Node JS – Manipulation with files and JSON
JSON is somehow powerful. With Node JS and JSON you may build almost anything you can think of (if you have unlimited time and coffee/beer).
How about building a small console application with the following options:
Yesterday, I started to build a console application, similar to this one, but still not the same and in Java Script. The current one is running over a JSON file, making some editions with it. The program has the following features:
add enables you to add a new entry to the JSON
get gives information for the entry on a specific id
remove removes entry from the JSO
update updates entry at JSON
search searches in JSON and returns the data (the get searches only per IDs, this is more general)
load loads a new JSON variable from a file
nice prints the JSON file in a beautiful table, adjustable by the size of the variables. I have used hardcoding in the function promptNiceCommand();, which I am not proud of, but the result was quite satisfactory.
save saves the JSON variable into a file
quit quits the application
Indeed, a fully functioning application. Loading DB, editing it, searching it, displaying it and saving the results. Well, the interface is a little chabby indeed, but it works:
Here comes the code. Make sure you have “file.json” in the same dir, containing something like this to have the application running smoothly:
[{"id":"10",
"name":"Peter",
"email":"peter@bg.com"
},
{
"id":"20",
"name":"Sasho",
"email":"Sasho@bg.com"
},
{
"id":"30",
"name":"Gosho",
"email":"gosho3@bg.com"}]
Here comes the code, enjoy it responsibly :
var prompt = require('prompt');
prompt.start();
var jsonFile = [{
"id":"11000000000000",
"name":"DuckTalesCharacter",
"email":"setralalair1@bg.com"
},
{
"id":"222",
"name":"DuckTalesCharacterDui",
"email":"seir2@bg.com"
},
{
"id":"3000",
"name":"Lui",
"email":"seir3@bg.com"
}]
function promptSearchCommand(){
console.log("Please, write an element to search:")
prompt.get(['searched'], function(err, result){
var sSearchedItem = result.searched;
for (var i = jsonFile.length - 1; i >= 0; i--) {
if (sSearchedItem == jsonFile[i].id){
console.log(jsonFile[i].id);
console.log(jsonFile[i].name);
console.log(jsonFile[i].email);
main();
}
};
for (var i = jsonFile.length - 1; i >= 0; i--) {
if (sSearchedItem == jsonFile[i].name){
console.log(jsonFile[i].id);
console.log(jsonFile[i].name);
console.log(jsonFile[i].email);
main();
}
};
for (var i = jsonFile.length - 1; i >= 0; i--) {
if (sSearchedItem == jsonFile[i].MyNewName){
console.log(jsonFile[i].id);
console.log(jsonFile[i].name);
console.log(jsonFile[i].email);
main();
}
};
})
}
function promptLoadCommand(){
var jf = require('jsonfile')
var util = require('util')
var file = 'file.json'
jsonFile = jf.readFileSync(file)
console.log("A file has been loaded!")
main();
}
function promptGetCommand(){
console.log("Please, write the id to search:")
prompt.get(['id'], function(err, result){
var sSearchedItem = result.id
for (var i = jsonFile.length - 1; i >= 0; i--) {
if (sSearchedItem == jsonFile[i].id){
console.log (jsonFile[i].id);
console.log (jsonFile[i].name);
console.log (jsonFile[i].email);
}
};
main();
})
}
function promptRemoveCommand(){
console.log("Please, write the id to delete:")
prompt.get(['id'], function(err, result){
var sSearchedItem = result.id
for (var i = jsonFile.length - 1; i >= 0; i--) {
if (sSearchedItem == jsonFile[i].id){
jsonFile.splice(i,1)
}
};
main();
})
}
function promptUpdateCommand(){
console.log("Please, write the id to update:")
prompt.get(['id','MyNewName','MyNewEmail'], function(err, result){
var sSearchedItem = result.id;
for (var i = jsonFile.length - 1; i >= 0; i--) {
if (sSearchedItem == jsonFile[i].id){
jsonFile[i].name = result.MyNewName;
jsonFile[i].email = result.MyNewEmail;
main();
}
};
console.log("Wrong ID. No update generated!")
})
}
function promptMenuCommand(){
console.log(jsonFile);
main();
}
function promptAddItem(){
prompt.get(['id', 'name', 'email'], function(err, result){
console.log('Data entry confirmed');
var newID = result.id;
var newName = result.name;
var newEmail = result.email;
var objToAdd = {
"id":newID,
"name":newName,
"email":newEmail
}
jsonFile[jsonFile.length]=objToAdd;
main();
})
}
function promptSaveCommand(){
var jf = require('jsonfile')
var file = 'myData.json'
jf.writeFileSync(file, jsonFile)
console.log("A file has been saved!")
main();
}
String.prototype.repeat = function(length) {
return Array(length + 1).join(this);
};
function promptNiceCommand(){
var l1 = 0
var l2 = 0
var l3 = 0
var c1 = 0
var c2 = 0
var c3 = 0
for (var i = jsonFile.length - 1; i >= 0; i--) {
if (jsonFile[i].id.length>l1){
l1 = jsonFile[i].id.length;
}
if (jsonFile[i].name.length>l2){
l2 = jsonFile[i].name.length;
}
if (jsonFile[i].email.length>l3){
l3 = jsonFile[i].email.length;
}
}
c1 = "id".length
c2 = "name".length
c3 = "email".length
console.log("%s", "_".repeat(l1+l2+l3+14)) //14 is the sum of the added spaces and vertical lines between names
console.log("|| %s %s|| %s %s|| %s %s||", "id", " ".repeat(l1-c1), "name", " ".repeat(l2-c2),"email"," ".repeat(l3-c3))
console.log("%s", "_".repeat(l1+l2+l3+14))
for (var i = jsonFile.length - 1; i >= 0; i--) {
c1 = jsonFile[i].id.length
c2 = jsonFile[i].name.length
c3 = jsonFile[i].email.length
console.log("|| %s %s|| %s %s|| %s %s||", jsonFile[i].id, " ".repeat(l1-c1), jsonFile[i].name, " ".repeat(l2-c2), jsonFile[i].email, " ".repeat(l3-c3))
}
console.log("%s", "_".repeat(l1+l2+l3+14))
main();
}
function main(){
console.log("Enter a command: - add list nice get remove update search load save end")
prompt.get(['command'], function(err, result){
if (result.command == "list") {
promptMenuCommand();
}else if (result.command == "add"){
promptAddItem();
}else if (result.command == "get"){
promptGetCommand();
}else if (result.command == "remove"){
promptRemoveCommand();
}else if (result.command == "update"){
promptUpdateCommand();
}else if (result.command == "search"){
promptSearchCommand();
}else if (result.command == "load"){
promptLoadCommand();
}else if (result.command == "nice"){
promptNiceCommand();
}else if (result.command == "save"){
promptSaveCommand();
}else{
console.log("Thank you for using our program!");
console.log("Have a nice day!");
return;
};
})o
}
main();
That’s all folks! The code in GitHub is here. Finally:
Probably the answer is “NO”, but I like the picture.