Good Day, I am new to the node red environment. The project at hand is a Smart Vending machine which is for my final year project. I have managed to get a bit done on my own by reading up and using advice from the forums. Currently I am struggling to correctly read data from my DB in order to display and use those values in other functions.
As you can see above I have a table populated with data , I require to retrieve the INT values from the Price column but when I do that I receive a the full payload object as "[{ Price: 20 }]" , i tried using the split function but best I got out was "20}]" but in a string format.
The topic request to the DB is " select Price from DB where ID == 1" which is working but as stated above its not returning just the INT value as required. Also i would like to store this value and compare it to the monetary amount the user will be required to insert into the machine.
I have tried everything with my given abilities to no avail, any help or recommendations would be highly appreciated.
You don't split the values, that string you showed is JSON - use the JSON node to convert the JSON to a JS object then simply access msg.payload[0].Price
Trust me, spend 10 mins in that section of the very helpful extensive documentation - it will teach you about these things.
I don't think the sqlite node should return a string "[{ Price: 20 }]", I would have expected it to return the array itself [{ Price: 20 }]. If you feed it into a debug node you will see whether it is a string or an array. If it is already an array then you won't need the JSON node to convert it from string to array.
Good point @teladia is that string coming straight out of the sqlite node? If so which have you installed node-red-node-sqlite or one of the other sqlite nodes?
Thanks for the feedback, I did give that a read and it definitely gave me a better understanding of the messages and its properties.
Yes I forgot to mention that it was passed through a JSON node before going into the split node. I have tried the above with and without using the JSON node before feeding into my function. I am however receiving the following error : "Function tried to send a message of type number"
From that error I take it that the function is actually just receiving the INT value of 20 but doesn't like that. Could you please explain why that is , or am I going about it wrongly?
Sorry for that, as I stated to Steve I forgot to mention that I passed the data through a JSON node first , so that would explain the msg received. The SQLite is the original and does pass the proper object through. Thanks!
I managed to used a change node to get the INT value straight out and store it as a flow by using the msg.payload[0].Price as you stated.
I will continue to see if I can create a function to compare that value against the users input amount.
Thanks
