时间：2021-07-01 10:21:17 帮助过：5人阅读
上述代码存在的问题非常明显，由于websql操作都是异步操作，当我们为了获取到websql操作的结果之后再进行后续操作时，往往是通过回调函数来实现的，当回调一多的时候，回调地狱就出现了，为了解决回调地狱问题，我将通过Promise来改写，后续调用时，可以直接通过await和async来调用，或者直接通过Promise链式调用也是可以的。
现在我将通过ES6的语法重写之前的封装类，为了应用ES6中js面向对象的思想，我这里用到了class，最终代码如下：
import { browserVersions } from ‘@/utils/utils.js‘;
class SmpWebSql {
constructor(options) {
options = options || {};
this.database = null;
this.DateBaseName = options.DateBaseName || ‘RedDB‘;
this.Version = options.Version || ‘1.0‘;
this.Description = options.Description || ‘智维离线工单数据库‘;
this.DataBaseSize = options.DataBaseSize || 2 * 1024 * 1024;
this.init();
}
/**
* 初始化数据库
*/
init() {
this.database = openDatabase(
this.DateBaseName,
this.Version,
this.Description,
this.DataBaseSize
);
}
/**
* 批量添加字段
* @param {*} tableName 表名
* @param {*} arr 更新的数据 [{key1：value1 , key2 : value2 ...},{key1：value1 , key2 : value2 ...}]
* @param {*} index BLOG字段所在的索引位置
* @param {*} isFirst 是否是第一次创建表
*/
addBlob(tableName, arr, index, isFirst = true) {
var _db = this.database;
var _me = this;
// eslint-disable-next-line promise/param-names
return new Promise(function(resovle, reject) {
if (arr == null) {
return this;
}
var keyC = [];
var keyI = [];
var _key = ‘‘;
arr = arr || [];
if (arr && arr.constructor == Array) {
for (var i in arr[0]) {
keyC.push(i);
keyI.push(i);
}
keyC[0] = keyC[0] + ‘ unique‘;
_key = keyI.join(‘,‘);
index = index == undefined ? 0 : index;
keyC[index] = keyC[index] + ‘ BLOB‘;
// eslint-disable-next-line promise/param-names
_db.transaction(function(tx, result) {
// var csql = ‘CREATE TABLE IF NOT EXISTS ‘ + tableName + ‘ (‘ + keyC.join(",") + ‘)‘;
// console.log(‘csql:‘ + csql);
if (isFirst == true) {
tx.executeSql(
‘CREATE TABLE IF NOT EXISTS ‘ +
tableName +
‘ (‘ +
keyC.join(‘,‘) +
‘)‘
);
}
// var sql = "";
for (var s = 0, _len = arr.length; s < _len; s++) {
var _value = _me.split(arr[s]);
// sql += ‘INSERT INTO ‘ + tableName + ‘ (‘ + _key + ‘) VALUES (‘ + _value + ‘)‘;
// console.log("sql:" + sql);
tx.executeSql(
‘INSERT INTO ‘ +
tableName +
‘ (‘ +
_key +
‘) VALUES (‘ +
_value +
‘)‘,
[],
function(tx, result) {
resovle(result.rowsAffected);
console.log(‘添加成功‘ + result.rowsAffected);
},
function(tx) {
console.error(‘添加失败‘);
// eslint-disable-next-line prefer-promise-reject-errors
reject(false);
}
);
}
_key = keyI = keyC = null;
resovle(arr.length);
});
}
}).catch(error => {
console.log(‘error :‘, error);
});
}
/**
* 批量添加字段
* @param {*} tableName 表名
* @param {*} arr 更新的数据 [{key1：value1 , key2 : value2 ...},{key1：value1 , key2 : value2 ...}]
* @param {*} index BLOG字段所在的索引位置
* @param {*} firstKey firstKey 第一个字段是否是主键（默认是）
* @param {*} isFirst 是否是第一次创建表
*/
patchAddBlob(tableName, arr, index, firstKey = true, isFirst = true) {
var _db = this.database;
var _me = this;
// eslint-disable-next-line promise/param-names
return new Promise(function(resovle, reject) {
if (arr == null) {
return this;
}
var keyC = [];
var keyI = [];
var _key = ‘‘;
arr = arr || [];
if (arr && arr.constructor == Array) {
for (var i in arr[0]) {
keyC.push(i);
keyI.push(i);
}
if (firstKey) {
keyC[0] = keyC[0] + ‘ unique‘;
}
_key = keyI.join(‘,‘);
index = index == undefined ? 0 : index;
keyC[index] = keyC[index] + ‘ text‘;
// eslint-disable-next-line promise/param-names
_db.transaction(function(tx, result) {
// var csql = ‘CREATE TABLE IF NOT EXISTS ‘ + tableName + ‘ (‘ + keyC.join(",") + ‘)‘;
// console.log(‘csql:‘ + csql);
if (isFirst == true) {
tx.executeSql(
‘CREATE TABLE IF NOT EXISTS ‘ +
tableName +
‘ (‘ +
keyC.join(‘,‘) +
‘)‘
);
}
var sql = ‘‘;
var _values = [];
for (var s = 0, _len = arr.length; s < _len; s++) {
_values.push(‘(‘ + _me.split(arr[s]) + ‘)‘);
}
sql =
‘INSERT INTO ‘ +
tableName +
‘ (‘ +
_key +
‘) VALUES ‘ +
_values.join(‘,‘);
// console.log(‘sql:‘ + sql);
tx.executeSql(
sql,
[],
function(tx, result) {
resovle(result.rowsAffected);
// console.log(‘添加成功‘+result.rowsAffected);
},
function(tx, error) {
console.error(‘添加失败‘, tx, error);
// eslint-disable-next-line prefer-promise-reject-errors
reject(false);
}
);
_key = keyI = keyC = null;
resovle(arr.length);
});
}
}).catch(error => {
console.log(‘error :‘, error);
});
}
/**
* 批量添加字段 注 ： 数据里面的第一个key 为主键
* @param {*} tableName 表名
* @param {*} arr arr 更新的数据 [{key1：value1 , key2 : value2 ...},{key1：value1 , key2 : value2 ...}]
* @param {*} firstKey firstKey 第一个字段是否是主键（默认是）
*/
add(tableName, arr, firstKey = true) {
var _me = this;
var _db = this.database;
// eslint-disable-next-line promise/param-names
return new Promise(function(resovle, reject) {
if (arr == null) {
return this;
}
var keyC = [];
var keyI = [];
var _key = ‘‘;
arr = arr || [];
if (arr && arr.constructor == Array) {
for (var i in arr[0]) {
keyC.push(i);
keyI.push(i);
}
if (firstKey) {
keyC[0] = keyC[0] + ‘ unique‘;
}
_key = keyI.join(‘,‘);
_db.transaction(function(tx) {
// /var csql = ‘CREATE TABLE IF NOT EXISTS ‘ + tableName + ‘ (‘ + keyC.join(",") + ‘)‘;
// console.log(‘csql:‘ + csql);
tx.executeSql(
‘CREATE TABLE IF NOT EXISTS ‘ +
tableName +
‘ (‘ +
keyC.join(‘,‘) +
‘)‘
);
// var sql = "";
for (var s = 0, _len = arr.length; s < _len; s++) {
var _value = _me.split(arr[s]);
// sql += ‘INSERT INTO ‘ + tableName + ‘ (‘ + _key + ‘) VALUES (‘ + _value + ‘)‘;
// console.log("sql:" + sql);
tx.executeSql(
‘INSERT INTO ‘ +
tableName +
‘ (‘ +
_key +
‘) VALUES (‘ +
_value +
‘)‘,
[],
function(tx, result) {
resovle(result.rowsAffected);
// console.log(‘添加成功‘+result.rowsAffected);
},
function(tx, error) {
console.error(‘添加失败‘, error);
// eslint-disable-next-line prefer-promise-reject-errors
reject(false);
}
);
}
_key = keyI = keyC = null;
resovle(arr.length);
});
}
}).catch(error => {
console.log(‘error :‘, error);
});
}
/**
* 批量添加行记录 注 ： 数据里面的第一个key 为主键
* @param {*} tableName 表名
* @param {*} arr arr 更新的数据 [{key1：value1 , key2 : value2 ...},{key1：value1 , key2 : value2 ...}]
* @param {*} firstKey firstKey 第一个字段是否是主键（默认是）
*/
patchAdd(tableName, arr, firstKey = true) {
var _me = this;
var _db = this.database;
// eslint-disable-next-line promise/param-names
return new Promise(function(resovle, reject) {
if (arr == null) {
return this;
}
var keyC = [];
var keyI = [];
var _key = ‘‘;
arr = arr || [];
if (arr && arr.constructor == Array) {
for (var i in arr[0]) {
keyC.push(i);
keyI.push(i);
}
if (firstKey) {
keyC[0] = keyC[0] + ‘ unique‘;
}
_key = keyI.join(‘,‘);
_db.transaction(function(tx) {
// /var csql = ‘CREATE TABLE IF NOT EXISTS ‘ + tableName + ‘ (‘ + keyC.join(",") + ‘)‘;
// console.log(‘csql:‘ + csql);
tx.executeSql(
‘CREATE TABLE IF NOT EXISTS ‘ +
tableName +
‘ (‘ +
keyC.join(‘,‘) +
‘)‘
);
var sql = ‘‘;
var _values = [];
for (var s = 0, _len = arr.length; s < _len; s++) {
_values.push(‘(‘ + _me.split(arr[s]) + ‘)‘);
}
sql =
‘INSERT INTO ‘ +
tableName +
‘ (‘ +
_key +
‘) VALUES ‘ +
_values.join(‘,‘);
console.log(‘sql:‘ + sql);
tx.executeSql(
sql,
[],
function(tx, result) {
resovle(result.rowsAffected);
// console.log(‘添加成功‘+result.rowsAffected);
},
function(tx, error) {
console.error(‘添加失败‘);
// eslint-disable-next-line prefer-promise-reject-errors
reject(false);
}
);
_key = keyI = keyC = null;
resovle(arr.length);
});
}
}).catch(error => {
console.log(‘error :‘, error);
});
}
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websql操作类封装
标签：lin name catch es6 esc import patch for 表名