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The goal is to take our password manager to the next level.

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And in order to do that, we need to add a search functionality.

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It's not good enough just to look through the data file anymore.

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What we want to be able to do is the type a website into the website entry,

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and then hit search

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and we get a pop up showing us our email and the password that was saved for

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that website. So this is the goal.

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But where we're currently at is we have a text file

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which contains the name of the website, the email and the password.

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This is very difficult to search

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and this is a really terrible format to work with.

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So we're going to be leveling up our data storage in our password manager

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and we're going to switch from saving data straight to a text file to a fancier

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data format, which is called JSON. Nope,

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this is not the latest hottest DJ on the block.

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It's actually JSON,

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which stands for JavaScript Object Notation.

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This was something that was designed originally for JavaScript

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but because it has such a simple structure and it's so easy to understand and

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work with that it's been adopted by many, many different fields,

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including Python.

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This is probably one of the most popular ways of transferring data,

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especially when you're transferring data across the internet.

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So this is what we're going to be learning about.

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And for those of you looking at this slide,

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you might've already realized that it's kind of similar to the dictionaries

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that we've been working with in Python, right?

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A JSON is essentially composed of a bunch of nested lists and dictionaries,

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and it has that key value pair data structure.

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This is essentially what we're aiming for so that we can store our data in this

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format

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and we'll be able to easily load up this data and search through it for the

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particular website that we want the information for. To work with JSON data in

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Python, we can use the inbuilt JSON library,

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and we're going to use it to write, read,

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and update data to a JSON file. To begin.

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I'm going to simplify our code a little bit.

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I'm going to get rid of this message box, which asked the user OK 

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or cancel. We're just going to assume that once they click add,

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then they're happy with email and password.

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So now that we've cut down that little bit of code,

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it makes this a little bit easier to understand.

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All that we're doing here is we're checking to make sure that the length of the

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website entry and the length of the password entry is equal to zero.

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And you might still have the length checking for the email entry,

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but remember that at the end of previous lessons,

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we actually inserted a default value.

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So we can actually skip that check as well if you wanted to.

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The reason why we want our code as simple as possible is so that when we're

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working with the JSON and we're learning about how to work with it,

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as long as everything else is simple,

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then we can focus on the new things that we're learning. In this case,

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instead of opening a data.txt file,

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I'm going to change the data format to a .json.

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And instead of using the append mode,

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I'm going to use the write mode because I'm going to be writing to this data.

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json file. Now, in order to write to a JSON file,

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we don't use this line of code. Instead,

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we use a method called json.dump,

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and that, of course, requires us to import the JSON module

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which should be inbuilt to Python so you don't actually have to install it.

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Now, once we've imported our JSON module,

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we can say json.dump.

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And this takes a number of inputs, but the most important

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are the things you want to dump and the file that you want to dump it to.

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The data that we want to put in here should go in as a dictionary.

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Essentially, what we want to create is a new dictionary

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which I'll call new_data and it's going to be a nested dictionary.

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So the first level key is going to be the website,

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because this is what we're going to be searching through eventually.

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And the website is going to, itself, contain a dictionary.

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Now this dictionary contains two keys, the email,

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and also the password.

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The values for each of these are pretty self-explanatory,

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it's the email that we got from this line of code and the password is the

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password that we got from this line of code.

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Now that we've created this new dictionary called new_data,

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well that is what we're going to use to dump into our JSON file.

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Let's go ahead and dump our new data. So that's the first input. Now,

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the next input is going to be the data file that we want to put it into.

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So that is going to be the file that we opened up inside this line.

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Let's provide our data file as the location to dump this data.

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And now if I go ahead and hit run

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and I create a new entry for my Amazon website password, generate the password,

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hit add,

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then you can see that we've got our brand new data.json file

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that's just been created. So just as a quick reminder,

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when you open a file in write mode, if that file doesn't exist,

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it will actually create it. So we've created this new file, data.json,

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and we've dumped the data that we entered into that file.

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So now if I open this up,

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you can see we've got a JSON format in here and we've got our Amazon website

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and all of its associated data.

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Notice how this data is not very easy to read for a human.

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So we can actually improve that by adding one other argument.

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And it's an argument called indent. This,

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we can provide the number of spaces to indent all the JSON data so that it

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becomes much easier to read.

