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db_ctx.go
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db_ctx.go
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package goen
import (
"container/list"
"context"
"database/sql"
"fmt"
"log"
"reflect"
sqr "github.com/Masterminds/squirrel"
"github.com/kamichidu/goen/dialect"
"github.com/kamichidu/goen/internal"
)
// DBContext holds *sql.DB (and *sql.Tx) with contextual values.
// goen is intended to work with *sql.DB (and *sql.Tx) via DBContext.
type DBContext struct {
// This field is readonly.
// Sets via NewDBContext().
DB *sql.DB
// This field is readonly.
// Sets via UseTx(); or nil.
Tx *sql.Tx
// The patch compiler.
// This is used when need to compile patch to query.
Compiler PatchCompiler
// The logger for debugging.
// This is used when DebugMode(true).
Logger Logger
// The depth limit to avoid circular Include work.
// When this value is positive, Include works N-times.
// When this value is negative, Include works unlimited.
// When this value is 0, Include never works.
// Default is 10.
MaxIncludeDepth int
// The runner for each query.
// This field is indented to hold one of *sql.DB, *sql.Tx or *StmtCacher.
QueryRunner QueryRunner
dialect dialect.Dialect
debug bool
patchBuffer *PatchList
}
// NewDBContext creates DBContext with given dialectName and db.
func NewDBContext(dialectName string, db *sql.DB) *DBContext {
dialectsMu.RLock()
dialect, ok := dialects[dialectName]
dialectsMu.RUnlock()
if !ok {
panic(fmt.Sprintf("goen: unknown dialect %q (forgotten import?)", dialectName))
}
return &DBContext{
DB: db,
MaxIncludeDepth: 10,
QueryRunner: db,
dialect: dialect,
patchBuffer: NewPatchList(),
}
}
// Dialect returns dialect.Dialect holds by this context.
func (dbc *DBContext) Dialect() dialect.Dialect {
return dbc.dialect
}
// DebugMode sets debug flag.
func (dbc *DBContext) DebugMode(enabled bool) {
dbc.debug = enabled
}
// UseTx returns clone of current DBContext with given *sql.Tx.
func (dbc *DBContext) UseTx(tx *sql.Tx) *DBContext {
// replace db runner and copy state
var clone DBContext
clone = *dbc
clone.Tx = tx
if prep, ok := clone.QueryRunner.(*StmtCacher); ok {
txPrep := &txPreparer{tx: tx, PreparerContext: prep}
clone.QueryRunner = NewStmtCacher(txPrep)
} else {
clone.QueryRunner = tx
}
clone.patchBuffer = NewPatchList()
clone.patchBuffer.PushBackList(dbc.patchBuffer)
return &clone
}
// Patch adds raw patch into the buffer; without executing a query.
func (dbc *DBContext) Patch(v *Patch) {
dbc.patchBuffer.PushBack(v)
}
func (dbc *DBContext) QuerySqlizer(sqlizer sqr.Sqlizer) (*sql.Rows, error) {
return dbc.QuerySqlizerContext(context.Background(), sqlizer)
}
func (dbc *DBContext) QuerySqlizerContext(ctx context.Context, sqlizer sqr.Sqlizer) (*sql.Rows, error) {
query, args, err := sqlizer.ToSql()
if err != nil {
return nil, err
}
return dbc.QueryContext(ctx, query, args...)
}
func (dbc *DBContext) Query(query string, args ...interface{}) (*sql.Rows, error) {
return dbc.QueryContext(context.Background(), query, args...)
}
func (dbc *DBContext) QueryContext(ctx context.Context, query string, args ...interface{}) (*sql.Rows, error) {
if dbc.debug {
dbc.debugPrintf("goen: %q with %v", query, args)
}
return dbc.QueryRunner.QueryContext(ctx, query, args...)
}
func (dbc *DBContext) QueryRowSqlizer(sqlizer sqr.Sqlizer) *sql.Row {
return dbc.QueryRowSqlizerContext(context.Background(), sqlizer)
}
func (dbc *DBContext) QueryRowSqlizerContext(ctx context.Context, sqlizer sqr.Sqlizer) *sql.Row {
query, args, err := sqlizer.ToSql()
if err != nil {
panic(fmt.Sprintf("goen: sqlizer.ToSql returns error: %v", err))
}
return dbc.QueryRowContext(ctx, query, args...)
}
func (dbc *DBContext) QueryRow(query string, args ...interface{}) *sql.Row {
return dbc.QueryRowContext(context.Background(), query, args...)
}
func (dbc *DBContext) QueryRowContext(ctx context.Context, query string, args ...interface{}) *sql.Row {
if dbc.debug {
dbc.debugPrintf("goen: %q with %v", query, args)
}
return dbc.QueryRunner.QueryRowContext(ctx, query, args...)
