> For the complete documentation index, see [llms.txt](https://shoppinpal.gitbook.io/docs-shoppinpal-com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://shoppinpal.gitbook.io/docs-shoppinpal-com/3.-the-backend/understanding-usermodel.md).

# Understanding UserModel

You should see two new files:

```
$ cd ~/workspace/loopback-zero-to-hero  
$ tree common -L 3
common
└── models
    ├── user-model.js
    └── user-model.json

1 directory, 2 files
```

Take note of the following: a) `user-model.json` has the following lines:

```
  "name": "UserModel",
  "base": "User",
```

b) the files are named `user-model.js` and `user-model.json` but the internal name used by code is `UserModel`, this is part of loopback's naming convention.

c) `user-model.json` serves as a configurable entry point whereas `user-model.js` lets you add code when something more specialized may be required, something that can't be simply configured.

d) Moving forward we will always use `UserModel` so we can and should hide the `User` model from the prying eyes of our REST\~ful api.

e) The `server/model-config.json` file is the gatekeeper for what's exposed over REST and what's not.

```
cat ~/workspace/loopback-zero-to-hero/server/model-config.json
{
  ...
  "User": {
    "dataSource": "db"
  },
  ...
  "UserModel": {
    "dataSource": "db",
    "public": true
  }
}
```

f) Go ahead and set `"public": false` for `User` in `model-config.json` file:

```
{
  ...
  "User": {
    "dataSource": "db",
    "public": false
  },
  ...
}
```

g) Fire up the server:

```
$ cd ~/workspace/loopback-zero-to-hero
$ node .
Browse your REST API at http://0.0.0.0:3000/explorer
Web server listening at: http://0.0.0.0:3000/
```

h) `Project > Box Info`

i) Open a browser window: `http://<box-name>.codio.io:3000/explorer/`

j) The `UserModel` api will be ready to explore and `User` will be no more!

k) Use `/POST UserModels` from the explorer UI to create a user:

```
    {
      "username": "test",
      "password": "test",
      "email": "test@test.com"
    }
```

```
Use that as the json body and then click the `Try it out!` button.
```

```
l) There is a distinct possiblility that your server will crash at this point with `TypeError: Object.keys called on non-object`

Here's the full sample stack trace:
```

events.js:72 throw er; // Unhandled 'error' event ^ TypeError: Object.keys called on non-object at Function.keys (native) at Memory.all (/home/codio/workspace/loopback-zero-to-hero/node\_modules/loopback-datasource-juggler/lib/connectors/memory.js:315:22) at /home/codio/workspace/loopback-zero-to-hero/node\_modules/loopback-datasource-juggler/lib/dao.js:1453:19 at doNotify (/home/codio/workspace/loopback-zero-to-hero/node\_modules/loopback-datasource-juggler/lib/observer.js:93:49) at doNotify (/home/codio/workspace/loopback-zero-to-hero/node\_modules/loopback-datasource-juggler/lib/observer.js:93:49) at doNotify (/home/codio/workspace/loopback-zero-to-hero/node\_modules/loopback-datasource-juggler/lib/observer.js:93:49) at doNotify (/home/codio/workspace/loopback-zero-to-hero/node\_modules/loopback-datasource-juggler/lib/observer.js:93:49) at doNotify (/home/codio/workspace/loopback-zero-to-hero/node\_modules/loopback-datasource-juggler/lib/observer.js:93:49) at Function.ObserverMixin.\_notifyBaseObservers (/home/codio/workspace/loopback-zero-to-hero/node\_modules/loopback-datasource-juggler/lib/observer.js:116:5) at Function.ObserverMixin.notifyObserversOf (/home/codio/workspace/loopback-zero-to-hero/node\_modules/loopback-datasource-juggler/lib/observer.js:91:8)

```
|||guidance
# Guidance

If this happens, simply delete the previous `db.json` file:
`rm ~/workspace/loopback-zero-to-hero/db.json `
And start the server again, then Follow steps (g) through (k) again.
|||

m) Take a peek at the database, it should have a new UserModel instance: `cat db.json`
```

$ cat db.json { "ids": { "User": 1, "AccessToken": 1, "ACL": 1, "RoleMapping": 1, "Role": 1, "UserModel": 2 }, "models": { "User": {}, "AccessToken": {}, "ACL": {}, "RoleMapping": {}, "Role": {}, "UserModel": { "1": "{\\"username\\":\\"test\\",\\"password\\":\\"$2a$10$DD6l9hEK0YraAvQ9wxXoyujLyted4YUUOUX9opiTUe8RwPOGe8mY2\\",\\"email\\":\\"<test@test.com>\\",\\"id\\":1}" } } }

\`\`\`