I'm trying to figure out if it's possible to simply open up a JSON data script with nodejs and edit it... as javascript ...
// my json data
{
people : [{
name : 'Joe',
hobby : 'hunting',
job : 'accountant'
},{
name : 'William',
hobby : 'chess',
job : 'manager'
}]
}
i just want to do something like e.g.
people[0].name = 'Joseph'
so i'm trying
fs.open('/path/to/file', 'r+', function(err, fd){
// not really sure what to do from here...
})
there are plenty of answers about how to read/write text files... i just thought there might be an easier way for the case of a file in JSON
Whoops this is a repeat question - please see an earlier response here
How to update a value in a json file and save it through node.js
Parse the JSON using JSON.parse(), modify the parsed object, turn it back into a new string using JSON.stringify(), then save the string to the file.
Related
I have a record that looks like this
name, value
Parent Name
MyName, MyValue
Parent Name
OtherName, OtherValue
This should translate into
[
{
name:"ParentName",
children: [
{
name: "myName",
value: "myValue"
},{
name: "otherName",
value: "otherValue"
}
]
}
]
Now I know this is poorly put together CSV but I can't control that so I need to use it as it currently is done. I could preprocess it but I am not sure how I would tell if it is the parent line or a child line.
Is there a good way to parse these sorts of documents using Node?
This is not a CSV format by any definition of such format. As such, you're not going to find any ready-made CSV code to parse this or to put it into your desired output.
Instead, you're going to have to write your own code to read it, parse it and organize it the way you want the output.
I'm using Mongoose in Node.js, and I am wondering if it is possible to refer to the currently selected document using "this" or a similar mechanism. Here is the use case I'm looking for :
Mongoose Schema :
const mySchema = mongoose.Schema({
position: Number,
date: Number,
lastEventDate: Number
});
Let's say that, at some point in time, an event occurs.
For a document selected through its position, I want to update "lastEventDate" to the document's date.
Here is my dream code :
myModel.findOneAndUpdate(
{position: myPosition},
{$set: {
'lastEventDate': THISDOCUMENT.date
}}
);
Note : I'm using $set here because the actual code updates subdocuments...
Is there a built-in "THISDOCUMENT" reference such as the one I'm dreaming of, to do it all in a single query ?
Or do I have to first query the value before updating the document (two queries).
Couldn't find anything on the web, and I'm quite the newbie when it comes to using "this".
Thanks for any kind of help !
[EDIT :] Precisions about the objective :
I am in a situation where I only have the position "myPosition" to identify the correct document, and I want to set "lastEventDate" to the same value as "date" for that document.
My question is about efficiency : is it possible to perform the update in a single upload query ? Or do I have to first download the "date" value before uploading it back to the "lastEventDate" key ?
Gathering all the information provided, I will venture on a possible answer!
You could try something like:
Your schema JS file
const mySchema = mongoose.Schema({
position: Number,
date: Number,
lastEventDate: Number
});
mySchema.methods.doYourThing(){
this.lastEventDate=this.date; //it will set the lastEventDate
}
mongoose.model("myModel", MySchema, "mycollection")
Now, whenever you call doYourThing(), the action wanted will take place, you call it after you have a instance of the mode.
This is from my own code
const token = user.generateJwt(expirationDate); //send a token, it will be stored locally in the browser
it is inside a function that return an instance of user, and in the model User I have done a function called generateJwt like I have showed, and we have something like this:
return jwt.sign(
{
_id: this._id, //this is created automatically by Mongo
email: this.email,
name: this.name,
exp: parseInt(expiry.getTime() / 1000, 10), //Includes exp as UNIX time in seconds
level: this.level,
lastLogin: this.lastLogin,
failedLogin: this.failedLogin
},
process.env.JWT_SECRET
); // DO NOT KEEP YOUR SECRET IN THE CODE!
It returns all the information of the user!
Please, do not hesitate to add comments and feebacks, I am not sure it is what you want, but that is why I have understood your request.
Anothe option is using Virtuals, they also have access to this.
So I have an object using a dictionary to store products that a user has added to the cart in a shopping cart application. I am taking is object and attempting to insert into mongoDB with zero luck.
The piece of data I am attempting to insert looks like this:
products: '{"rJUg4uiGl":{"productPrice":"78.34","count":2},"BJ_7VOiGg":{"productPrice":"3","count":2}}' }
My process of attempting to insert it into mongoDB looks like this:
db.orders.insert("products":{"rJUg4uiGl":{"productPrice":"78.34","count":2},"BJ_7VOiGg":{"productPrice":"3","count":2}});
Currently with this approach I get the following error:
2016-12-15T18:11:43.862-0500 E QUERY [thread1] SyntaxError: missing ) after argument list #(shell):1:27
Which is implying there is some sort of a formatting issue with inserting it. I have moved quotation marks and parenthesis around plenty, simply to either get the above error, or a ... response from mongoDB implying that it is waiting for me to do something more to fix what exactly is causing an error.
Any chance anyone could help give some guidance in the best way to store this object in mongoDB?
