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db.go
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db.go
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/*
package chai implements an embedded SQL database.
*/
package chai
import (
"bufio"
"bytes"
"context"
"database/sql"
"database/sql/driver"
"io"
"github.com/chaisql/chai/internal/database"
"github.com/chaisql/chai/internal/database/catalogstore"
"github.com/chaisql/chai/internal/environment"
errs "github.com/chaisql/chai/internal/errors"
"github.com/chaisql/chai/internal/query"
"github.com/chaisql/chai/internal/query/statement"
"github.com/chaisql/chai/internal/row"
"github.com/chaisql/chai/internal/sql/parser"
"github.com/chaisql/chai/internal/stream"
"github.com/chaisql/chai/internal/types"
"github.com/cockroachdb/errors"
)
// DB represents a collection of tables.
type DB struct {
DB *database.Database
ctx context.Context
}
// Open creates a Chai database at the given path.
// If path is equal to ":memory:" it will open an in-memory database,
// otherwise it will create an on-disk database.
func Open(path string) (*DB, error) {
db, err := database.Open(path, &database.Options{
CatalogLoader: catalogstore.LoadCatalog,
})
if err != nil {
return nil, err
}
return &DB{
DB: db,
}, nil
}
func (db *DB) Connect() (*Connection, error) {
conn, err := db.DB.Connect()
if err != nil {
return nil, err
}
return &Connection{
db: db,
Conn: conn,
}, nil
}
// WithContext creates a new database handle using the given context for every operation.
func (db DB) WithContext(ctx context.Context) *DB {
db.ctx = ctx
return &db
}
func (db *DB) withConn(fn func(*Connection) error) error {
conn, err := db.Connect()
if err != nil {
return err
}
defer conn.Close()
return fn(conn)
}
// QueryRow runs the query and returns the first row.
func (db *DB) QueryRow(q string, args ...any) (r *Row, err error) {
err = db.withConn(func(c *Connection) error {
r, err = c.QueryRow(q, args...)
return err
})
return
}
// Exec a query against the database without returning the result.
func (db *DB) Exec(q string, args ...any) error {
return db.withConn(func(c *Connection) error {
return c.Exec(q, args...)
})
}
// Close the database.
func (db *DB) Close() error {
return db.DB.Close()
}
type Connection struct {
db *DB
Conn *database.Connection
}
// Begin starts a new transaction.
// The returned transaction must be closed either by calling Rollback or Commit.
func (c *Connection) Begin(writable bool) (*Tx, error) {
_, err := c.Conn.BeginTx(&database.TxOptions{
ReadOnly: !writable,
})
if err != nil {
return nil, err
}
return &Tx{
conn: c,
}, nil
}
// View starts a read only transaction, runs fn and automatically rolls it back.
func (c *Connection) View(fn func(tx *Tx) error) error {
tx, err := c.Begin(false)
if err != nil {
return err
}
defer tx.Rollback()
return fn(tx)
}
// Update starts a read-write transaction, runs fn and automatically commits it.
func (c *Connection) Update(fn func(tx *Tx) error) error {
tx, err := c.Begin(true)
if err != nil {
return err
}
defer tx.Rollback()
err = fn(tx)
if err != nil {
return err
}
return tx.Commit()
}
// Query the database and return the result.
// The returned result must always be closed after usage.
func (c *Connection) Query(q string, args ...any) (*Result, error) {
stmt, err := c.Prepare(q)
if err != nil {
return nil, err
}
res, err := stmt.Query(args...)
if err != nil {
return nil, err
}
res.conn = c
return res, nil
}
// QueryRow runs the query and returns the first row.
func (c *Connection) QueryRow(q string, args ...any) (*Row, error) {
stmt, err := c.Prepare(q)
if err != nil {
return nil, err
}
return stmt.QueryRow(args...)
}
// Exec a query against the database without returning the result.
func (c *Connection) Exec(q string, args ...any) error {
stmt, err := c.Prepare(q)
if err != nil {
return err
}
return stmt.Exec(args...)
