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|
package query
import (
"context"
"database/sql"
"fmt"
"strconv"
"strings"
"time"
)
// Dump returns a SQL text dump of all rows across all tables, similar to
// sqlite3's dump feature.
func Dump(ctx context.Context, tx *sql.Tx, schemaOnly bool) (string, error) {
entitiesSchemas, entityNames, err := getEntitiesSchemas(ctx, tx)
if err != nil {
return "", err
}
// Begin dump string.
var builder strings.Builder
builder.WriteString("PRAGMA foreign_keys=OFF;\n")
builder.WriteString("BEGIN TRANSACTION;\n")
// For each table, write the schema and optionally write the data.
for _, tableName := range entityNames {
builder.WriteString(entitiesSchemas[tableName][1] + "\n")
if !schemaOnly && entitiesSchemas[tableName][0] == "table" {
tableData, err := getTableData(ctx, tx, tableName)
if err != nil {
return "", err
}
for _, stmt := range tableData {
builder.WriteString(stmt + "\n")
}
}
}
// Sequences (unless the schemaOnly flag is true).
if !schemaOnly {
builder.WriteString("DELETE FROM sqlite_sequence;\n")
tableData, err := getTableData(ctx, tx, "sqlite_sequence")
if err != nil {
return "", fmt.Errorf("Failed to dump table sqlite_sequence: %w", err)
}
for _, stmt := range tableData {
builder.WriteString(stmt + "\n")
}
}
// Commit.
builder.WriteString("COMMIT;\n")
return builder.String(), nil
}
// getEntitiesSchemas gets all the tables, their kind, and their schema, as well as a list of entity names in their default order from
// the sqlite_master table. The returned map values are arrays of length 2 whose first element contains the entity type and the second
// contains it's schema.
func getEntitiesSchemas(ctx context.Context, tx *sql.Tx) (map[string][2]string, []string, error) {
rows, err := tx.QueryContext(ctx, `SELECT name, type, sql FROM sqlite_master WHERE name NOT LIKE 'sqlite_%' ORDER BY rowid`)
if err != nil {
return nil, nil, fmt.Errorf("Could not get table names and their schema: %w", err)
}
defer func() { _ = rows.Close() }()
tablesSchemas := make(map[string][2]string)
var names []string
for rows.Next() {
var name string
var kind string
var schema string
err := rows.Scan(&name, &kind, &schema)
if err != nil {
return nil, nil, fmt.Errorf("Could not scan table name and schema: %w", err)
}
// This is based on logic from dump_callback in sqlite source for sqlite3_db_dump function.
if strings.HasPrefix(schema, `CREATE TABLE "`) {
schema = strings.Replace(schema, "CREATE TABLE", "CREATE TABLE IF NOT EXISTS", 1)
}
names = append(names, name)
tablesSchemas[name] = [2]string{kind, schema + ";"}
}
return tablesSchemas, names, nil
}
// getTableData gets all the data for a single table, returning a string slice where each element is an insert statement
// for the data.
func getTableData(ctx context.Context, tx *sql.Tx, table string) ([]string, error) {
var statements []string
// Query all rows.
rows, err := tx.QueryContext(ctx, fmt.Sprintf("SELECT * FROM %s ORDER BY rowid", table))
if err != nil {
return nil, fmt.Errorf("Failed to fetch rows for table %q: %w", table, err)
}
defer func() { _ = rows.Close() }()
// Get the column names.
columns, err := rows.Columns()
if err != nil {
return nil, fmt.Errorf("Failed to get columns for table %q: %w", table, err)
}
// Generate an INSERT statement for each row.
for i := 0; rows.Next(); i++ {
raw := make([]any, len(columns)) // Raw column values
row := make([]any, len(columns))
for i := range raw {
row[i] = &raw[i]
}
err := rows.Scan(row...)
if err != nil {
return nil, fmt.Errorf("Failed to scan row %d in table %q: %w", i, table, err)
}
values := make([]string, len(columns))
for j, v := range raw {
switch v := v.(type) {
case int64:
values[j] = strconv.FormatInt(v, 10)
case string:
// This is based on logic from dump_callback in sqlite source for sqlite3_db_dump function.
v = fmt.Sprintf("'%s'", strings.ReplaceAll(v, "'", "''"))
if strings.Contains(v, "\r") {
v = "replace(" + strings.ReplaceAll(v, "\r", "\\r") + ",'\\r',char(13))"
}
if strings.Contains(v, "\n") {
v = "replace(" + strings.ReplaceAll(v, "\n", "\\n") + ",'\\n',char(10))"
}
values[j] = v
case []byte:
values[j] = fmt.Sprintf("'%s'", string(v))
case time.Time:
// Try and match the sqlite3 .dump output format.
format := "2006-01-02 15:04:05"
if v.Nanosecond() > 0 {
format = format + ".000000000"
}
format = format + "-07:00"
values[j] = "'" + v.Format(format) + "'"
default:
if v != nil {
return nil, fmt.Errorf("Bad type in column %q of row %d in table %q", columns[j], i, table)
}
values[j] = "NULL"
}
}
statement := fmt.Sprintf("INSERT INTO %s VALUES(%s);", table, strings.Join(values, ","))
statements = append(statements, statement)
}
return statements, nil
}
|
