Question

我正在创建一个表，并使用sqflite示例在其中保存数据。我希望将保存的表导出为csv文件。请任何人帮助我做同样的事情。我还经历了csv.drt。我已经将sqflite dbhelper的代码编写为文件，以保存数据文件，该代码已在下面的代码中显示，并且将我的代码附加到了将表中的数据显示为卡视图的地方。

dbhelper.dart

import 'dart:async';
import 'package:model/Manageinventory_class.dart';
import 'package:path/path.dart';
import 'package:sqflite/sqflite.dart';


class DBProvider {
  static final DBProvider _instance = new DBProvider.internal();

  factory DBProvider() => _instance;

  DBProvider.internal();

  final String tableNote = 'noteTable';
  final String columnId = 'id';
  final String columnItem = 'item';
  final String columnQuantity = 'quantity';
  final String columnCategory = 'category';
  final String columnUnit = 'unit';
  final String columnLocation = 'location';

  static Database _db;

  Future<Database> get db async {
    if (_db == null) _db = await initDb();

    return _db;
  }

  initDb() async {
    String databasesPath = await getDatabasesPath();
    String path = join(databasesPath, 'notes.db');

    // await deleteDatabase(path); // just for testing

    var db = await openDatabase(path, version: 1, onCreate: _onCreate);
    return db;
  }

  void _onCreate(Database db, int newVersion) async {
    await db.execute(
        'CREATE TABLE $tableNote($columnId INTEGER PRIMARY KEY, $columnItem REAL, $columnQuantity REAL, $columnCategory TEXT, $columnUnit TEXT, $columnLocation TEXT)');
  }

  Future<int> saveNote(Inventory note) async {
    var dbClient = await db;

    return await dbClient.insert(tableNote, note.toMap());
  }

  Future<List<Inventory>> getAllNotes() async {
    var dbClient = await db;
    var result = await dbClient
        .query(tableNote, columns: [columnId, columnItem, columnQuantity, columnCategory, columnUnit, columnLocation]);

    return result.map((r) => Inventory.fromMap(r)).toList();
  }

  Future<int> getCount() async {
    var dbClient = await db;
    return Sqflite.firstIntValue(await dbClient.rawQuery('SELECT COUNT(*) FROM $tableNote'));
  }

  Future<Inventory> getNote(int id) async {
    var dbClient = await db;
    List<Map> result = await dbClient.query(tableNote,
        columns: [columnId, columnItem, columnQuantity, columnCategory, columnUnit, columnLocation],
        where: '$columnId = ?',
        whereArgs: [id]);

    if (result.length > 0) {
      return new Inventory.fromMap(result.first);
    }

    return null;
  }

  Future<int> deleteNote(int id) async {
    var dbClient = await db;
    return await dbClient.delete(tableNote, where: '$columnId = ?', whereArgs: [id]);
  }

  Future<int> updateNote(Inventory note) async {
    var dbClient = await db;
    return await dbClient.update(tableNote, note.toMap(), where: "$columnId = ?", whereArgs: [note.id]);
  }

  Future close() async {
    return _db.close();
  }
}

Inventory.dart

import 'package:flutter/material.dart';
import 'package:database/dbhelper_manage_inventory.dart';
import 'package:model/Manageinventory_class.dart';

class ManageInventory extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return ManageInventoryState();
  }
}

class ManageInventoryState extends State<ManageInventory> {
  DBProvider _db = DBProvider();
  List<Inventory> _items = new List();
  int count = 0;

  @override
  void initState() {
    super.initState();

    _reloadItems();
  }

  void _reloadItems() async {
    _items.clear();
    var items = await _db.getAllNotes();

    setState(() {
      _items = items;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text('Inventories'),
        ),
        body: getManageStoreView());
  }

  getManageStoreView() {
    return _items.isEmpty
        ? Padding(
            padding: EdgeInsets.all(10.0),
            child: Center(
                child: Text(
              'No Stores created yet',
              style: TextStyle(fontSize: 20.0, fontWeight: FontWeight.normal),
            )))
        : ListView.builder(
            itemCount: _items.length,
            itemBuilder: (BuildContext context, int position) {
              return Card(
                  elevation: 2.0,
                  child: Column(
                    children: <Widget>[
                      ListTile(
                        title: Text('Item name :   ${_items[position].item}',
                            style: TextStyle(fontWeight: FontWeight.bold)),
                      ),
                      ListTile(
                        title: Text('Qauntity  :   ${_items[position].quantity}',
                            style: TextStyle(fontWeight: FontWeight.bold)),
                      ),
                      ListTile(
                        title: Text('Category :  ${_items[position].category}',
                            style: TextStyle(fontWeight: FontWeight.bold)),
                      ),
                      ListTile(
                        title: Text('Units : ${_items[position].unit}',
                            style: TextStyle(fontWeight: FontWeight.bold)),
                      ),
                      ListTile(
                        title: Text('Locations: ${_items[position].location}',
                            style: TextStyle(fontWeight: FontWeight.bold)),
                      ),
                    ],
                  ));
            },
          );
  }
}

Answer 1

来自https://github.com/tekartik/sqflite/issues/78#issuecomment-465916400
您可以使用mapListToCsv函数将List<Inventory>转换为csv
代码片段以将表导出到csv

var result = await db.query('MyTable');
var csv = mapListToCsv(result);

mapListToCsv函数https://github.com/tekartik/sqflite_more/blob/de853083cdbb977f8417970c4ea012de47a9cbcc/sqflite_porter/lib/utils/csv_utils.dart

import 'package:csv/csv.dart';

/// Convert a map list to csv
String mapListToCsv(List<Map<String, dynamic>> mapList,
    {ListToCsvConverter converter}) {
  if (mapList == null) {
    return null;
  }
  converter ??= const ListToCsvConverter();
  var data = <List>[];
  var keys = <String>[];
  var keyIndexMap = <String, int>{};

  // Add the key and fix previous records
  int _addKey(String key) {
    var index = keys.length;
    keyIndexMap[key] = index;
    keys.add(key);
    for (var dataRow in data) {
      dataRow.add(null);
    }
    return index;
  }

  for (var map in mapList) {
    // This list might grow if a new key is found
    var dataRow = List(keyIndexMap.length);
    // Fix missing key
    map.forEach((key, value) {
      var keyIndex = keyIndexMap[key];
      if (keyIndex == null) {
        // New key is found
        // Add it and fix previous data
        keyIndex = _addKey(key);
        // grow our list
        dataRow = List.from(dataRow, growable: true)..add(value);
      } else {
        dataRow[keyIndex] = value;
      }
    });
    data.add(dataRow);
  }
  return converter.convert(<List>[]
    ..add(keys)
    ..addAll(data));
}

如何在Flutter中将我的dbhelper表导出到csv文件

1 个答案: