在启动SELECT请求之前,我有多个INSERT需要完成。我的问题是,当SELECT触发时,INSERT还没有完成。
建立数据库处理工厂:
databaseFactory.js
factory.insertIntoTable= function (database, data) {
var sqlCommand = 'INSERT INTO blablabla';
database.transaction(function(tx) {
database.executeSql(sqlCommand, [data.thingsToInsert], function (resultSet) {
console.log('success: insertIntoTable');
}, function (error) {
console.log('SELECT error: ' + error.message);
});
}, function(error) {
console.log('transaction error: ' + error.message);
database.close();
}, function() {
console.log('transaction ok: insertIntoTable');
});
};
app.js
ionic.Platform.ready(function () {
if (window.cordova && window.cordova.plugins.Keyboard) {
cordova.plugins.Keyboard.hideKeyboardAccessoryBar(true);
cordova.plugins.Keyboard.disableScroll(true);
};
if(window.StatusBar) {
StatusBar.styleDefault();
}
db = window.sqlitePlugin.openDatabase({name: 'myDbName.db', location: 'default'});
if (window.Connection) {
if (navigator.connection.type !== Connection.NONE) {
databaseFactory.createTables(db);
MyService.getStuffFromAPI().then(function(result) {
for (var index = 0; index < result[0].campaigns.length; index++) {
databaseFactory.insertIntoTable(db, result[0].campaigns[index]);
}
var selectResult = databaseFactory.selectFromCampaigns();
console.log(selectResult); //This log comes earlier than the above inserts could finish.
}, function(result) {
console.log(result);
});
}
}
});
不管怎样,INSERT运行良好,我确实检查过了。
我知道datebase.transaction是异步的,所以也尝试过使用单个db.executeSQL命令,但即使在向工厂添加$q resolve,reject时也遇到了同样的问题。我真的需要一些帮助,谢谢!
每次插入都返回一个promise。在一系列承诺中遵守这些承诺,并使用$q.all等待所有承诺完成。
示例:用于插入对象的工厂方法
function insert(object){
var deferred = $q.defer(); //IMPORTANT
var query = "INSERT INTO objectTable (attr1, attr2) VALUES (?,?)";
$cordovaSQLite.execute(db, query, [object.attr1, object.attr2]).then(function(res) { //db object is the result of the openDB method
console.log("INSERT ID -> " + res.insertId);
deferred.resolve(res); //"return" res in the success method
}, function (err) {
console.error(JSON.stringify(err));
deferred.reject(err); //"return" the error in the error method
});
return deferred.promise; //the function returns the promise to wait for
}
然后,在每个插入中:
promises.push(yourService.insert(obj).then(function(result){ //"result" --> deferred.resolve(res);
//success code
}, function(error){ //"error" --> deferred.reject(err);
//error code
}));
最后:
$q.all(promises).then(function(){//do your selects}, function(err){//error!});
希望能有所帮助。
有关$q和$q.all的更多信息:https://docs.angularjs.org/api/ng/service/$q#所有
还有另一个例子:https://www.jonathanfielding.com/combining-promises-angular/
问题是我使用database.transaction(function (tx){})
的方式,因为它本身是一个异步函数,在函数体内部,我可以进行同步CRUD操作,它们将按顺序进行
app.js(已修复)
ionic.Platform.ready(function () {
if (window.cordova && window.cordova.plugins.Keyboard) {
cordova.plugins.Keyboard.hideKeyboardAccessoryBar(true);
cordova.plugins.Keyboard.disableScroll(true);
};
if(window.StatusBar) {
StatusBar.styleDefault();
}
db = window.sqlitePlugin.openDatabase({name: 'MagicalWonder.db', location: 'default'});
if (window.Connection) {
if (navigator.connection.type !== Connection.NONE) {
MyService.getMyPreciousData().then(function(result) {
db.transaction(function(tx) {
databaseFactory.createTable(tx);
for (var index = 0; index < result[0].campaigns.length; index++) {
databaseFactory.insertIntoTable(tx, result[0].myPreciousData[index]);
}
// HERE I CAN MAKE THE SELECT REQUESTS
}, function(error) {
console.log('transaction error: ' + error.message);
database.close();
}, function() {
console.log('transactions successfully done.');
});
}, function(result) {
console.log(result);
});
}
}
});
工厂法(固定)
factory.insertIntoTable = function (tx, data) {
var sqlCommand = 'INSERT INTO wanders (' +
'id, ' +
'magic_spell) values (?,?)';
tx.executeSql(sqlCommand, [data.id, data.magic_spell], function (tx, resultSet) {
console.log('Success: insertIntoBookOfWonder');
}, function (tx, error) {
console.log('SELECT error: ' + error.message);
});
};