csv

--- language: en layout: page title: "Reading data from a source" date: 2013-03-31T21:12:03.752Z comments: false sharing: false footer: false navigation: csv github: https://github.com/wdavidw/node-csv-parser --- The `csv().from` property provides functions to read from an external source and write to a CSV instance. The source may be a string, a file, a buffer or a readable stream. You may call the `from` function or one of its sub function. For example, here are two identical ways to read from a file: ```javascript csv.from('/tmp/data.csv').on('data', console.log); csv.from.path('/tmp/data.csv').on('data', console.log); ``` <a name="from"></a> `from(mixed)` ------------- Read from any sort of source. It should be considered as a convenient function which will discover the nature of the data source to parse. If it is a string, then if check if it match an existing file path and read the file content, otherwise, it treat the string as csv data. If it is an instance of stream, it consider the object to be an input stream. If is an array, then for each line should correspond a record. Here's some examples on how to use this function: ```javascript csv() .from('"1","2","3","4"\n"a","b","c","d"') .on('end', function(){ console.log('done') }) csv() .from('./path/to/file.csv') .on('end', function(){ console.log('done') }) csv() .from(fs.createReadStream('./path/to/file.csv')) .on('end', function(){ console.log('done') }) csv() .from(['"1","2","3","4","5"',['1','2','3','4','5']]) .on('end', function(){ console.log('done') }) ``` <a name="from.options"></a> `from.options([options])` ------------------------- Update and retrieve options relative to the input source. Return the options as an object if no argument is provided. * `delimiter` Set the field delimiter, one character only, defaults to comma. * `rowDelimiter` String used to delimit record rows or a special value; special values are 'auto', 'unix', 'mac', 'windows', 'unicode'; defaults to 'auto' (discovered in source or 'unix' if no source is specified). * `quote` Optionnal character surrounding a field, one character only, defaults to double quotes. * `escape` Set the escape character, one character only, defaults to double quotes. * `columns` List of fields or true if autodiscovered in the first CSV line, default to null. Impact the `transform` argument and the `data` event by providing an object instead of an array, order matters, see the transform and the columns sections for more details. * `flags` Used to read a file stream, default to the r charactere. * `encoding` Encoding of the read stream, defaults to 'utf8', applied when a readable stream is created. * `trim` If true, ignore whitespace immediately around the delimiter, defaults to false. * `ltrim` If true, ignore whitespace immediately following the delimiter (i.e. left-trim all fields), defaults to false. * `rtrim` If true, ignore whitespace immediately preceding the delimiter (i.e. right-trim all fields), defaults to false. Additionnaly, in case you are working with stream, you can pass all the options accepted by the `stream.pipe` function. <a name="from.array"></a> `from.array(data, [options])` ------------------------------ Read from an array. Take an array as first argument and optionally some options as a second argument. Each element of the array represents a csv record. Those elements may be a string, a buffer, an array or an object. <a name="from.string"></a> `from.string(data, [options])` ------------------------------- Read from a string or a buffer. Take a string as first argument and optionally an object of options as a second argument. The string must be the complete csv data, look at the streaming alternative if your CSV is large. ```javascript csv() .from( '"1","2","3","4"\n"a","b","c","d"' ) .to( function(data){} ) ``` <a name="from.path"></a> `from.path(path, [options])` ---------------------------- Read from a file path. Take a file path as first argument and optionally an object of options as a second argument. <a name="from.stream"></a> `from.stream(stream, [options])` -------------------------------- Read from a stream. Take a readable stream as first argument and optionally an object of options as a second argument.