Develop Reference

How to update mysql json column?

I am trying pass this object as parameter
{'0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE': '100000000000000000'}
In this function, to update mysql JSON column, but get Error:
ER_BAD_FIELD_ERROR: Unknown column '0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeE
eeeeeeeEEeE' in 'field list'
HOW TO pass this Object parameter correctly?
exports.update = async (jsonObj, address) => {
console.log("jsonObj", jsonObj);
const q = "UPDATE list SET balance = ? WHERE address = ?";
try {
await query(q, [jsonObj, address]);
console.log("Updated", address);
return "Ok";
} catch (err) {
throw err;
}
};

The problem is that your SQL is wrong. You will probably want to use JSON_SET('the name of your JSON column','the key of the key/value pair you want to update','the new value you want for that key/value pair).

MongoDB - Mongoose - TypeError: save is not a function

I am attempting to perform an update to a MongoDB document (using mongoose) by first using .findById to get the document, then updating the fields in that document with new values. I am still a bit new to this so I used a tutorial to figure out how to get it working, then I have been updating my code for my needs. Here is the tutorial: MEAN App Tutorial with Angular 4. The original code had a schema defined, but my requirement is for a generic MongoDB interface that will simply take whatever payload is sent to it and send it along to MongoDB. The original tutorial had something like this:
exports.updateTodo = async function(todo){
var id = todo.id
try{
//Find the old Todo Object by the Id
var oldTodo = await ToDo.findById(id);
}catch(e){
throw Error("Error occured while Finding the Todo")
}
// If no old Todo Object exists return false
if(!oldTodo){
return false;
}
console.log(oldTodo)
//Edit the Todo Object
oldTodo.title = todo.title
oldTodo.description = todo.description
oldTodo.status = todo.status
console.log(oldTodo)
try{
var savedTodo = await oldTodo.save()
return savedTodo;
}catch(e){
throw Error("And Error occured while updating the Todo");
}
}
However, since I don't want a schema and want to allow anything through, I don't want to assign static values to specific field names like, title, description, status, etc. So, I came up with this:
exports.updateData = async function(update){
var id = update.id
// Check the existence of the query parameters, If they don't exist then assign a default value
var dbName = update.dbName ? update.dbName : 'test'
var collection = update.collection ? update.collection : 'testing';
const Test = mongoose.model(dbName, TestSchema, collection);
try{
//Find the existing Test object by the Id
var existingData = await Test.findById(id);
}catch(e){
throw Error("Error occurred while finding the Test document - " + e)
}
// If no existing Test object exists return false
if(!existingData){
return false;
}
console.log("Existing document is " + existingData)
//Edit the Test object
existingData = JSON.parse(JSON.stringify(update))
//This was another way to overwrite existing field values, but
//performs a "shallow copy" so it's not desireable
//existingData = Object.assign({}, existingData, update)
//existingData.title = update.title
//existingData.description = update.description
//existingData.status = update.status
console.log("New data is " + existingData)
try{
var savedOutput = await existingData.save()
return savedOutput;
}catch(e){
throw Error("An error occurred while updating the Test document - " + e);
}
}
My original problem with this was that I had a lot of issues getting the new values to overwrite the old ones. Now that that's been solved, I am getting the error of "TypeError: existingData.save is not a function". I am thinking the data type changed or something, and now it is not being accepted. When I uncomment the static values that were in the old tutorial code, it works. This is further supported by my console logging before and after I join the objects, because the first one prints the actual data and the second one prints [object Object]. However, I can't seem to figure out what it's expecting. Any help would be greatly appreciated.
EDIT: I figured it out. Apparently Mongoose has its own data type of "Model" which gets changed if you do anything crazy to the underlying data by using things like JSON.stringify. I used Object.prototype.constructor to figure out the actual object type like so:
console.log("THIS IS BEFORE: " + existingData.constructor);
existingData = JSON.parse(JSON.stringify(update));
console.log("THIS IS AFTER: " + existingData.constructor);
And I got this:
THIS IS BEFORE: function model(doc, fields, skipId) {
model.hooks.execPreSync('createModel', doc);
if (!(this instanceof model)) {
return new model(doc, fields, skipId);
}
Model.call(this, doc, fields, skipId);
}
THIS IS AFTER: function Object() { [native code] }
Which showed me what was actually going on. I added this to fix it:
existingData = new Test(JSON.parse(JSON.stringify(update)));
On a related note, I should probably just use the native MongoDB driver at this point, but it's working, so I'll just put it on my to do list for now.

