i am new in node.js and postgresql. am allready connected with postgres db and execute some test code. after am going to use prepared statements.am create a sample login script. if user exist it return username else return message "invalid username or password". if username and password is correct,it return username. but no data will present , then could not return message. my openion is that , the control will crashed after executing cliend.end() function.
this is my code
UserLogin.get = function(userName, callBack) {
pg.connect(pgConString, function(err, client, done) {
if (err) {
callBack("DB connection failed. " + err, null);
return;
}
var selectQuery="SELECT * from " + TABLE + " WHERE userName=($1)";
var query=client.query({
text:selectQuery,
values:[userName],
name:"selectQuery"});
query.on("error", function (error) {
callBack("DB fetch failed. Error Message: " + err, null);});
query.on('row', function(row) {
callBack(null, row);});
query.on("end", function (result) {
client.end();
return;
});
});
}
if row is empty, not return to callback. if row_result is not empty, its working fine.. How...???? any idea...???
finally i got the answer. thanks for u r supports
UserLogin.get = function(userName, callBack) {
pg.connect(pgConString, function(err, client, done) {
if (err) {
callBack("DB connection failed. " + err, null);
return;
}
var selectQuery="SELECT * from " + TABLE + " WHERE userName=($1)";
var query=client.query({
text:selectQuery,
values:[loginId],
name:"selectQuery"});
query.on("error", function (error) {
callBack("DB fetch failed. Error Message: " + err, null);return;});
query.on('row', function(row,result) {
result.addRow(row);
});
query.on('end', function (result) {
callBack(null,result.rows);
client.end();
return;
});
});
}
in my old code, callback will be called everytime the query fetches 1 row from the database. am just changed the logic
Your code
query.on('row', function(row) {
callBack(null, row);
});
means that the callback will be called everytime the query fetches 1 row from the database. In the case when the query has 0 results, the callback will never be called.
Related
my data structure schema is like
users(
id serial primary key,
data json
);
I want to update data key.
I'm using node-postgres library and So far I have tried something like this:
pg.connect(process.env.DATABASE_URL, function(err, client, done) {
var queryString = "UPDATE users SET data =" + myNewJsonData + " WHERE id = " + userIdToEdit + ";";
client.query(queryString, function(err, result) {
done();
if (err) {
res.send("Failed to update user data ");
throw err;
} else {
res.send("Successfully updated user data!! ");
}
});
});
this is not working, I'm getting error invalid input syntax for type json
Can anyone help, Thanks.
So it was a syntax error, All I had to do stringfy json data and put that in 'quotes'
pg.connect(process.env.DATABASE_URL, function(err, client, done) {
var newJsonDataStringyfied = JSON.stringify(myNewJsonData)
var queryString = "UPDATE users SET data = '" + newJsonDataStringyfied + "' WHERE id = " + userIdToEdit + ";";
client.query(queryString, function(err, result) {
done();
if (err) {
res.send("Failed to update user data ");
throw err;
} else {
res.send("Successfully updated user data!! ");
}
});
});
I'm trying to check user name and password (which I'm getting via post) and if it correct, response with the user page.
for some reason I'm always fail (although I know the user and pass are correct):
app.post("/loginDetials", function(req, res) {
var userName = req.body.userName;
var passw = req.body.passw;
if(req.body.userName && req.body.passw)
{
console.log('Checkking userName: ' + userName + ' password: ' + passw);
var db = new sqlite3.Database('usersDataBase');
db.all("SELECT * FROM usersTable where (userName==?) AND (password==?)", function(err,rows){
if (err)
{
console.log('Error: ' + err);
}
else
{
rows.forEach(function (row) {
console.log('Login Succ')
res.sendFile('userSite.html', {root: __dirname })
});
}
});
db.close();
}
console.log('Login Fail')
res.sendFile('main.html', {root: __dirname })
});
What am I doing wrong ?
And is this the correct way to verify details ?
You have some async code and other flow problems with your code.
You are actually sending twice your response and you close the database before the query has been executed.
