Batch results at localhost in raw text format.

examples/batch/batch.go

@@ -4,8 +4,8 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"io"
-	"os"
+	"net/http"
+	"strings"
 
 	pgx "github.com/jackc/pgx/v5"
 	pgconn "github.com/jackc/pgx/v5/pgconn"
@@ -20,48 +20,79 @@ type PgxPoolInterface interface {
 }
 
 type ExampleBatch struct {
-	batch *pgx.Batch
-	br    pgx.BatchResults
-	db    PgxPoolInterface
+	batch  *pgx.Batch
+	br     pgx.BatchResults
+	db     PgxPoolInterface
+	output strings.Builder
+}
+
+func (ex *ExampleBatch) insertRow(fields ...string) (err error) {
+	for i, value := range fields {
+		fields[i] = "$$" + value + "$$"
+	}
+	sql := `INSERT INTO metadata (title, authors, subject, description)
+	VALUES 
+	(` + strings.Join(fields[:4], ", ") + ");"
+	_, err = ex.db.Exec(context.Background(), sql)
+	return err
 }
 
 func (ex *ExampleBatch) databaseSetup() (err error) {
-	// Create a new table 'ledger'
-	sql := `CREATE TABLE IF NOT EXISTS ledger (
-		id BIGINT PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY,
-		description TEXT NOT NULL,
-		amount BIGINT NOT NULL);`
+	// Create a new table 'metadata'
+	sql := `
+	CREATE TABLE IF NOT EXISTS metadata (
+	id BIGINT PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY,
+	title TEXT NOT NULL,
+	authors TEXT NOT NULL,
+	subject TEXT NOT NULL,
+	description TEXT NOT NULL);
+	DELETE FROM metadata ;
+	INSERT INTO metadata (title, authors, subject, description)
+	VALUES
+		($$A Journey Through the Alps$$, $$John Doe, Jane Smith$$, $$Hiking, Nature, Travel$$, $$Explore the breathtaking beauty of the Alps on a scenic hiking adventure. Discover hidden trails, alpine lakes, and charming mountain villages.$$),
+		($$The Art of Baking: A Beginner's Guide$$, $$Emily Baker$$, $$Cooking, Baking, Food$$, $$Learn the fundamentals of baking and create delicious treats from scratch. Master techniques like kneading dough, frosting cakes, and piping cookies.$$),
+		($$The History of Ancient Rome$$, $$David Johnson$$, $$History, Ancient Rome, Civilization$$, $$Delve into the fascinating history of the Roman Empire. Explore its rise to power, its cultural achievements, and its eventual decline.$$);
+	`
 	_, err = ex.db.Exec(context.Background(), sql)
 	return err
 }
 
-func (ex *ExampleBatch) printResults(file io.Writer) (err error) {
+func (ex *ExampleBatch) printResults(w http.ResponseWriter, req *http.Request) {
+
+	var temp strings.Builder
 
 	// Iterate over a batch of queued queries
-	for index, query := range ex.batch.QueuedQueries {
+	for _, query := range ex.batch.QueuedQueries {
 
 		// Read results from the current query
-		rows, err := ex.br.Query()
-		if err != nil {
-			return fmt.Errorf("iterateResults: %s", err)
+		rows, _ := ex.br.Query()
+
+		// Print SQL field of the current query
+		temp.WriteString(fmt.Sprintf("%v \n", query.SQL))
+
+		// Iterate over the selected records
+		//
+		for rows.Next() {
+			err := rows.Err()
+			if err != nil {
+				return
+			}
+
+			values, err := rows.Values()
+			if err != nil {
+				return
+			}
+
+			// Convert values to a string
+			temp.WriteString(fmt.Sprintf("%v \n", values))
 		}
+	}
 
-		if index > 0 {
-			// Print SQL field of the current query
-			fmt.Fprintf(file, "%v \n", query.SQL)
-
-			// Iterate over the selected records
-			//
-			var id, amount, descr = int64(0), int64(0), string("")
-			_, err = pgx.ForEachRow(rows, []any{&id, &descr, &amount}, func() error {
-				descr = "\"" + descr + "\""
-				fmt.Fprintf(file, "- %24v, amount: %d \n", descr, amount)
-				return err
-			})
-		}
+	if ex.output.Len() == 0 {
+		ex.output = temp
 	}
+	fmt.Fprint(w, ex.output.String())
 
-	return err
 }
 
 func (ex *ExampleBatch) requestBatch() (err error) {
@@ -79,10 +110,6 @@ func (ex *ExampleBatch) requestBatch() (err error) {
 
 func (ex *ExampleBatch) Close() (err error) {
 
-	// Delete all rows in table ledger
-	sql := `DELETE FROM ledger ;`
-	_, err = ex.db.Exec(context.Background(), sql)
-
 	// Close batch results object
 	ex.br.Close()
 
@@ -99,34 +126,37 @@ func main() {
 	if err != nil {
 		panic(err)
 	}
-	defer db.Close()
 
-	// Setup the example
-	var example = ExampleBatch{db: db, batch: &pgx.Batch{}}
+	// Setup the database
+	var example = ExampleBatch{
+		db:    db,
+		batch: &pgx.Batch{},
+	}
 	if err = example.databaseSetup(); err != nil {
 		panic(err)
 	}
-
-	// Add SQL queries to the queue
-	example.batch.Queue(
-		`INSERT INTO ledger(description, amount) VALUES ($1, $2), ($3, $4)`,
-		"first item", 1, "second item", 2)
-
-	example.batch.Queue("SELECT * FROM ledger")
-	example.batch.Queue("SELECT * FROM ledger WHERE amount = 1")
-
-	// Send a batch request and store results
+	defer example.Close()
+
+	// Add an example to database table
+	example.insertRow(
+		"The Adventures of Captain Pickle",
+		"Timothy T. Turtle",
+		"Adventure, Fantasy",
+		"Join Captain Pickle...",
+	)
+
+	// Add SQL queries to the queue for a batch operation
+	example.batch.Queue("SELECT title FROM metadata")
+	example.batch.Queue("SELECT authors FROM metadata")
+	example.batch.Queue("SELECT subject, description FROM metadata")
+
+	// Send the batch request to database
 	if err = example.requestBatch(); err != nil {
 		panic(err)
 	}
 
 	// Print batch result to ...
-	if err = example.printResults(os.Stdout); err != nil {
-		panic(err)
-	}
+	http.HandleFunc("/", example.printResults)
+	_ = http.ListenAndServe(":8080", nil)
 
-	// Close the example
-	if err = example.Close(); err != nil {
-		panic(err)
-	}
 }