You've now found a solution but I would suggest using the MongoDB driver which would make your code look something along the lines of this and would make the origional issue disappear:
// MongoDB Settings
const MongoClient = require(`mongodb`).MongoClient;
const mongodb_uri = `mongodb+srv://${REPLACE_mongodb_username}:${REPLACE_mongodb_password}#url-here.gcp.mongodb.net/test`;
const db_name = `test`;
let db; // allows us to reuse the database connection once it is opened
// Open MongoDB Connection
const open_database_connection = async () => {
try {
client = await MongoClient.connect(mongodb_uri);
} catch (err) { throw new Error(err); }
db = client.db(db_name);
};
exports.updateData = async update => {
// open database connection if it isn't already open
try {
if (!db) await open_database_connection();
} catch (err) { throw new Error(err); }
// update document
let savedOutput;
try {
savedOutput = await db.collection(`testing`).updateOne( // .save() is being depreciated
{ // filter
_id: update.id // the '_id' might need to be 'id' depending on how you have set your collection up, usually it is '_id'
},
$set: { // I've assumed that you are overwriting the fields you are updating hence the '$set' operator
update // update here - this is assuming that the update object only contains fields that should be updated
}
// If you want to add a new document if the id isn't found add the below line
// ,{ upsert: true }
);
} catch (err) { throw new Error(`An error occurred while updating the Test document - ${err}`); }
if (savedOutput.matchedCount !== 1) return false; // if you add in '{ upsert: true }' above, then remove this line as it will create a new document
return savedOutput;
}
The collection testing would need to be created before this code but this is only a one-time thing and is very easy - if you are using MongoDB Atlas then you can use MongoDB Compass / go in your online admin to create the collection without a single line of code...
As far as I can see you should need to duplicate the update object. The above reduces the database calls from 2 to one and allows you to reuse the database connection, potentially anywhere else in the application which would help to speed things up. Also don't store your MongoDB credentials directly in the code.

How to return array of IDs with Mongoose find? [duplicate]

I have a problem where I want to be able to get all the unique cities for a collection, and my code looks something like this:
var mongoose = require("mongoose"),
Schema = mongoose.Schema;
var PersonSchema = new Schema({
name: String,
born_in_city: String
});
var Person = mongoose.model('Person', PersonSchema);
In native MongoDb I could just do db.person.distinct("born_in_city"), but there doesn't seem to be anything equivalent for Mongoose. Is the only option to iterate over all of the documents myself to do this, or is there a better solution?
In an attempt to use the underlying node-mongodb-native as suggested by the answerer I attempted to do this:
mongoose.connection.db.collections(function(err, collections){
collections[0].distinct('born_in_city', function( err, results ){
console.log( err, results );
});
});
However the results is empty and there's no error. I would also prefer to be able to fetch only the needed collection by name rather than have to filter what collections return if at all possible.

Just to give an update for Mongoose 3.x:
MyModel.find().distinct('_id', function(error, ids) {
// ids is an array of all ObjectIds
});

In my program, this code works.
Person.collection.distinct("born_in_city", function(error, results){
console.log(results);
});
by
node.js v0.4.7,
mongoose 1.3.3

I read through the source code and the node-mongodb-native driver is what powers the class. So on the connection object. So after you have done mongoose.connect(mongodb://), you can give this a shot.
if(mongoose.connections.length > 0) {
var nativeconn = mongoose.connections[0].conn;
nativeconn.person.distinct('born_in_city', function(error, results){
});
}

const findBornCity = async() => {
const bornCity = await Person.find().distinct("born_in_city")
return bornCity
}