Problem with calling twice res.send
var userName = req.body.userName;
var passw = req.body.passw;
if(req.body.userName && req.body.passw) {
/** Some logic */
res.send(...);
}
res.send(...);
So you see res.send is called twice if you have supplied userName and passw query.
Problem with async closing db connection
In JavaScript we have async functions which don't stop the flow of the program and rely on callbacks. db.all is such a function, which you call and immediately after that you call db.close()
var db = new sqlite3.Database('usersDataBase');
db.all("SELECT * FROM usersTable where (userName==?) AND (password==?)", function(err,rows){
// You need to move your `db.close()` inside the callback
// in order to close the database when the query has ended
db.close();
if (err)
{
console.log('Error: ' + err);
}
else
{
rows.forEach(function (row) {
console.log('Login Succ')
res.sendFile('userSite.html', {root: __dirname })
});
}
});
// db.close(); <-- commented out.
I have a nodeJS application using the mssql driver to interact with my SQL database. I want to have a single function to get a value from a database, however, on first use, the table won't exist, so if there is a specific error, I want to call my createValue() function. The code below works, but I have to call it twice to get the value. Basically, if the condition in the .catch is met, I would like to call the Request again. Is there a neat way of doing this?
var value;
new sql.Request().query('select * from _table')
.then(function (recordset) {
value = recordset;
})
.catch(function (err) {
console.log("Query Error: " + err);
if (err.message == "Invalid object name '_table") {
createValue();
}
})
Update:
I now have the following function, but how should I best get it to return recordset?
function getData() {
sql.connect("mssql://username:password#localhost/mytestdatabase").then(function () {
return new sql.Request().query('select * from _table')
.then(function (recordset) {
console.log(recordset); // <-- THIS IS WHAT I WANT TO RETURN
})
.catch(function (err) {
console.log("Query Error: " + err);
if (err.message == "Invalid object name '_table") {
updateValue();
return getData();
}
return null;
})
}).catch(function (err) {
console.log("Connection Error: " + err);
})
};
You can wrap it in a function, which you can then call recursively.
I'm assuming createValue() is synchronous.
function getData(){
return new sql.Request().query('select * from _table')
.catch(function (err) {
if (err.message == "Invalid object name '_table") {
createValue();
return getData();
}
throw err;
});
}
...
var resultsetPromise = getData();
resultsetPromise.then( function(resultset){
// do something with your data
}).catch( function(err){
console.log("Query Error: " + err);
});
I wrote the following module which connects to postgresql or SQLServer depending a the Type var value:
exports.GetQueryResult = function (type, Name,con,callback) {
var sql='';
if (Type ='PG') {
sql=sql + ' SELECT …………..';
pg.connect(con, function(err, client, done) {
if(err) {
console.log("Error :" + err);
return callback(err);
}
client.query(sql,[Name], function(err, Result) {
if(err) {
console.log("Error: " +err);
return callback(err);
}
return callback(null,Result);
done();
});
});
}
else
{
sql=sql + ' SELECT …..';
sql.open(con, function (err, conn,done) {
if (err) {
console.log("Error :" + err);
return callback(err);
}
conn.queryRaw(sql,Name, function (err, Result) {
if (err) {
console.log("Error ejecutando la consulta. Error: " +err);
return callback(err);
}
callback(null,Result);
done;
});
});
}
};
I call this function from:
var MultiBD = require('./MultiBD.js');
var LayerType=['PG','SQL','PG'];
var con=’’;
for (var i=1; i<=Layers.length; i++) {
if (Layers[i-1]!=undefined){
con=MultiBD.conexion(LayerType [i-1],server,BD);
MultiBD.GetQueryResult(LayerType[i-1], Name[i-1],con,
function (err,Result){
console.log('Result : ' + Result.rows.length);
}
);
}
}
The results are:
Result : 111
Result : 2888
Result : 5
I get three query results. The first one returns 111 rows, the second one 2888 and the third one 5.
What i need is to get only one unique result with all the 3004 rows (111+2888+5).
Regards,
You'll need some flow control to wait until all 3 methods have completed their DB calls before printing their results. There are packages for this, either of the callback variety or Promises.
