this code would try to create that Role entity (with a name of "admin") each time your application starts. However, after the first time, that Role would already exist, thus you get an error that you have a duplicate "name". What you might want to do is check that the Role does not already exist, or not store the Roles in your DB.

您可以添加一些代码来检查当前数据库，并仅在该角色不存在时添加该角色.像这样:

You could add some code to check the current DB and only add that Role if it doesn't exist. Something like this:

Role.find({ name: 'admin' }, function(err, results) {
    if (err) { /* handle this! */ }

    if (results.length < 1) {
        // now we know the DB doesn't have it already, so do the Role creation...
    }
});

请注意，您还需要检查角色"表是否已经具有要添加的主体，并且仅在它们不存在时才添加它们.

Note that you would also want to check if that Role table already has the principals you're adding and only add them if they aren't already there.

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