# Testing a Database

You can study about databases, SQL, and SQLModel in the <a href="https://sqlmodel.tiangolo.com/" class="external-link" target="_blank">SQLModel docs</a>. 🤓

There's a mini <a href="https://sqlmodel.tiangolo.com/tutorial/fastapi/" class="external-link" target="_blank">tutorial on using SQLModel with FastAPI</a>. ✨

Guilherme Rameh <******@****.***> 1729253044 -0300

	Username           string    `json:"username"` // default: user running minio
	Password           string    `json:"password"` // default: no password
	Database           string    `json:"database"` // default: same as user
	QueueDir           string    `json:"queueDir"`
	QueueLimit         uint64    `json:"queueLimit"`
	MaxOpenConnections int       `json:"maxOpenConnections"`
}

	sqlserverDSN = "sqlserver://sa:LoremIpsum86@localhost:9930?database=master"
	tidbDSN      = "root:@tcp(localhost:9940)/test?charset=utf8&parseTime=True&loc=Local"
)

func init() {
	var err error
	if DB, err = OpenTestConnection(&gorm.Config{}); err != nil {
		log.Printf("failed to connect database, got error %v", err)
		os.Exit(1)
	} else {
		sqlDB, err := DB.DB()
		if err != nil {

    - 🧰 [SQLModel](https://sqlmodel.tiangolo.com) for the Python SQL database interactions (ORM).
    - 🔍 [Pydantic](https://docs.pydantic.dev), used by FastAPI, for the data validation and settings management.
    - 💾 [PostgreSQL](https://www.postgresql.org) as the SQL database.
- 🚀 [React](https://react.dev) for the frontend.

	Host               xnet.URL `json:"host"`
	Port               string   `json:"port"`
	User               string   `json:"user"`
	Password           string   `json:"password"`
	Database           string   `json:"database"`
	QueueDir           string   `json:"queueDir"`
	QueueLimit         uint64   `json:"queueLimit"`
	MaxOpenConnections int      `json:"maxOpenConnections"`
}

// Validate MySQLArgs fields

For example, if you need to store it in a database.

For that, **FastAPI** provides a `jsonable_encoder()` function.

## Using the `jsonable_encoder`

Let's imagine that you have a database `fake_db` that only receives JSON compatible data.

For example, it doesn't receive `datetime` objects, as those are not compatible with JSON.

    By having the type as `int | None`, SQLModel will know that this column should be an `INTEGER` in the SQL database and that it should be `NULLABLE`.

* `Field(index=True)` tells SQLModel that it should create a **SQL index** for this column, that would allow faster lookups in the database when reading data filtered by this column.

// for example: one goroutine found error and just close the database, and others are executing SQL
// this test making sure that the gorm would not get a Segmentation Fault,
// and the only error cause by this is using a closed Stmt or gorm.ErrInvalidDB
// and all of the goroutine must got gorm.ErrInvalidDB after database close
func TestPreparedStmtConcurrentClose(t *testing.T) {

use internally only data that doesn't depend on the resources of dependencies with `yield`.

For example, instead of using the same database session, you would create a new database session inside of the background task, and you would obtain the objects from the database using this new session. And then instead of passing the object from the database as a parameter to the background task function, you would pass the ID of that object and then obtain the object again inside the background...