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migration_sql.go
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migration_sql.go
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package goose
import (
"bufio"
"bytes"
"database/sql"
"io"
"log"
"os"
"path/filepath"
"strings"
)
const sqlCmdPrefix = "-- +goose "
// Checks the line to see if the line has a statement-ending semicolon
// or if the line contains a double-dash comment.
func endsWithSemicolon(line string) bool {
prev := ""
scanner := bufio.NewScanner(strings.NewReader(line))
scanner.Split(bufio.ScanWords)
for scanner.Scan() {
word := scanner.Text()
if strings.HasPrefix(word, "--") {
break
}
prev = word
}
return strings.HasSuffix(prev, ";")
}
// Split the given sql script into individual statements.
//
// The base case is to simply split on semicolons, as these
// naturally terminate a statement.
//
// However, more complex cases like pl/pgsql can have semicolons
// within a statement. For these cases, we provide the explicit annotations
// 'StatementBegin' and 'StatementEnd' to allow the script to
// tell us to ignore semicolons.
func splitSQLStatements(r io.Reader, direction bool) (stmts []string) {
var buf bytes.Buffer
scanner := bufio.NewScanner(r)
// track the count of each section
// so we can diagnose scripts with no annotations
upSections := 0
downSections := 0
statementEnded := false
ignoreSemicolons := false
directionIsActive := false
for scanner.Scan() {
line := scanner.Text()
// handle any goose-specific commands
if strings.HasPrefix(line, sqlCmdPrefix) {
cmd := strings.TrimSpace(line[len(sqlCmdPrefix):])
switch cmd {
case "Up":
directionIsActive = (direction == true)
upSections++
break
case "Down":
directionIsActive = (direction == false)
downSections++
break
case "StatementBegin":
if directionIsActive {
ignoreSemicolons = true
}
break
case "StatementEnd":
if directionIsActive {
statementEnded = (ignoreSemicolons == true)
ignoreSemicolons = false
}
break
}
}
if !directionIsActive {
continue
}
if _, err := buf.WriteString(line + "\n"); err != nil {
log.Fatalf("io err: %v", err)
}
// Wrap up the two supported cases: 1) basic with semicolon; 2) psql statement
// Lines that end with semicolon that are in a statement block
// do not conclude statement.
if (!ignoreSemicolons && endsWithSemicolon(line)) || statementEnded {
statementEnded = false
stmts = append(stmts, buf.String())
buf.Reset()
}
}
if err := scanner.Err(); err != nil {
log.Fatalf("scanning migration: %v", err)
}
// diagnose likely migration script errors
if ignoreSemicolons {
log.Println("WARNING: saw '-- +goose StatementBegin' with no matching '-- +goose StatementEnd'")
}
if bufferRemaining := strings.TrimSpace(buf.String()); len(bufferRemaining) > 0 {
log.Printf("WARNING: Unexpected unfinished SQL query: %s. Missing a semicolon?\n", bufferRemaining)
}
if upSections == 0 && downSections == 0 {
log.Fatalf(`ERROR: no Up/Down annotations found, so no statements were executed.
See https://bitbucket.org/liamstask/goose/overview for details.`)
}
return
}
// Run a migration specified in raw SQL.
//
// Sections of the script can be annotated with a special comment,
// starting with "-- +goose" to specify whether the section should
// be applied during an Up or Down migration
//
// All statements following an Up or Down directive are grouped together
// until another direction directive is found.
func (c *Client) runSQLMigration(db *sql.DB, scriptFile string, v int64, direction bool) error {
tx, err := db.Begin()
if err != nil {
log.Fatal("db.Begin:", err)
}
f, err := os.Open(scriptFile)
if err != nil {
log.Fatal(err)
}
// find each statement, checking annotations for up/down direction
// and execute each of them in the current transaction.
// Commits the transaction if successfully applied each statement and
// records the version into the version table or returns an error and
// rolls back the transaction.
for _, query := range splitSQLStatements(f, direction) {
if _, err = tx.Exec(query); err != nil {
tx.Rollback()
log.Fatalf("FAIL %s (%v), quitting migration.", filepath.Base(scriptFile), err)
return err
}
}
if err = c.FinalizeMigration(tx, direction, v); err != nil {
log.Fatalf("error finalizing migration %s, quitting. (%v)", filepath.Base(scriptFile), err)
}
return nil
}