This is very useful when you need to:

* Have shared logic (the same code logic again and again).
* Share database connections.
* Enforce security, authentication, role requirements, etc.
* And many other things...

All these, while minimizing code repetition.

## First Steps { #first-steps }

    This is used internally by FastAPI to make sure anything you return can be
    encoded as JSON before it is sent to the client.

    You can also use it yourself, for example to convert objects before saving them
    in a database that supports only JSON.

    Read more about it in the
    [FastAPI docs for JSON Compatible Encoder](https://fastapi.tiangolo.com/tutorial/encoder/).
    """
    custom_encoder = custom_encoder or {}

### Multiple Applications { #multiple-applications }

In the same server (or servers), there could be **multiple applications**, for example, other API programs or a database.

package gorm

import (
	"context"
	"database/sql"
	"database/sql/driver"
	"fmt"
	"reflect"
	"regexp"
	"sort"
	"strconv"
	"strings"
	"sync"

	"gorm.io/gorm/clause"
	"gorm.io/gorm/logger"
	"gorm.io/gorm/schema"
	"gorm.io/gorm/utils"
)

// Statement statement
type Statement struct {
	*DB
	TableExpr            *clause.Expr
	Table                string
	Model                interface{}

 - [Confluence/Jira](https://github.com/codelibs/fess-ds-atlassian)
 - [Box](https://github.com/codelibs/fess-ds-box)
 - [CSV](https://github.com/codelibs/fess-ds-csv)
 - [Database](https://github.com/codelibs/fess-ds-db)
 - [Dropbox](https://github.com/codelibs/fess-ds-dropbox)
 - [Elasticsearch](https://github.com/codelibs/fess-ds-elasticsearch)
 - [Git](https://github.com/codelibs/fess-ds-git)

    @Resource
    private SessionManager sessionManager;

    /** The Fess configuration providing application settings. */
    @Resource
    private FessConfig fessConfig;

    /** The user behavior for database operations on user entities. */
    @Resource
    private UserBhv userBhv;

    // ===================================================================================

    //                                                                      ==============
    /**
     * Creates a new access context arranger for database operations.
     * This method provides a dummy implementation as Fess does not use DBFlute extensively.
     *
     * @return a new access context arranger
     */
    @Override

				db.AddError(err)
			}
			return
		}

		// append @id column with value for auto-increment primary key
		// the @id value is correct, when: 1. without setting auto-increment primary key, 2. database AutoIncrementIncrement = 1
		switch values := db.Statement.Dest.(type) {
		case map[string]interface{}:
			values[pkFieldName] = insertID
		case *map[string]interface{}:
			(*values)[pkFieldName] = insertID

every item inside and make sure it is serializable as JSON, using the same [JSON Compatible Encoder](../tutorial/encoder.md){.internal-link target=_blank} explained in the tutorial. This is what allows you to return **arbitrary objects**, for example database models.

But if you are certain that the content that you are returning is **serializable with JSON**, you can pass it directly to the response class and avoid the extra overhead that FastAPI would have by passing your return content through...

{* ../../docs_src/sql_databases/tutorial001_an_py310.py ln[25:30] hl[25:27,30] *}

### Criar Tabelas de Banco de Dados na Inicialização { #create-database-tables-on-startup }

Vamos criar as tabelas do banco de dados quando o aplicativo for iniciado.

{* ../../docs_src/sql_databases/tutorial001_an_py310.py ln[32:37] hl[35:37] *}