}
// Prepare parses the query and returns a prepared statement.
func (c *Connection) Prepare(q string) (*Statement, error) {
pq, err := parser.ParseQuery(q)
if err != nil {
return nil, err
}
err = pq.Prepare(newQueryContext(c, nil))
if err != nil {
return nil, err
}
return &Statement{
pq: pq,
conn: c,
}, nil
}
func (c *Connection) Close() error {
return c.Conn.Close()
}
// Tx represents a database transaction. It provides methods for managing the
// collection of tables and the transaction itself.
// Tx is either read-only or read/write. Read-only can be used to read tables
// and read/write can be used to read, create, delete and modify tables.
type Tx struct {
conn *Connection
}
// Rollback the transaction. Can be used safely after commit.
func (tx *Tx) Rollback() error {
t := tx.conn.Conn.GetTx()
if t == nil {
return errors.New("transaction has already been committed or rolled back")
}
return t.Rollback()
}
// Commit the transaction. Calling this method on read-only transactions
// will return an error.
func (tx *Tx) Commit() error {
t := tx.conn.Conn.GetTx()
if t == nil {
return errors.New("transaction has already been committed or rolled back")
}
return t.Commit()
}
// Query the database withing the transaction and returns the result.
// Closing the returned result after usage is not mandatory.
func (tx *Tx) Query(q string, args ...any) (*Result, error) {
stmt, err := tx.Prepare(q)
if err != nil {
return nil, err
}
return stmt.Query(args...)
}
// QueryRow runs the query and returns the first row.
func (tx *Tx) QueryRow(q string, args ...any) (*Row, error) {
stmt, err := tx.Prepare(q)
if err != nil {
return nil, err
}
return stmt.QueryRow(args...)
}
// Exec a query against the database within tx and without returning the result.
func (tx *Tx) Exec(q string, args ...any) (err error) {
stmt, err := tx.Prepare(q)
if err != nil {
return err
}
return stmt.Exec(args...)
}
// Prepare parses the query and returns a prepared statement.
func (tx *Tx) Prepare(q string) (*Statement, error) {
pq, err := parser.ParseQuery(q)
if err != nil {
return nil, err
}
err = pq.Prepare(newQueryContext(tx.conn, nil))
if err != nil {
return nil, err
}
return &Statement{
pq: pq,
conn: tx.conn,
tx: tx,
}, nil
}
// Statement is a prepared statement. If Statement has been created on a Tx,
// it will only be valid until Tx closes. If it has been created on a DB, it
// is valid until the DB closes.
// It's safe for concurrent use by multiple goroutines.
type Statement struct {
pq query.Query
conn *Connection
tx *Tx
}
// Query the database and return the result.
// The returned result must always be closed after usage.
func (s *Statement) Query(args ...any) (*Result, error) {
var r *statement.Result
var err error
r, err = s.pq.Run(newQueryContext(s.conn, argsToParams(args)))
if err != nil {
return nil, err
}
return &Result{result: r, ctx: s.conn.db.ctx}, nil
}
func argsToParams(args []interface{}) []environment.Param {
nv := make([]environment.Param, len(args))
for i := range args {
switch t := args[i].(type) {
case sql.NamedArg:
nv[i].Name = t.Name
nv[i].Value = t.Value
case *sql.NamedArg:
nv[i].Name = t.Name
nv[i].Value = t.Value
case driver.NamedValue:
nv[i].Name = t.Name
nv[i].Value = t.Value
case *driver.NamedValue:
nv[i].Name = t.Name
nv[i].Value = t.Value
case *environment.Param:
nv[i] = *t
case environment.Param:
nv[i] = t
default:
nv[i].Value = args[i]
}
}
return nv
}
// QueryRow runs the query and returns the first row.
func (s *Statement) QueryRow(args ...any) (r *Row, err error) {
res, err := s.Query(args...)
if err != nil {
return nil, err
}
defer func() {
er := res.Close()
if err == nil {
err = er
}
}()
return res.GetFirst()
}
// Exec a query against the database without returning the result.
