Develop Reference

Seeking proper way to use the get() method of INDEXEDDB data store

I am attempting to use a simple indexeddb 'get' method to retrieve a keyed record from an existing data store. For some reason that i have been unable to find, though the result of my 'get' request is 'successful', the returned value is 'undefined'.
The code below is called from an event listener that is fired when the user clicks on a button in a row of a table, indicating the user wants details on that particular row. Each row in the table represents a record in the indexeddb data store that has already been created. There are 8 values of interest in each row, but only 3 are displayed in my html table. I am simply attempting to access the row in the data store to get all 8 values in order to pass them along to the next process.
The following code is called from an event listener created on a 'Select' button for each row...
async function getGameInProgressDetails(gameID) {
try {
db = await idbConnect(DBName,DBVersion);
let tx = db.transaction(['gamesList'], 'readonly');
let gameStore = tx.objectStore('gamesList');
// I have confirmed the 'gameID' passed in is the key value that i would expect
// to retrieve the desired result.
let req = gameStore.get(gameID); // gameID comes from the selected row in the html table.
req.onsuccess = (ev) => {
console.log('Success');
let request = ev.target;
console.log(request); // returns an IDBRequest object with result: undefined and error: null.
let theGame = request.result;
console.log(theGame ); // displays 'undefined'.
}
req.onerror = (err) => {
console.warn(err);
};
} catch (e) {
console.warn(e);
}
I get the 'success' message indicating that the 'get' operation was successful, but my result is 'undefined'. Could someone please tell me if i am missing a step or if there's another way to go about this that i should look into? I've looked at a variety of tutorials and i must be overlooking something 'obvious'.

I discovered the problem with my code/approach and am answering my own question. The reason that the above code was not working was not because of my indexeddb code or logic at all.
What i discovered was that the index value that i had passed into the routine needed to be cast as an integer before the get() method call, JS was treating it as a string value. I was confused by the fact that i had checked the value in a console.log statement and it had shown the appropriate value. What i hadn't considered was how JS evaluated what type the variable value was.
For those coming later and seeing this, my final code was thus:
async function getGameInProgressDetails(gameID) {
db = await idbConnect(DBName,DBVersion);
let tx = db.transaction(['gamesList'], 'readonly');
var gameStore = tx.objectStore('gamesList');
let gameIndex = gameStore.index("gameIDIdx");
let request = gameIndex.get(parseInt(gameID)); //!! NOTE THE parseInt!!
request.onsuccess = function() {
if (request.result !== undefined) {
console.log("Games", request.result);
} else {
console.log("No such games.");
}
}

Using a variable in a WHERE clause MySQL/Node

I'm trying to make a MySQL query to filter data from a table. Effectively what I want to do is:
SELECT data FROM table WHERE column IN ?
The filter is coming from checkboxes in a form on a webpage, so I can pass an array or object fairly easily, but it'll be a varying number of parameters for the IN each time, so I can't us multiple ?. I tried making a for loop to make multiple queries concatenate the arrays that the queries returned, but I ran into scope issues with that. I also tried passing an array directly to the query, but that throws a syntax error. I'm sure there's a straightforward answer to this but I'm not sure how to do it.
Edit: source code added:
Here's where I'm at:
const filterShowQuery = `SELECT sl_Show.showId, sl_Band.BandName,
sl_Show.date, sl_Venue.venueName,
sl_Show.length, sl_Show.attendance, sl_Show.encore FROM sl_Show
JOIN sl_Band on sl_Show.BandID = sl_Band.BandId
JOIN sl_Venue on sl_Show.VenueId = sl_Venue.VenueId
WHERE sl_Band.BandName IN (?)
ORDER BY sl_Band.BandName;`;
Trying to get an array into the ? in WHERE sl_Band.BandName IN
const getShows = (req, res,next) =>{
var {bands, venues} = req.body;
var i = 0; //left over from previous attempt
var data = [];
for (b in bands){
mysql.pool.query(filterShowQuery, bands[b], (err, result) => {
if(err){
console.log('filter band error');
next(err);
return;
}
data = data.concat(result);
console.log(data); //data concatenates property and increases through for loop
})
// same action to be performed with venues once solved
// for (v in venues){
// conditions[i] = venues[v];
// i++;
console.log(data); //data is empty when logging from here or using in res
res.json({rows:data});
}
}

SECURITY WARNING!
I must to say: NEVER, NEVER PASS DATA DIRECTLY TO YOUR SQL!
If you don't know why, just google for SQL Injection. There are lots of examples on how it is done, how easily it can be done, and how to protect your application from this sort of attack.
You should always parametrize your queries. But in the very rare case which you really need to insert data concatenating a string into your sql, validate it before.
(E.g.) If it's a number, than use a Regex or some helper method to check if the value you are inserting into your SQL String is really and only a number and nothing else.
But aside that, you did not provide any source code, so it's really hard to give any help before you do that.

