json-file-object

json-file-object

A mockup of a db for a single "JSON"-able object, periodically stored in a file so it can be recovered after restart.

To install, do

> npm install json-file-object

Example

var json_file_object = require("json-file-object");
var my_obj = json_file_object();

The reference stored in variable my_obj is saved to the file file_object.json every 5 secs. If the file exists, the object under the reference is initialized with the JSON parsed content of the file, if not it is initialized to {}.

The above defaults (for the file name, the interval, or the initial value) can be specified by the parameters passed to the constructor function returned by json_file_object = require("json-file-object"). I.e., var my_obj = json_file_object() really means:

var my_obj = json_file_object({value:{}, file:"json_file_object.json", saveEverySecs:5, forceNew:false});

If flag forceNew is set, the old content of the file is ignored and the initial value of the returned object is set by the first argument.

The generator function returned by require("json-file-object"), called here json_file_object, has following methods:

• json_file_object.stop(obj) - stops recording obj to its file
• json_file_object.stopAll() - stops all recordings
• json_file_object.erase(obj) - stops recording obj and erases the corresponding file
• json_file_object.eraseAll() - stops all recordings and erases all corresponding files

For more info, look into the code index.coffee and tests test.coffee, re_test.coffee, which are probably shorter than that document.

Warnings!

You can not reassign a new reference to my_obj and hope that the new value will be persisted. For example, if you do

my_obj = ["Hey"];

the old reference kept by my_obj is lost, so any change to my_obj, such as

my_obj.push("Ho");

will not be persisted (because the value under the old reference is being persisted). The logic here is somehow similar to exports and module.exports.

Also, notice that in order to properly terminate the node process using json-file-object you will need to stop "persisting", e.g., by calling json_file_object.stopAll().