go lucene

pergi-lucene

Parser lucene ditulis tanpa ketergantungan.

Dengan paket ini Anda dapat dengan cepat mengintegrasikan pencarian gaya lucene di dalam aplikasi Anda dan menghasilkan filter sql untuk kueri tertentu. Tidak ada ketergantungan eksternal dan tata bahasanya sepenuhnya mendukung Apache Lucene 9.4.2.

Go-lucene langsung mendukung pembuatan sql yang sesuai dengan postgres tetapi dapat diperluas untuk mendukung berbagai jenis sql (atau tanpa sql) juga.

Penggunaan

Gunakan lucene.ToPostgres untuk menghasilkan satu string dengan semua filter Anda di dalamnya.

Gunakan lucene.ToParmeterizedPostgres untuk menghasilkan string berparameter dengan argumen yang dapat Anda teruskan ke kueri DB Anda.

Gunakan opsi lucene.WithDefaultField untuk mengaitkan literal kosong dengan sebuah bidang.

Tali Murni

 // 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;
` 

Masukan yang diparameterisasi

 // 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 )

Bidang Default

 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;
` 

Memperluas dengan driver khusus

Cukup sematkan driver Base di driver khusus Anda dan ganti RenderFN dengan fungsi rendering khusus Anda sendiri.

 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;
	`
}