go lucene

go-lucene

Un analizador lucene escrito en go sin dependencias.

Con este paquete, puede integrar rápidamente la búsqueda de estilo lucene dentro de su aplicación y generar filtros SQL para una consulta en particular. No hay dependencias externas y la gramática es totalmente compatible con Apache Lucene 9.4.2.

Go-lucene listo para usar admite la generación de SQL compatible con Postgres, pero también se puede ampliar para admitir diferentes tipos de SQL (o no SQL).

Uso

Utilice lucene.ToPostgres para generar una sola cadena con todos sus filtros.

Utilice lucene.ToParmeterizedPostgres para generar una cadena parametrizada con argumentos que pueda pasar a su consulta de base de datos.

Utilice la opción lucene.WithDefaultField para asociar literales simples con un campo.

Cuerda pura

 // suppose you want a query for red apples that are not honey crisp or granny smith and are older than 5 months old
myQuery := `color:red AND NOT (type:"honey crisp" OR type:"granny smith") AND age_in_months:[5 TO *]`
filter , err := lucene . ToPostgres ( myQuery )
if err != nil {
    // handle error
}

SQLTemplate := `
SELECT *
FROM apples
WHERE %s
LIMIT 10;
`
sqlQuery := fmt . Sprintf ( SQLTemplate , filter )

// sqlQuery is:
`

SELECT *
FROM apples
WHERE
    (
		("color" = 'red') AND 
		(
			NOT(
				("type" = 'honey crisp') OR 
				("type" = 'granny smith')
			)
		)
	) AND 
	("age_in_months" >= 5)
LIMIT 10;
` 

Entrada parametrizada

 // suppose you want a query for red apples that are not honey crisp or granny smith and are older than 5 months old
myQuery := `color:red AND NOT (type:"honey crisp" OR type:"granny smith") AND age_in_months:[5 TO *]`
filter , params , err := lucene . ToParameterizedPostgres ( myQuery )
if err != nil {
    // handle error
}

SQLTemplate := `
SELECT *
FROM apples
WHERE %s
LIMIT 10;
`
sqlQuery := fmt . Sprintf ( SQLTemplate , filter )

db . Query ( sqlQuery , params )

Campos predeterminados

 myQuery := "red OR green"
filter , err := lucene . ToPostgres (
	myQuery , lucene . WithDefaultField ( "appleColor" ))
if err != nil {
    // handle error
}

SQLTemplate := `
SELECT *
FROM apples
WHERE %s
LIMIT 10;
`
sqlQuery := fmt . Sprintf ( SQLTemplate , filter )

// sqlQuery is:
`
SELECT *
FROM apples
WHERE
    ("appleColor" = 'red') OR ("appleColor" = 'green')
LIMIT 10;
` 

Ampliando con un controlador personalizado

Simplemente incruste el controlador Base en su controlador personalizado y anule RenderFN con sus propias funciones de renderizado personalizadas.

 import (
	"github.com/grindlemire/go-lucene"
	"github.com/grindlemire/go-lucene/pkg/driver"
	"github.com/grindlemire/go-lucene/pkg/lucene/expr"
)

type MyDriver struct {
	driver. Base
}
// Suppose we want a customer driver that is postgres but uses "==" rather than "=" for an equality check.
func NewMyDriver () MyDriver {
	// register your new custom render functions. Each render function
	// takes a left and optionally right rendered string and returns the rendered
	// output string for the entire expression.
	fns := map [expr. Operator ]driver. RenderFN {
		expr . Equals : myEquals ,
	}

	// iterate over the existing base render functions and swap out any that you want to
	for op , sharedFN := range driver . Shared {
		_ , found := fns [ op ]
		if ! found {
			fns [ op ] = sharedFN
		}
	}

	// return the new driver ready to use
	return MyDriver {
		driver. Base {
			RenderFNs : fns ,
		},
	}
}

// Suppose we wanted to implement equals using a "==" operator instead of "="
func myEquals ( left , right string ) ( string , error ) {
	return left + " == " + right , nil
}

...
func main () {
	// create a new instance of the driver
	driver := NewMyDriver ()

	// render an expression
	expr , _ := lucene . Parse ( `color:red AND NOT (type:"honey crisp" OR type:"granny smith") AND age_in_months:[5 TO *]` )
	filter , _ := driver . Render ( expr )
	
	SQLTemplate := `
	SELECT *
	FROM apples
	WHERE %s
	LIMIT 10;
	`
	sqlQuery := fmt . Sprintf ( SQLTemplate , filter )

	// sqlQuery is:
	`

	SELECT *
	FROM apples
	WHERE
		(
			("color" == 'red') AND 
			(
				NOT(
					("type" == 'honey crisp') OR 
					("type" == 'granny smith')
				)
			)
		) AND 
		("age_in_months" >= 5)
	LIMIT 10;
	`
}