func (s *Statement) Exec(args ...any) (err error) {
res, err := s.Query(args...)
if err != nil {
return err
}
defer func() {
er := res.Close()
if err == nil {
err = er
}
}()
return res.Iterate(func(*Row) error {
return nil
})
}
// Result of a query.
type Result struct {
result *statement.Result
ctx context.Context
conn *Connection
}
func (r *Result) Iterate(fn func(r *Row) error) error {
var row Row
if r.ctx == nil {
return r.result.Iterate(func(dr database.Row) error {
row.Row = dr
return fn(&row)
})
}
return r.result.Iterate(func(dr database.Row) error {
if err := r.ctx.Err(); err != nil {
return err
}
row.Row = dr
return fn(&row)
})
}
func (r *Result) GetFirst() (*Row, error) {
var rr *Row
err := r.Iterate(func(row *Row) error {
rr = row.Clone()
return stream.ErrStreamClosed
})
if err != nil {
return nil, err
}
if rr == nil {
return nil, errors.WithStack(errs.NewRowNotFoundError())
}
return rr, nil
}
func (r *Result) Columns() ([]string, error) {
if r.result.Iterator == nil {
return nil, nil
}
stmt, ok := r.result.Iterator.(*statement.StreamStmtIterator)
if !ok || stmt.Stream.Op == nil {
return nil, nil
}
var env environment.Environment
env.DB = stmt.Context.DB
env.Tx = stmt.Context.Tx
env.SetParams(stmt.Context.Params)
return stmt.Stream.Columns(&env)
}
// Close the result stream.
func (r *Result) Close() (err error) {
if r == nil {
return nil
}
err = r.result.Close()
return err
}
func (r *Result) MarshalJSON() ([]byte, error) {
var buf bytes.Buffer
err := r.MarshalJSONTo(&buf)
if err != nil {
return nil, err
}
return buf.Bytes(), nil
}
func (r *Result) MarshalJSONTo(w io.Writer) error {
buf := bufio.NewWriter(w)
buf.WriteByte('[')
first := true
err := r.result.Iterate(func(r database.Row) error {
if !first {
buf.WriteString(", ")
} else {
first = false
}
data, err := r.MarshalJSON()
if err != nil {
return err
}
_, err = buf.Write(data)
return err
})
if err != nil {
return err
}
buf.WriteByte(']')
return buf.Flush()
}
func newQueryContext(conn *Connection, params []environment.Param) *query.Context {
return &query.Context{
Ctx: conn.db.ctx,
DB: conn.db.DB,
Conn: conn.Conn,
Params: params,
}
}
type Row struct {
Row database.Row
}
func (r *Row) Clone() *Row {
var rr Row
cb := row.NewColumnBuffer()
err := cb.Copy(r.Row)
if err != nil {
panic(err)
}
var br database.BasicRow
br.ResetWith(r.Row.TableName(), r.Row.Key(), cb)
rr.Row = &br
return &rr
}
func (r *Row) Columns() ([]string, error) {
var cols []string
err := r.Row.Iterate(func(column string, value types.Value) error {
cols = append(cols, column)
return nil
})
if err != nil {
return nil, err
}
return cols, nil
}
func (r *Row) GetColumnType(column string) (string, error) {
v, err := r.Row.Get(column)
if errors.Is(err, types.ErrColumnNotFound) {
return "", err
}
return v.Type().String(), err
}
func (r *Row) ScanColumn(column string, dest any) error {
return row.ScanColumn(r.Row, column, dest)
}
func (r *Row) Scan(dest ...any) error {
return row.Scan(r.Row, dest...)
}
func (r *Row) StructScan(dest any) error {
return row.StructScan(r.Row, dest)
}
func (r *Row) MapScan(dest map[string]any) error {
return row.MapScan(r.Row, dest)
}
func (r *Row) MarshalJSON() ([]byte, error) {
return r.Row.MarshalJSON()
}