go-migrate/internal/app/db-wrapper/postgres.go

package dbwrapper

import (
	"context"
	"errors"
	"fmt"
	"strings"

	dbdialects "git.ksdemosapps.com/kylesoda/go-migrate/internal/app/db-wrapper/db_dialects"
	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgxpool"
)

func init() {
	Register(dbdialects.Postgres, func() DbWrapper {
		return &postgresDbWrapper{dialect: dbdialects.Postgres}
	})
}

type postgresRowResult struct {
	row pgx.Row
}

func (pr *postgresRowResult) Scan(dest ...any) error {
	return pr.row.Scan(dest...)
}

type postgresRowsResult struct {
	columns []string
	rows    pgx.Rows
}

func (pr *postgresRowsResult) Close() error {
	pr.rows.Close()
	return nil
}

func (pr *postgresRowsResult) Columns() ([]string, error) {
	if pr.columns != nil {
		return pr.columns, nil
	}

	rawColumns := pr.rows.FieldDescriptions()
	if rawColumns == nil {
		return nil, errors.New("error retrieving columns")
	}

	columns := make([]string, 0, len(rawColumns))
	for _, rc := range rawColumns {
		columns = append(columns, rc.Name)
	}

	return columns, nil
}

func (pr *postgresRowsResult) Err() error {
	return pr.rows.Err()
}

func (pr *postgresRowsResult) Next() bool {
	return pr.rows.Next()
}

func (pr *postgresRowsResult) Scan(dest ...any) error {
	return pr.rows.Scan(dest...)
}

func (pr *postgresRowsResult) Values() ([]any, error) {
	return pr.rows.Values()
}

type postgresDbWrapper struct {
	db      *pgxpool.Pool
	dialect string
}

func (pw *postgresDbWrapper) Connect(ctx context.Context, dbUrl string) error {
	pool, err := pgxpool.New(ctx, dbUrl)
	if err != nil {
		return err
	}

	if err := pool.Ping(ctx); err != nil {
		pool.Close()
		return err
	}

	pw.db = pool
	return nil
}

func (pw *postgresDbWrapper) Close() error {
	pw.db.Close()
	return nil
}

func (pw *postgresDbWrapper) Exec(ctx context.Context, query string, args ...any) (ExecResult, error) {
	result, err := pw.db.Exec(ctx, query, args...)
	if err != nil {
		return ExecResult{}, err
	}

	return ExecResult{AffectedRows: result.RowsAffected()}, nil
}

func (pw *postgresDbWrapper) GetDialect() string {
	return pw.dialect
}

func (pw *postgresDbWrapper) Query(ctx context.Context, query string, args ...any) (RowsResult, error) {
	rows, err := pw.db.Query(ctx, query, args...)
	if err != nil {
		return nil, err
	}

	return &postgresRowsResult{columns: nil, rows: rows}, nil
}

func (pw *postgresDbWrapper) QueryRow(ctx context.Context, query string, args ...any) RowResult {
	row := pw.db.QueryRow(ctx, query, args...)
	return &postgresRowResult{row: row}
}

func (pw *postgresDbWrapper) SaveMassive(ctx context.Context, schema string, table string, columnNames []string, rows [][]any) (int64, error) {
	affectedRows, err := pw.db.CopyFrom(ctx, pgx.Identifier{schema, table}, columnNames, pgx.CopyFromRows(rows))
	if err != nil {
		return 0, err
	}

	return affectedRows, nil
}

func (pw *postgresDbWrapper) QueryFromObject(ctx context.Context, q ExtractionQuery) (RowsResult, error) {
	var sbQuery strings.Builder

	sbQuery.WriteString("SELECT ")

	if len(q.columns) == 0 {
		sbQuery.WriteString("*")
	} else {
		for i, col := range q.columns {
			switch col.Type() {
			case "GEOMETRY":
				fmt.Fprintf(&sbQuery, `ST_AsEWKB("%s") AS "%s"`, col.Name(), col.Name())
			default:
				fmt.Fprintf(&sbQuery, `"%s"`, col.Name())
			}

			if i < len(q.columns)-1 {
				sbQuery.WriteString(", ")
			}
		}
	}

	fmt.Fprintf(&sbQuery, ` FROM "%s"."%s"`, q.Schema, q.Table)

	if q.LowerLimit.IsValid || q.UpperLimit.IsValid {
		sbQuery.WriteString(" WHERE ")
		paramIdx := 1

		if q.LowerLimit.IsValid {
			fmt.Fprintf(&sbQuery, `"%s"`, q.PrimaryKey)
			if q.LowerLimit.IsInclusive {
				sbQuery.WriteString(" >=")
			} else {
				sbQuery.WriteString(" >")
			}
			fmt.Fprintf(&sbQuery, " $%d", paramIdx)
			paramIdx++
		}

		if q.LowerLimit.IsValid && q.UpperLimit.IsValid {
			sbQuery.WriteString(" AND ")
		}

		if q.UpperLimit.IsValid {
			fmt.Fprintf(&sbQuery, `"%s"`, q.PrimaryKey)
			if q.UpperLimit.IsInclusive {
				sbQuery.WriteString(" <=")
			} else {
				sbQuery.WriteString(" <")
			}
			fmt.Fprintf(&sbQuery, " $%d", paramIdx)
			paramIdx++
		}
	}

	fmt.Fprintf(&sbQuery, ` ORDER BY "%s" ASC`, q.PrimaryKey)

	queryString := sbQuery.String()

	var queryArgs []any

	if q.LowerLimit.IsValid {
		queryArgs = append(queryArgs, q.LowerLimit.Value)
	}

	if q.UpperLimit.IsValid {
		queryArgs = append(queryArgs, q.UpperLimit.Value)
	}

	return pw.Query(ctx, queryString, queryArgs...)
}