在这里,我编写了代码以查找sqlite表的行,以及如果可用的行,则返回false,否则为true。
在这里代码
function findPageID(pickId)
{
this.db.transaction(function(tx){
tx.executeSql("SELECT pid FROM page WHERE pid="+pickId, [], function(tx, result) {
if(result) {
if(result.rows.length > 0){
return false;
}
else
{
return true;
}
}
})
})
}
当我尝试使用console.log(findPageID(pickId));
它的表演undefined
,任何人都可以找到我一个解决方案
在这里完整的代码
function udatefetchPagedata() {
$.ajax({
url: syncPageURL,
dataType: "json",
success: function(data) {
console.log("The server returned " + data.length + " changes that occurred after ");
for (var ci in data) {
alert(findPageID(data[ci].pid))
//if(findPageID(data[ci].pid))
//{
//callback(data);
//insertPage(data[ci].pid, data[ci].ptitle, data[ci].pcontent, data[ci].page_slug, data[ci].porder, data[ci].pagepub, data[ci].mobicon, data[ci].mobborder, data.length);
//setLastSyncPageDevice();
//}
}
},
error: function(model, response) {
//alert(response.responseText);
}
});
}
您应该添加返回 db.transaction
对象以及函数中的 tx.executeSql
,因此,在您的功能调用之前添加返回
function findPageID(pickId)
{
return this.db.transaction(function(tx){
return tx.executeSql("SELECT pid FROM page WHERE pid="+pickId, [], function(tx, result) {
if(result) {
if(result.rows.length > 0){
return false;
}
else
{
return true;
}
}
else{
return false;
}
})
})
}
我假设您的查询代码在没有错误的情况下运行并获得预期结果!
function findPageID(pickId) {
return new Promise((resolve, reject) => {
this.db.transaction(function(tx) {
tx.executeSql('SELECT pid FROM page WHERE pid=' + pickId, [], function(tx, result) {
if (result) {
if (result.rows.length > 0) {
resolve(false);
} else {
resolve(true);
}
}
});
});
});
}
并将其称为findPageID(pickId).then(flag => console.log(flag));
,或者如果您喜欢回调
function findPageID(pickId, cb) {
this.db.transaction(function(tx) {
tx.executeSql('SELECT pid FROM page WHERE pid=' + pickId, [], function(tx, result) {
if (result) {
if (result.rows.length > 0) {
return cb(false);
} else {
return cb(true);
}
}
});
});
}
并将其称为findPageID(pickId, (flag) => console.log(flag));