I'm trying to create a json file and write to it.
My code looks like this:
def save_as_json(object) f = File.new('file.json') f.puts(object.to_json, 'w') f.close end save_as_json({'name'=>'fred'}) The problem is, I get the following error when I run it:
:15:in `initialize': No such file or directory @ rb_sysopen - file.json (Errno::ENOENT) I'm asking Ruby to create the file but it's complaining that it doesn't exist! What is the correct way to create and write to a file?
You just need to open the file using the 'w' mode like this:
f = File.new('file.json', 'w') You want to determine the mode based on what you plan to do with the file, but here are your options:
"r" Read-only, starts at beginning of file (default mode).
"r+" Read-write, starts at beginning of file.
"w" Write-only, truncates existing file to zero length or creates a new file for writing.
"w+" Read-write, truncates existing file to zero length or creates a new file for reading and writing.
"a" Write-only, each write call appends data at end of file. Creates a new file for writing if file does not exist.
"a+" Read-write, each write call appends data at end of file. Creates a new file for reading and writing if file does not exist.
File creation defaults to read mode, so trying to use a filespec that does not exist will result in an error:
2.3.0 :001 > f = File.new 'foo' Errno::ENOENT: No such file or directory @ rb_sysopen - foo You need to specify 'w':
2.3.0 :002 > f = File.new 'foo', 'w' => #<File:foo> That said, there are easier ways to write to files than to get a file handle using File.new or File.open. The simplest way in Ruby is to call File.write:
File.write('file.json', object.to_json) You can use the longer File.open approach if you want; if you do, the simplest approach is to pass a block to File.open:
File.open('file.json', 'w') { |f| f << object.to_json } This eliminates the need for you to explicitly close the file; File.open, when passed a block, closes the file for you after the block has finished executing.
File.write( "file.json", object.to_json ). This will truncate an existing file or create a new file if one doesn't exist, write the contents to it and close the file.