CSV

#  What's the CSV node in Node-RED used for?

The CSV node in Node-RED is used for processing comma-separated values (CSV) data. It allows you to either convert a CSV string into a JavaScript object or transform an object into a CSV string. This capability makes it extremely useful for reading and writing data in a tabular format.

#  Use Case: Calculating Energy Consumption

Suppose you have a CSV file that details the energy consumption of various manufacturing stations in a factory. The file includes the station name, the month, and the total electricity consumed. You want to add a new column that displays the number of parts produced per station, based on the assumption that each part consumes a specific amount of electricity in addition to the machine's base electricity consumption.

CSV Input:

Station,Month,Consumption
Rio,January,4000
New York,January,1000
Tokio,January,3000

#  Flow

Node Documentation

Converts between a CSV formatted string and its JavaScript object representation, in either direction.

Inputs

payloadobject | array | string
A JavaScript object, array or CSV string.

Outputs

payloadobject | array | string
  • If the input is a string it tries to parse it as CSV and creates a JavaScript object of key/value pairs for each line. The node will then either send a message for each line, or a single message containing an array of objects.
  • If the input is a JavaScript object it tries to build a CSV string.
  • If the input is an array of simple values, it builds a single line CSV string.
  • If the input is an array of arrays, or an array of objects, a multiple-line CSV string is created.

Details

The column template can contain an ordered list of column names. When converting CSV to an object, the column names will be used as the property names. Alternatively, the column names can be taken from the first row of the CSV.

When converting to CSV, the columns template is used to identify which properties to extract from the object and in what order.

If the columns template is blank then you can use a simple comma separated list of properties supplied in msg.columns to determine what to extract and in what order. If neither are present then all the object properties are output in the order in which the properties are found in the first row.

If the input is an array then the columns template is only used to optionally generate a row of column titles.

If 'parse numerical values' option is checked, string numerical values will be returned as numbers, ie. middle value '1,"1.5",2'.

If 'include empty strings' option is checked, empty strings will be returned in result, ie. middle value '"1","",3'.

If 'include null values' option is checked, null values will be returned in result, ie. middle value '"1",,3'.

The node can accept a multi-part input as long as the parts property is set correctly, for example from a file-in node or split node.

If outputting multiple messages they will have their parts property set and form a complete message sequence.

If the node is set to only send column headers once, then setting msg.reset to any value will cause the node to resend the headers.

Note: the column template must be comma separated - even if a different separator is chosen for the data.