}
func (dbc *DBContext) Scan(rows *sql.Rows, v interface{}) error {
out := reflect.ValueOf(v)
if out.Kind() != reflect.Ptr || out.IsNil() {
return fmt.Errorf("goen: Scan only accepts pointer of slice, but got %q", out.Type())
}
out = out.Elem()
rowTyp := out.Type().Elem()
cols, err := rows.ColumnTypes()
if err != nil {
return err
}
for rows.Next() {
rowVal, err := dbc.scanRow(rows, cols, rowTyp)
if err != nil {
return err
}
out = reflect.Append(out, rowVal)
}
reflect.ValueOf(v).Elem().Set(out)
return nil
}
func (dbc *DBContext) Include(v interface{}, sc *ScopeCache, loader IncludeLoader) error {
return dbc.IncludeContext(context.Background(), v, sc, loader)
}
func (dbc *DBContext) IncludeContext(ctx context.Context, v interface{}, sc *ScopeCache, loader IncludeLoader) error {
recordsList := list.New()
recordsList.PushBack(v)
for depth := 0; depth < dbc.MaxIncludeDepth; depth++ {
nextRecordsList := list.New()
for records := recordsList.Front(); records != nil; records = records.Next() {
if err := loader.Load(ctx, (*IncludeBuffer)(nextRecordsList), sc, records.Value); err != nil {
return err
}
}
if nextRecordsList.Len() == 0 {
return nil
}
recordsList = nextRecordsList
}
return nil
}
func (dbc *DBContext) CompilePatch() *SqlizerList {
patches := *dbc.patchBuffer
dbc.patchBuffer.Init()
compiler := dbc.Compiler
if compiler == nil {
compiler = DefaultCompiler
}
opts := &CompilerOptions{
Dialect: dbc.Dialect(),
Patches: &patches,
}
return compiler.Compile(opts)
}
func (dbc *DBContext) SaveChanges() error {
return dbc.SaveChangesContext(context.Background())
}
func (dbc *DBContext) SaveChangesContext(ctx context.Context) error {
sqlizers := dbc.CompilePatch()
for curr := sqlizers.Front(); curr != nil; curr = curr.Next() {
sqlizer := curr.GetValue()
query, args, err := sqlizer.ToSql()
if err != nil {
return err
}
if dbc.debug {
dbc.debugPrintf("goen: %q with %v", query, args)
}
if _, err := dbc.QueryRunner.ExecContext(ctx, query, args...); err != nil {
return err
}
}
return nil
}
// scanRow scans a row as given rowTyp.
func (dbc *DBContext) scanRow(rows sqr.RowScanner, cols []*sql.ColumnType, rowTyp reflect.Type) (reflect.Value, error) {
switch rowTyp.Kind() {
case reflect.Slice:
return dbc.scanRowAsSlice(rows, cols, rowTyp)
case reflect.Map:
return dbc.scanRowAsMap(rows, cols, rowTyp)
case reflect.Ptr:
res, err := dbc.scanRow(rows, cols, rowTyp.Elem())
if res.CanAddr() {
res = res.Addr()
}
return res, err
case reflect.Struct:
return dbc.scanRowAsStruct(rows, cols, rowTyp)
default:
return reflect.Value{}, fmt.Errorf("goen: unsupported scan type %q", rowTyp)
}
}
// scanRowAsSlice scans a row as slice.
func (dbc *DBContext) scanRowAsSlice(rows sqr.RowScanner, cols []*sql.ColumnType, rowTyp reflect.Type) (reflect.Value, error) {
dest := make([]interface{}, len(cols))
args := make([]interface{}, len(cols))
for i := range cols {
// if possible to get ScanType, suggest to use its type
if typ := dbc.dialect.ScanTypeOf(cols[i]); typ != nil {
dest[i] = reflect.New(typ).Elem()
}
args[i] = &dest[i]
}
if err := rows.Scan(args...); err != nil {
return reflect.Value{}, err
}
return reflect.ValueOf(dest), nil
}
// scanRowAsMap scans a row as map.
func (dbc *DBContext) scanRowAsMap(rows sqr.RowScanner, cols []*sql.ColumnType, rowTyp reflect.Type) (reflect.Value, error) {
rvals, err := dbc.scanRowAsSlice(rows, cols, reflect.TypeOf([]interface{}{}))
if err != nil {
return reflect.Value{}, err
}
dest := map[string]interface{}{}
for i := range cols {
dest[cols[i].Name()] = rvals.Index(i).Interface()
}
return reflect.ValueOf(dest), nil
}
// scanRowAsStruct scans a row as struct.
func (dbc *DBContext) scanRowAsStruct(rows sqr.RowScanner, cols []*sql.ColumnType, rowTyp reflect.Type) (reflect.Value, error) {
dest := reflect.New(rowTyp).Elem()
strct := internal.NewStructFromReflect(rowTyp)
fields := internal.FieldsByFunc(strct.Fields(), internal.IsColumnField)
args := make([]interface{}, len(cols))
for i := range cols {
var rfv reflect.Value
if field, ok := internal.FieldByFunc(fields, internal.EqColumnName(cols[i].Name())); ok {
rfv = dest.FieldByName(field.Name())
}
if !rfv.IsValid() {
panic(fmt.Sprintf("goen: unknown struct field for column %q on %v", cols[i].Name(), rowTyp))
}
args[i] = rfv.Addr().Interface()
}
if err := rows.Scan(args...); err != nil {
return reflect.Value{}, err
}
return dest, nil
}
func (dbc *DBContext) debugPrint(v ...interface{}) {
if l, ok := dbc.Logger.(leveledLogger); ok {
l.Debug(v...)
} else if dbc.Logger != nil {
dbc.Logger.Print(v...)
} else {
log.Print(v...)
}
}
func (dbc *DBContext) debugPrintf(format string, args ...interface{}) {
if l, ok := dbc.Logger.(leveledLogger); ok {
l.Debugf(format, args...)
} else if dbc.Logger != nil {
dbc.Logger.Printf(format, args...)
} else {
log.Printf(format, args...)
}
}