Node mssql: return id after SQL insertion

I am working on an integration between Mongodb and SQL Server, inserting and updating registers from MongoDb to SQL Server database with a scheduled process, using the mssql package to achieve this.
Each time a new register is inserted, I want the new row id to be retrieved back, because I need it to perform another insertions of subregisters.
I tried the following, expecting to have some information retrieved in the result of the query. The query actually inserts the row, but result is returned as undefined:
var sql = require('mssql');
var connectionConfig = 'xxxxxxxxxxxx';
var insertionQuery = 'xxxxxxxxxxxx';
sql.connect(connectionConfig).then(pool => {
pool
.request()
.query(insertionQuery);
}).then(result => {
//I expect 'result' to have information of the inserted row, but it comes undefined instead
cosole.log(result);
}).catch(err => {
console.err(err);
});
I think using stored procedures may work around this, but I just want to avoid using a stored procedure for simple inserts.
Does anyone knows how to have the new row id back after insertion?
EDIT
I did include OUTPUT SCOPE_IDENTITY() in my SQL statement - my query now looks like:
INSERT INTO TABLE (columns...)
OUTPUT SCOPE_IDENTITY()
VALUES (values...)
If I run the query in my SQL Server Management Studio, it works just fine and I got my new row id returned, but when running the query through the mssql package's query method, result is returned like this:
[ { '': null } ]

I quote from node-mssql insert returning undefined recordset:
INSERT statement doesn't return a recordset so recordset is
undefined. Please see this section of the docs to learn more
about how to get number of affected rows.
An option to solve this is to add a SELECT statement after your INSERT and ask for SCOPE_IDENTITY() or ##IDENTITY. That will get you the ID of the last inserted objects, i.e.:INSERT INTO table (...) VALUES (...); SELECT SCOPE_IDENTITY() AS id;

If anyone comes having problems with GUID, since you cannot set it as an Identity column, you must do something like:
const result = await pool
.request()
.input('orgName', sql.VarChar, orgName)
.input('tier', sql.Int, tier)
.input('status', sql.Int, status)
.input('createDate', sql.Date, new Date())
.input('statusChangeDate', sql.Date, new Date())
.query(`INSERT INTO app.Organizations (OrgName,
Tier, Status, CreateDate, StatusChangeDate)
OUTPUT inserted.OrgID
VALUES (#orgName, #tier, #status, #createDate, #statusChangeDate);
`)
Where the orgID is the auto generated GUID. Also don't follow my new Date() example as it inserts the date as tomorrow... I need to fix that.

Unable to access the variable in NodeJs function

I am using NodeJS postgresql client to fetch some data loop through it and give an output. I'm using ExpressJS together with postgresql client.
This is my code
var main_data = some array of data
var user_info = {}
for (var key in result.rows) {
var user = main_data[key].user
client.query('SELECT name,age,address FROM users WHERE user_id = $1 LIMIT 1;' , [user], function(queryErr, result){
var return_data = result.rows[0]
user_info.name = return_data.name
user_info.gender = return_data.gender
user_info.address = return_data.address
main_data[key].user_info = user_info
})
}
done()
res.json(main_data)
return
However when I run this code I don't get a proper output. The userinfo is not pushed to the main_data. It just outputs main_data variable just as the beginning of the code.
It is not simple as the suggested duplicate
Because the function sits inside a for loop so I can't just make the response call once the function is done. I have to wait till the whole loop is finished which may be 1000+ of loops to finish before I can make the response call.
So tell me how can I achieve it.
What am I doing wrong and how can fix it?
Thank you very much

I would use async.js for this, myself.
var rows = // your result.rows stuff.
function doTheQuery(item, callback){
// your query logic here, calling the callback with the results
}
async.series(rows, doTheQuery, function(err){
// handle any errors
}

WebSQL return object

Can someone show me a web SQL select query that returns the results as an object rather than alerting or logging to the console.
I want to centralize my select queries rather than repeating the select / execute and process results code in the specific functions.

If we presume that the question relates to the API required under Web SQL to execute the query and obtain a result set you can proceed as shown below. I've not given much detail as the question is a tad vague and shows little evidence of homework...
Initiate a readTransaction (you did say 'query' so I'll presume "select") on an open database:
db.readTransaction(onStartTransaction); // less locking overhead with a readTransaction
The onStartTransaction function looks like this:
function onStartTransaction(tx) {
tx.executeSql(sql, params, onExecuteSqlOk, onExecuteSqlFail);
}
Just pass your sql and a [] for params if you don't need any.
Your results will be returned to your 'onExecuteSqlOk' function:
function onExecuteSqlOk(tx, result) {
//
// tx: an SqlTransaction object
// results: an SqlResultSet object
//
The goodies are in the SqlResultSet object.
it has a structure with a 'rows' property. Each row contains the fields specified in the sql select statement.
var len = results.rows.length; // how many rows did we get
var firstRow = results.rows.item(0);
Thus you get an "object" back as the results from a Web Sql query. Note that the api shown is asynchronous so you will probably want to use a further callback function....