#ecsv 0.3
2011 (c) Nicolas R Dufour [email protected]
ecsv is a simple Erlang CSV parser able to read a file or string and sending back to an erlang process events when a line is parsed.
ecsv is under MIT. See NOTICE file for more details.
##Requirements
- Erlang/OTP R13/R14
- GNU Make
##Design
Ecsv is using a stateful parser in which you have to:
- create a initial state with options and a processing function
- provide a flow of character to the main parsing function ([parse_with_character])
##How to use it
Create a function that will accept 2 arguments:
- an element which can be
- {eof} if the flow had ended
- {newline, NewLine} for each parsed line
- a current state (defaulted to [])
Example: how to count the lines:
MyFun = fun(_NewLine, Counter) ->
% NewLine contains an array of strings
Counter 1.
Then call ecsv with the default state set to 0
:
{ok, IoDevice} = file:open("/path/to/my.csv", [read]),
{ok, FinalCounter} = ecsv:process_csv_file_with(IoDevice, MyFun, 0)
FinalCounter
will have the number of parsed lines.
Take a look at the examples in the directory examples
. A basic benchmark accepting one argument as the csv filename will parse it and display the number of parsed lines.
##Notes
This parser is based on the blog post written by Andy Till located here http://andrewtill.blogspot.com/2009/12/erlang-csv-parser.html.
This parser supports well formed csv files which are
- a set of lines ending with a
\n
- each line contains a set of fields separated with a comma (
,
) - each field value can be enclosed with single (
'
) or double quote ("
) - each field value can be empty
- any
\r
is ignored
Example:
SC_Group_ID,SC_Group_Desc,SC_GroupCommod_ID,SC_GroupCommod_Desc,SC_Geography_ID,SortOrder,SC_GeographyIndented_Desc,SC_Commodity_ID,SC_Commodity_Desc,SC_Attribute_ID,SC_Attribute_Desc,SC_Unit_ID,SC_Unit_Desc,Year_ID,SC_Frequency_ID,SC_Frequency_Desc,Timeperiod_ID,Timeperiod_Desc,Amount
2,"Supply and use",9,"Barley",1,0.800,"United States",1,"Barley",34,"Imports, trade year",7,"1,000 metric tons",1960,3,"Annual",114,"MY Oct-Sep",248
2,"Supply and use",9,"Barley",1,0.800,"United States",1,"Barley",34,"Imports, trade year",7,"1,000 metric tons",1961,3,"Annual",114,"MY Oct-Sep",326
Please note:
- This parser has no failsafe mechanism if the file is badly formed!
But the line
a,,,,,\n
is perfectly fine. - This parser doesn't allow a return (
\n
) in a field value!