Here is an example using the async package (which is of the callback variety of flow-control):
var async = require('async');
var totalResults = 0;
async.each( Layers, function eachMethod( layer, eachCb ){
var con = MultiBD.conexion(layer,server,BD);
MultiBD.GetQueryResult(LayerType[i-1], Name[i-1],con, function (err,Result) {
if( err ) return eachCb( err );
totalResults += Result.rows.length;
eachCb( null );
} );
}, function finalEach( eachErr ){
if( eachErr ) console.log( "There was an error. " + eachErr );
else console.log( "Result: " + totalResults );
});
In this call, a method (the eachMethod) is called on every item in the array. The results are stored in a shared variable. When all items have completed, the finalEach method is called. Here errors have bubbled up (which you can choose to check or not) and all calls have completed, so we can simply print the value of the shared variable.
I am quite newbie with node.js. What i am trying to achieve is the following:
Connect to my postgresql database and get info of a place (id, coordinates).
call a weather api and get the info of that spot using the coordinates obtained in the previous step.
Insert the returned json in the database. I get 8 hourly objects, with the weather info every 3 hours (0,3,6,9,12,15,18,21). I need to iterate through this objects and the store them in 8 records in the database.
I wrote the following code:
app.get('/getapi', function(req, res){
var json_bbdd;
//------------ BBDD CONNECTION----------------
var pg = require('pg');
var conString = "postgres://postgres:postgres2#localhost/places";
var client = new pg.Client(conString);
client.connect(function(err) {
if(err) {
console.log('could not connect to postgres');
}
client.query('SELECT * from places where id=3276', function(err, result) {
if(err) {
console.log('error running query');
}
json_bbdd=result.rows[0];
var coords = JSON.parse(json_bbdd.json).coordinates;
var id = json_bbdd.id;
var input = {
query: coords[1] + ',' + coords[0] ,
format: 'JSON',
fx: '',
callback: 'MarineWeatherCallback'
};
var url = _PremiumApiBaseURL + "marine.ashx?q=" + input.query + "&format=" + input.format + "&fx=" + input.fx + "&key=" + _PremiumApiKey + "&tide=yes";
$.ajax({
type: 'GET',
url: url,
async: false,
contentType: "application/json",
dataType: 'jsonp',
success: function (json) {
var date= json.data.weather[0].date;
for (var i=0; i < 8; i++){
var hourly = json.data.weather[0].hourly[i];
var time= hourly.time;
client.query('INSERT into parte (id, date, time) VALUES($1, $2, $3)', [id, date, time],
function(err, result) {
if (err) {
console.log(err);
} else {
console.log('row inserted: ' + id + ' ' + time);
}
});
} // FOR
},
error: function (e) {
console.log(e.message);
}
});
client.end();
});
});
});
The steps 1 and 2 are performed perfectly. The third step, on the other hand, does nothing and it doesn't even throw an error.
I read in this post: node-postgres will not insert data, but doesn't throw errors either that using async module could help but i have no idea how to rewrite the code. I need some help.
Regards,
Aitor
I didn't test your snippet, I can only help you with things which looks bad to my eyes.
It is better not to use jQuery on node server. There is excellent library called request to do remote http requests.
You should better handle database errors because in your example your code will continue after DB error.
You are calling client.end() too early and at the time when you try to insert data to the database a connection is already closed. You have to move client.end() at the end of success and error functions and wait to all callbacks are done.
I think it is also better to use connection pool instead of Client.
You can possibly use JSON type in PostgreSQL to avoid serializing/deserializing JSON data in your code.