Parse.com multiple relational queries

Here is a question for parse.com gurus.
I am using Parse Javascript API and trying to execute a query over 2 Pointers and cannot get it to work.
So i have following classes: Posts, Users, Groups. Posts has Pointer to Users. Users has a Pointer to Groups.
I need to get all POSTS, where a USER belongs to GROUP, which name starts with "Admin". Here is my code that doesn't work:
var Posts = Parse.Object.extend("Posts");
var Users = Parse.Object.extend("Users");
var Groups = Parse.Object.extend("Groups");
var query = new Parse.Query(Posts);
var innerQueryUsers = new Parse.Query(Users);
var innerQueryGroups = new Parse.Query(Groups);
innerQueryGroups.startsWith("name", "Admin");
innerQueryUsers.matchesQuery("group", innerQueryGroups);
query.matchesQuery("user", innerQueryUsers);
query.find({
success: function(data) {
},
error: function(error){
// here i get error: {code: 102, message: "bad type for $inQuery"}
}
});
Anybody have an idea how to do it right?

Edit - This can be done in one (untested) query by combining a group query and a post query with the same user query...
function postsInGroup(name) {
var groupQuery = new Parse.Query("Group");
groupQuery.equalTo("name", name);
var userQuery = new Parse.Query(Parse.User);
userQuery.matchesQuery("group", groupQuery);
var postQuery = new Parse.Query("Post");
postQuery.matchesQuery("user", userQuery);
return postQuery.find();
}
Call it like this...
postsInGroup("Admin").then(function(posts) {
console.log(JSON.stringify(posts));
}, function(error) {
console.log(JSON.stringify(error));
});
Its not clear what savings there is between this approach and first querying the group. It's likely that parse.com runs the inner queries much as you would. The difference in readability is a matter of taste.

Multiple MongoDB queries without using a loop?

I'm trying to figure out if I can make my MongoDB queries (fron Node.js) more quicker and more efficient.
Basically I have an array of "Players", each Player has a "player_id" property. I want to iterate over each Player and use the player_id to find data about the Player in a MongoDB database.
Because of the Asynchronous nature of Node.js I have to guarantee that when I send in a query to the database, the data that I get back corresponds to the player_id that was used to query.
So far I have the following code (that I simplified). What I'm most interested in is how I can achieve this without using a for loop. Thanks.
var playersArray = new Array({"player_id":1234567}, {"player_id":9847621}, {"player_id":0946783}, {"player_id":8712890});
queryDataForPlayers(playersArray, function(data){
//Done - Each Player now has a "new_data_property" property
})
function queryDataForPlayers(playersArray){
var newPlayersArray = new Array();
var counter = 0;
for(var i=0; i<playersArray.length; i++)
{
retrievePlayerData(playersArray[i].player_id, playersArray[i], function(err,data)
{
newPlayersArray.push(data);
if(++counter == playersArray.length)
{
callback(newPlayersArray);
}//end if
});
}
}
var Schema = mongoose.model('Schema');
var ObjectID = require('mongodb').ObjectID;
function retrievePlayerData(playerID, obj, callback){
Schema.find({_id:ObjectID(String(playerID))}, function(err,data){
obj["new_data_property"] = data;
callback(err,obj);
});
}

I can't really test this, but you can pass in an array of player ID's directly to mongo, and get a document set with the related data back in just one query, something like
var playersArray = new Array({"player_id":1234567}, {"player_id":9847621}, {"player_id":0946783}, {"player_id":8712890});
var Schema = mongoose.model('Schema');
var ObjectID = require('mongodb').ObjectID;
function queryDataForPlayers(playersArray, callback){
var player_ids = playersArray.map(function(player) {
return ObjectID(String(player.player_id));
});
Schema.find({
'_id': { $in: player_ids}
}, function(err, docs){
callback(err, docs);
});
}

Use $in operator... You can use it like
Schema.find({_id:{$in:[array_of_playerid]} }).exec(function(error,results)){
}