Now let's try to edit user content. Remember, we are going to write a voting system.
Now let's write a function which will add a question.
First of all, we will take our js/files.js program and include it to index.html:
function readFile(file, callback) {
zeroFrame.cmd("fileGet", [file, false], callback);
}
function writeFile(file, content, callback) {
zeroFrame.cmd("fileWrite", [file, base64Encode(content)], callback);
}
function base64Encode(content) {
content = encodeURIComponent(content); // Split to bytes in % notation
content = unescape(content); // Join % notation as bytes (not as chars)
return btoa(content);
}
Now, let's write addQuestion() function in js/votes.js:
function addQuestion(question, answers, callback) {
...
}
If somebody wants to add a question, he has to be authorizated with ZeroID:
function addQuestion(question, answers, callback) {
authAsZeroID(function(user) {
// User rejected to authorizate
if(!user) {
callback(false);
return;
}
...
});
}
Let's open JSON file of user:
function addQuestion(question, answers, callback) {
authAsZeroID(function(user) {
// User rejected to authorizate
if(!user) {
callback(false);
return;
}
readFile("data/users/" + user.address + "/data.json", function(content) {
content = content || "";
// Parse JSON
try {
content = JSON.parse(content);
} catch(e) {
content = {
questions: [],
answers: {},
next_question_id: 0
};
}
...
});
});
}
Notice that we try to open file with user address. User address is its public key for ZeroID. If user uses KaffieID, public key and username (user property) will be different.
Now we add question, save JSON and publish user's content.json:
function addQuestion(question, answers, callback) {
authAsZeroID(function(user) {
// User rejected to authorizate
if(!user) {
callback(false);
return;
}
readFile("data/users/" + user.address + "/data.json", function(content) {
content = content || "";
// Parse JSON
try {
content = JSON.parse(content);
} catch(e) {
content = {
questions: [],
answers: {},
next_question_id: 0
};
}
var id = content.next_question_id;
content.questions.push({
id: id++,
question: question,
answers: answers.join("\n"),
date_added: Math.floor(Date.now() / 1000)
});
content = JSON.stringify(content);
writeFile("data/users/" + user.address + "/data.json", content, function() {
zeroFrame.cmd("sitePublish", {
inner_path: "data/users/" + user.address + "/content.json"
}, function() {
callback(id);
});
});
});
});
}
Notice that we don't pass privatekey to sitePublish command. That's because privatekey: null means "sign using user's private key".
We also sign data/users/{address}/content.json, but it is possible that it does not exist (eg. user added question first time). Hopefully, ZeroNet creates a content.json for us if it does not exist.
Let's check our code. Open DevTools, reload page and type the following in the console:
addQuestion("What's nofish's name?", ["nofish", "Tomas", "Jack"], console.log.bind(console));
Authorizate using ZeroID (if you are asked) and watch data/votes.db.
Try to write addAnswer() function for yourself first.
Answer:
function addQuestion(questionId, answerId, callback) {
authAsZeroID(function(user) {
// User rejected to authorizate
if(!user) {
callback(false);
return;
}
readFile("data/users/" + user.address + "/data.json", function(content) {
content = content || "";
// Parse JSON
try {
content = JSON.parse(content);
} catch(e) {
content = {
questions: [],
answers: {},
next_question_id: 0
};
}
content.answers[questionId] = answerId;
content = JSON.stringify(content);
writeFile("data/users/" + user.address + "/data.json", content, function() {
zeroFrame.cmd("sitePublish", {
inner_path: "data/users/" + user.address + "/content.json"
}, callback);
});
});
});
}
Note that we have similar functions. Let's write a library function instead:
function editUserData(handler, callback) {
authAsZeroID(function(user) {
// User rejected to authorizate
if(!user) {
callback(false);
return;
}
readFile("data/users/" + user.address + "/data.json", function(content) {
content = content || "";
// Parse JSON
try {
content = JSON.parse(content);
} catch(e) {
content = {
questions: [],
answers: {},
next_question_id: 0
};
}
handler(content);
content = JSON.stringify(content);
writeFile("data/users/" + user.address + "/data.json", content, function() {
zeroFrame.cmd("sitePublish", {
inner_path: "data/users/" + user.address + "/content.json"
}, callback);
});
});
});
}
function addQuestion(question, answers, callback) {
var id;
editUserData(function(content) {
id = content.next_question_id;
content.questions.push({
id: content.next_question_id++,
question: question,
answers: answers.join("\n"),
date_added: Math.floor(Date.now() / 1000)
});
}, function() {
callback(id);
});
}
function addAnswer(questionId, answerId, callback) {
editUserData(function(content) {
content.answers[questionId] = answerId;
}, callback);
}
Now we will write getQuestionList(), getQuestion() and getAnswers() functions:
function getQuestionList(sort, callback) {
if(sort == "popular") {
zeroFrame.cmd("dbQuery", ["SELECT questions.*, CASE WHEN answers.answer_count IS NULL THEN 0 ELSE answers.answer_count END AS answer_count FROM questions LEFT JOIN (SELECT question_id, COUNT(*) as answer_count FROM answers GROUP BY question_id) AS answers ON (answers.question_id = questions.id) ORDER BY answers.answer_count DESC, questions.date_added DESC LIMIT 0, 10"], callback);
} else if(sort == "latest") {
zeroFrame.cmd("dbQuery", ["SELECT * FROM questions ORDER BY date_added DESC LIMIT 0, 10"], callback);
}
}
function getQuestion(id, callback) {
zeroFrame.cmd("dbQuery", ["SELECT * FROM questions WHERE id = " + id], function(questions) {
zeroFrame.cmd("siteInfo", [], function(siteInfo) {
if(siteInfo.cert_user_id) { // User logged in
zeroFrame.cmd("dbQuery", ["SELECT answers.*, json.* FROM answers, json WHERE json.directory = \"users/" + siteInfo.auth_address + "\" AND answers.json_id = json.json_id AND answers.question_id = " + id], function(answer) {
if(answer.length) {
questions[0].answered = answer[0].answer_id;
getAnswers(id, function(answers) {
questions[0].answers = answers;
callback(questions[0]);
});
} else {
questions[0].answered = -1;
callback(questions[0]);
}
});
} else {
questions[0].answered = -1;
callback(questions[0]);
}
});
});
}
function getAnswers(id, callback) {
zeroFrame.cmd("dbQuery", ["SELECT answer_id, COUNT(*) as answer_count FROM answers WHERE question_id = " + id + " GROUP BY answer_id"], function(answers) {
var result = {};
for(var i = 0; i < answers.length; i++) {
result[answers[i].answer_id] = answers[i].answer_count;
}
callback(result);
});
}
Now, core is finished. Only layout is left. As usual, here is an example.