Dialect needs to be explicitly supplied as of v4.0.0

I have been working on a NodeJS project which uses PostgreSQL database.
I am trying to implement migration to the database. Also, using Sequelize. After setting up the migration folder and config, it throws error while running db:migrate

The error is:
"Dialect needs to be explicitly supplied as of v4.0.0"

did you forget to add the dialect to your config?
see:

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Solution for me was based on what I had set for my `NODE_ENV` variable.

`echo $NODE_ENV`

If you do not have anything set for that variable, try setting it with the following:

`export NODE_ENV=development`

If a value _is_ present, make sure you have an entry in your config file for *that* value. For me, I like to use `local`. So I had to update my config to this:

{
local: {
username: 'root',
password: null,
database: 'database_dev',
host: '127.0.0.1',
dialect: 'postgres'
},
development: {
username: 'root',
password: null,
database: 'database_dev',
host: '127.0.0.1',
dialect: 'postgres'
},
test: {
username: 'root',
password: null,
database: 'database_test',
host: '127.0.0.1',
dialect: 'postgres'
},
production: {
username: 'root',
password: null,
database: 'database',
host: '127.0.0.1',
dialect: 'postgres'
}
}

if you have not setup any .env variables before running your `npm server`

You are likely to get that error. so each time you restart app for changes.
you will have to export again

export DATABASE_URL=<your-db-url>

I got same error and I saw this mistake in the code.

title: {
type: Sequelize,
allowNull: false,
},

Changed my code with this and problem is solved:

title: {
type: Sequelize.STRING,
allowNull: false,
},

My issue was that I wasn't pointing to the config file properly. It said "successfully loaded" but I wasn't pointing to the right file.

It should say "Loaded configuration file "[some path]/config.js"."

Check the dialect once.

```
const Sequelize = require('sequelize');
// Option 1: Passing parameters separately
const sequelize = new Sequelize('database', 'username', 'password', {
host: 'localhost',
dialect: /* one of 'mysql' | 'mariadb' | 'postgres' | 'mssql' */
});
```

This error can also be caused if there is an error in your model schema.

I had:

```
middle_name: {
type: Sequelize.Sequelize,
allowNull: false,
}
```


Which should had been:

```
middle_name: {
type: Sequelize.STRING,
allowNull: false,
}
```

In my case, I declared config.js like as:

module.exports = {
production: {
database: process.env.DB_PROD_DATABASE,
username: process.env.DB_PROD_USERNAME,
password: process.env.DB_PROD_PASSWORD,
options: {
host: process.env.DB_PROD_HOST,
port: process.env.DB_PROD_PORT,
dialect: 'postgres',
define: {
paranoid: true,
timestamp: true,
freezeTableName: true,
underscored: false
}
}
},
development: {
database: process.env.DB_DEV_DATABASE || 'database_name',
username: process.env.DB_DEV_USERNAME || 'user_name',
password: process.env.DB_DEV_PASSWORD || 'pass',
host: process.env.DB_DEV_HOST || 'localhost',
port: process.env.DB_DEV_PORT || 5432,
dialect: 'postgres',
define: {
paranoid: true,
timestamp: true,
freezeTableName: true,
underscored: false
}
}
}

But it should be like as:

module.exports = {
production: {
database: process.env.DB_PROD_DATABASE,
username: process.env.DB_PROD_USERNAME,
password: process.env.DB_PROD_PASSWORD,
options: {
host: process.env.DB_PROD_HOST,
port: process.env.DB_PROD_PORT,
dialect: 'postgres',
define: {
paranoid: true,
timestamp: true,
freezeTableName: true,
underscored: false
}
}
},
development: {
database: 'database_name',
username: 'user_name',
password: 'pass',
host: 'localhost',
port: 5432,
dialect: 'postgres',
define: {
paranoid: true,
timestamp: true,
freezeTableName: true,
underscored: false
}
}
}

without `process.env.DB_DEV_DATABASE || 'database_name'` eg.

I think you have missed **.env file** in your project