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So I'm going to go ahead and delete everything that's in here and I'm gonna run

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the code again. And this time,

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once I save this data into my data.json,

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you can see everything is all indented and it's much easier for the human to

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read.

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Now that we've seen how we can write data to a JSON file,

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the next step I want to show you is how you can load data from the JSON file or

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how to read from it. To read JSON data

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te use the JSON module and we call the load method.

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So I'm going to go ahead and comment out this line of code.

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And now that I've actually got some data in my data.json file,

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I'm going to try and read from it.

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We call the json.load method and we pass in the file path,

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or you can see here the fp.

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So that's the only required input.

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The file that we're going to pass in is our data file

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which we opened up over here

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ad what we're going to do is we're going to change this from write mode to read

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mode. Once we've loaded up the data,

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we're gonna save it inside a variable called data

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and then I'm just going to print it out. So when I hit run right now,

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and I simply add any sort of gobbledy goop,

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but as long as I can hit the add button,

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it's going to trigger this part of the code.

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And now if we take a look inside our console,

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you can see that data is being printed down here,

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but without any of these indentations or any of the formatting. Instead,

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what that load method does is it essentially takes this JSON data and

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converts it into a Python dictionary.

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So this data,

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if we actually do a type check on it,

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you can see it has a type of dictionary.

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This is just a normal Python dictionary.

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So essentially we can use json.dump and json. load to serialize

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and deserialize from JSON data to Python dictionaries.

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And it allows us that free interchange of information.

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We change it into a JSON to store it,

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and then we take it out of storage and turn it into a Python dictionary to

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easily work with it in our code.

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Now that we've seen how to write,

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how to read, the last thing I want to show you is how to update data.

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Because if we have a new piece of data come in,

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we want to add to this JSON but we don't want to overwrite it.

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But we also don't want to just append to the end of it,

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because as you can imagine if we had something that we just appended to the end,

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that's not a valid data structure

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and that's why we're getting all of these errors. Instead of doing it manually,

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we're going to use the builtin method json.update.

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And here's how it works. So we've already got some data inside our data.

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json file and I'm going to change this from read again, back to write.

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And what we want to do is we want to take that data and we want to update what's

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existing in there with the new data that's being passed in. To do that

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we first have to load up the data, so I'm going to uncomment this line,

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and once we've gotten hold of the data,

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we're going to say data.update.

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And we update it with the new data. What's happened so far is we have our data

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loaded up into a dictionary,

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we use the update method to update that dictionary with some new piece of data.

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Now,

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the next thing we want to do is we want to actually write that data back into

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this file.

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So we have to use this line of code using json.dump.

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But instead of dumping the new data,

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we're going to dump that data that we updated right here.

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Essentially what we're doing here is a three-step approach.

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We're reading the old data, we're updating old data with new data,

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and we're finally saving the updated data. Here

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we've got two things happening. We've got reading and we've got writing.

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So we can split this code into two sections. First,

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we open the file in read mode, we get hold of the data,

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we update the data and then we open up the file again.

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But in this case, we open it in write mode.

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This time we're going to dump the data that we've updated over here into that

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data file using this particular indent format.

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And once we written to file,

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and we delete all the text from a website and password entries and these lines

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of code now replace our previous functionality where we were saving just plain

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text to our data.txt. Let's go ahead and run it and test it out.

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Currently, we have a single entry inside our data.json.

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So if we go ahead and add a new entry,

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say for eBay, and we generate password, click add.

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If we go back to our data.json, you can see how it's now been updated.

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This entire JSON has now been updated to have two entries,

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Amazon and eBay. It didn't just append it.

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It actually added it into the dictionary

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and that's all thanks to that update method.

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And once it updated that data,

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then we told it to save the updated data back into the data file and wipe all of

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the previous data. So now that we're able to read,

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write and update JSON data,

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the next step is to think about what situations might this fail.

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And one of the biggest problems we have at the moment is we're trying to open up

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this file, load up the data and update it.

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But if we actually had no data in here,

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say the first time we ran our program, or indeed,

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if we didn't actually have this data.json file,

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then you can see that the first time I run it and I tried to save a password,

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then it's going to crush and we get some exceptions being thrown.

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But we know all about exceptions now. So in the next lesson,

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that's what we're going to tackle. For all of that,

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and more, head ever to the next lesson