Querying MySQL with JS Object returning [object Object] as table name

Question

I'm building a program that queries MySQL databases, gets the tables, fields, field data types, and entries and returns it as a single object to be later used to view the MySQL data as a table.

This is what the built object will look like:

    {
    `Table_Name`: {
        Title: `Table_Name`,
        Fields: {
            `Field Name`: `Datatype`
        },
        RowData: []
    }

}

The query to get the tables is fine, however the query to get the row data isn't. The query function looks like this:

    function getRows(){

        let secondpromises = [];

        secondpromises.push(
            new Promise((resolve, reject) => {
                for(x in Tables){
                    Connect_SQL(SQLcreds, w_newSconn, (conn) => {
                        conn.query(`SELECT * FROM ${Tables[x]}`, (err, results) => {
                            if(err){
                                console.log(err);
                                reject(err);
                            }else{
                                for(r in results){

Tables[`${Tables[x].Title}`].RowData.push(results[r]);
                                }
                                resolve(results);
                            }
                        });
                    });

                    if(x == Tables.length - 1){
                        Promise.all(secondpromises).then(() => {
                            if(w_newSconn){
                                w_newSconn.close();
                                w_newSconn = null;
                            }
                            console.log(Tables);
                        });
                    }
                }
            })
        );
    }

The error is coming from conn.query(). It is throwing an error stating there is an error in my SQL syntax at:

SELECT * FROM [object Object]

I understand the reason why and I'm sure there is a way to resolve this through JSON.Stringify() but there must be a simpler way. I have already tried creating a variable like so:

let objArray = Object.keys(Tables)

But it still returned [object Object], any help would be appreciated.

i doubt this is possible.. MySQL normally does not allow preparing table and or column names in prepared statements.. Not sure if there is a translating layer in Node.js which makes this possible without SQL injection problems. — Raymond Nijland, Oct 23 '18 at 15:02
After Googling i found that it was possible in Node.js.. Possible duplicate of [Nodejs-Mysql Query table name as a variable](https://stackoverflow.com/questions/45422100/nodejs-mysql-query-table-name-as-a-variable) — Raymond Nijland, Oct 23 '18 at 15:06
Inserting a dynamic variable into a query isn't the issue. The problem I am running into is returning the name of the key instead of an object. I added an array that stores the keys and is now coming back with keys[n] being undefined. — Brandon Carr, Oct 23 '18 at 15:26
The value of `Tables[x]` is an object, not a table name. The table name is presumably in a property, so that should be something like `Tables[x].name` (replace `name` with the actual name of the property that contains the table name). — Barmar, Oct 23 '18 at 15:44

score 0 · Answer 1 · answered Oct 23 '18 at 15:46

Tables[x] is an object. You need to get the table name from it.

conn.query(`SELECT * FROM ${Tables[x].Title}`, (err, results) => {

It also looks like the property name is the same as the title, so you can do:

conn.query(`SELECT * FROM ${x}`, (err, results) => {

score 0 · Answer 2 · answered Oct 23 '18 at 16:06

I ended up creating a variable in the loop

let table = keys[x]

and that did the trick, for whatever reason ${keys[x]} was returning undefined but the variable returned the table name. Theoretically I could have changed the for loops to a

for(x in Tables)

and x would have returned the title so I may go back and rewrite it that way. Thank you.

Querying MySQL with JS Object returning [object Object] as table name

2 Answers2