Here is revised example(untested). I didn't replace jQuery here, some minor tweaking included.
var pg = require('pg');
var conString = "postgres://postgres:postgres2#localhost/places";
app.get('/getapi', function(req, res, next){
var json_bbdd;
//------------ BBDD CONNECTION----------------
pg.connect(conString, function(err, client, done) {
if(err) {
// example how can you handle errors
console.error('could not connect to postgres');
return next(new Error('Database error'));
}
client.query('SELECT * from places where id=3276', function(err, result) {
if(err) {
console.error('error running query');
done();
return next(new Error('Database error'));
}
json_bbdd = result.rows[0];
var coords = JSON.parse(json_bbdd.json).coordinates;
var id = json_bbdd.id;
var input = {
query: coords[1] + ',' + coords[0] ,
format: 'JSON',
fx: '',
callback: 'MarineWeatherCallback'
};
var url = _PremiumApiBaseURL + "marine.ashx?q=" +
input.query + "&format=" + input.format +
"&fx=" + input.fx + "&key=" +
_PremiumApiKey + "&tide=yes";
$.ajax({
type: 'GET',
url: url,
async: false,
contentType: "application/json",
dataType: 'jsonp',
success: function (json) {
var date = json.data.weather[0].date;
var callbacks = 0;
for (var i=0; i < 8; i++) {
var hourly = json.data.weather[0].hourly[i];
var time= hourly.time;
client.query(
'INSERT into parte (id, date, time) VALUES($1, $2, $3)',
[id, date, time],
function(err, result) {
if (err) {
console.log(err);
} else {
console.log('row inserted: ' + id + ' ' + time);
}
callbacks++;
if (callbacks === 8) {
console.log('All callbacks done!');
done(); // done(); is rough equivalent of client.end();
}
});
} // FOR
},
error: function (e) {
console.error(e.message);
done(); // done(); is rough equivalent of client.end();
return next(new Error('Http error'));
}
});
});
});
});
Ok, now cam up with another problem...i was doubting of creating a new post but i think that maybe could have relation with the previous post.
The aim is to read from the database instead of one place 3 places and do the same process than before for each one.
The code is as follows (with the changes proposed by ivoszz):
app.get('/getapi', function(req, res, next){
//------------ BBDD CONNECTION----------------
pg.connect(conString, function(err, client, done) {
if(err) {
// example how can you handle errors
console.error('could not connect to postgres',err);
return next(new Error('Database error'));
}
client.query('SELECT * from places where id>3274 and id<3278', function(err, result) {
if(err) {
console.error('error running query',err);
done();
return next(new Error('Database error'));
}
var first_callback = 0;
for (var y=0; y<result.rows.length; y++) {
var coords = JSON.parse(result.rows[y].json).coordinates;
var id = result.rows[y].id;
var input = {
query: coords[1] + ',' + coords[0] ,
format: 'JSON',
fx: ''
};
var url = _PremiumApiBaseURL + "marine.ashx?q=" + input.query + "&format=" + input.format + "&fx=" + input.fx + "&key=" + _PremiumApiKey;
request(url, function(err, resp, body) {
body = JSON.parse(body);
if (!err && resp.statusCode == 200) {
var date = body.data.weather[0].date;
var callbacks = 0;
for (var i=0; i < 8; i++) {
var hourly = body.data.weather[0].hourly[i];
client.query(
'INSERT into parte (id, date, time) VALUES($1, $2, $3)',
[id, date, hourly.time],
function(err, result) {
if (err) {
console.log(err);
} else {
console.log('row inserted: ' + id + ' iteration ' + i);
}
callbacks++;
if (callbacks === 8) {
console.log('All callbacks done!from id '+id);
//done(); // done(); is rough equivalent of client.end();
//res.send("done");
}
});
} // FOR
}
else { // if the API http request throws an error
console.error(err);
done(); // done(); is rough equivalent of client.end();
return next(new Error('Http API error'));
}
}); // REQUEST API URL
first_callback++;
if (first_callback === result.rows.length-1) {
console.log('All global callbacks done!');
done(); // done(); is rough equivalent of client.end();
res.send("done");
}}
}); // SELECT from pg
}); // CONNECT to pg
}); // app.get
I don't know why it tries to insert the id=3277 three times instead of inserting id=3275, id=3276 and then id=3277... what it does instead is: it inserts the first 8 records ok the first time (id=3277), but then it throws an error saying that the records are already inserted (primary key=id,date,time) with id 3277...
It seems that first does the 3 iterations of the first FOR and then does the 3 iteration of the second FOR but with the info of the last iteration(place). I can't understand it very well...