github.com/neugram/ng@v0.0.0-20180309130942-d472ff93d872/frame/sqlframe/sqlite.go (about)

     1  // Copyright 2015 The Neugram Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package sqlframe
     6  
     7  import (
     8  	"database/sql"
     9  	"fmt"
    10  	"math/big"
    11  
    12  	"neugram.io/ng/frame"
    13  )
    14  
    15  func sqliteLoad(db *sql.DB, table string) (frame.Frame, error) {
    16  	// TODO validate table name
    17  	f := &sqlFrame{
    18  		db:    db,
    19  		table: table,
    20  		limit: -1,
    21  	}
    22  	rows, err := db.Query("pragma table_info('" + table + "');")
    23  	if err != nil {
    24  		return nil, fmt.Errorf("sqlframe.Load: %v", err)
    25  	}
    26  	pkComponents := make(map[int]string)
    27  	defer rows.Close()
    28  	for rows.Next() {
    29  		var num int
    30  		var name string
    31  		var ty string
    32  		var empty interface{}
    33  		var pk int
    34  		if err := rows.Scan(&num, &name, &ty, &empty, &empty, &pk); err != nil {
    35  			return nil, fmt.Errorf("sqlframe.Load: %v", err)
    36  		}
    37  		f.sliceCols = append(f.sliceCols, name)
    38  		if pk > 0 {
    39  			pkComponents[pk-1] = name
    40  		}
    41  	}
    42  	if len(pkComponents) == 0 {
    43  		// An SQLite table without a primary key has a hidden primary
    44  		// key column called rowid. Add it to the list of all columns
    45  		// (but explicitly not the slice columns) and use it.
    46  		f.primaryKey = []string{"rowid"}
    47  	} else {
    48  		f.primaryKey = make([]string, len(pkComponents))
    49  		for pos, name := range pkComponents {
    50  			f.primaryKey[pos] = name
    51  		}
    52  	}
    53  
    54  	return f, nil
    55  }
    56  
    57  func sqliteScanBegin(frameDst []interface{}) ([]interface{}, error) {
    58  	sqlDst := make([]interface{}, len(frameDst))
    59  	for i, d := range frameDst {
    60  		switch d.(type) {
    61  		case *int64, *float32, *float64, *string:
    62  			sqlDst[i] = d
    63  		case *big.Int:
    64  			sqlDst[i] = new(int64)
    65  		case *big.Float:
    66  			sqlDst[i] = new(float64)
    67  		default:
    68  			return nil, fmt.Errorf("sqlframe: unsupported Get parameter type %T", d)
    69  		}
    70  	}
    71  	return sqlDst, nil
    72  }
    73  
    74  func sqliteScanEnd(frameDst, sqlDst []interface{}) {
    75  	for i, d := range frameDst {
    76  		switch d := d.(type) {
    77  		case *int64, *float32, *float64, *string:
    78  			// do nothing
    79  		case *big.Int:
    80  			d.SetInt64(*sqlDst[i].(*int64))
    81  		case *big.Float:
    82  			d.SetFloat64(*sqlDst[i].(*float64))
    83  		default:
    84  			panic(fmt.Sprintf("sqlframe: unsupported Get parameter type %T", d))
    85  		}
    86  	}
    87  }