My true question feels that it should have been in regards to the mongoose schema that would be used in order to store this data format. I hoped that getting how to initially insert it into mongodb was going to be enough but the way the data is being saved has me a bit confused. I know this is a bit of an awful question but could I get any assistance with setting up my schema for this as well?
"products" : {
"rJUg4uiGl" : {
"productPrice" : "78.34",
"count" : 2
},
"BJ_7VOiGg" : {
"productPrice" : "3",
"count" : 2
}
}
This is what the data looks like when it is stored in mongo. I think what is confusing me on how to set up is the "rJUg4uiGl" portion of the data. I am un-sure of how exactly that is suppose to look in mongoose schema. Here are a few of my rather poor attempts:
products: {
productId: {
productPrice: Number,
count: Number
}
}
Above simply doesn't store anything in the database
products: {
productId: [{
productPrice: Number,
count: Number
}]
}
Above gives:
"products" : {
"productId" : [ ]
}
Again, I know that this is quite specific but any help at all would be extremely appreciated.
Need to wrap your insert data in {}
db.orders.insert({"products":{"rJUg4uiGl":{"productPrice":"78.34","count":2},"BJ_7VOiGg":{"productPrice":"3","count":2}}});
This is the case: A webshop in which I want to configure which items should be listed in the sjop based on a set of parameters.
I want this to be configurable, because that allows me to experiment with different parameters also change their values easily.
I have a Product collection that I want to query based on multiple parameters.
A couple of these are found here:
within product:
"delivery" : {
"maximum_delivery_days" : 30,
"average_delivery_days" : 10,
"source" : 1,
"filling_rate" : 85,
"stock" : 0
}
but also other parameters exist.
An example of such query to decide whether or not to include a product could be:
"$or" : [
{
"delivery.stock" : 1
},
{
"$or" : [
{
"$and" : [
{
"delivery.maximum_delivery_days" : {
"$lt" : 60
}
},
{
"delivery.filling_rate" : {
"$gt" : 90
}
}
]
},
{
"$and" : [
{
"delivery.maximum_delivery_days" : {
"$lt" : 40
}
},
{
"delivery.filling_rate" : {
"$gt" : 80
}
}
]
},
{
"$and" : [
{
"delivery.delivery_days" : {
"$lt" : 25
}
},
{
"delivery.filling_rate" : {
"$gt" : 70
}
}
]
}
]
}
]
Now to make this configurable, I need to be able to handle boolean logic, parameters and values.
So, I got the idea, since such query itself is JSON, to store it in Mongo and have my Java app retrieve it.
Next thing is using it in the filter (e.g. find, or whatever) and work on the corresponding selection of products.
The advantage of this approach is that I can actually analyse the data and the effectiveness of the query outside of my program.
I would store it by name in the database. E.g.
{
"name": "query1",
"query": { the thing printed above starting with "$or"... }
}
using:
db.queries.insert({
"name" : "query1",
"query": { the thing printed above starting with "$or"... }
})
Which results in:
2016-03-27T14:43:37.265+0200 E QUERY Error: field names cannot start with $ [$or]
at Error (<anonymous>)
at DBCollection._validateForStorage (src/mongo/shell/collection.js:161:19)
at DBCollection._validateForStorage (src/mongo/shell/collection.js:165:18)
at insert (src/mongo/shell/bulk_api.js:646:20)
at DBCollection.insert (src/mongo/shell/collection.js:243:18)
at (shell):1:12 at src/mongo/shell/collection.js:161
But I CAN STORE it using Robomongo, but not always. Obviously I am doing something wrong. But I have NO IDEA what it is.
If it fails, and I create a brand new collection and try again, it succeeds. Weird stuff that goes beyond what I can comprehend.
But when I try updating values in the "query", changes are not going through. Never. Not even sometimes.
I can however create a new object and discard the previous one. So, the workaround is there.
db.queries.update(
{"name": "query1"},
{"$set": {
... update goes here ...
}
}
)
doing this results in:
WriteResult({
"nMatched" : 0,
"nUpserted" : 0,
"nModified" : 0,
"writeError" : {
"code" : 52,
"errmsg" : "The dollar ($) prefixed field '$or' in 'action.$or' is not valid for storage."
}
})
seems pretty close to the other message above.
Needles to say, I am pretty clueless about what is going on here, so I hope some of the wizzards here are able to shed some light on the matter
I think the error message contains the important info you need to consider:
QUERY Error: field names cannot start with $
Since you are trying to store a query (or part of one) in a document, you'll end up with attribute names that contain mongo operator keywords (such as $or, $ne, $gt). The mongo documentation actually references this exact scenario - emphasis added
Field names cannot contain dots (i.e. .) or null characters, and they must not start with a dollar sign (i.e. $)...
I wouldn't trust 3rd party applications such as Robomongo in these instances. I suggest debugging/testing this issue directly in the mongo shell.
My suggestion would be to store an escaped version of the query in your document as to not interfere with reserved operator keywords. You can use the available JSON.stringify(my_obj); to encode your partial query into a string and then parse/decode it when you choose to retrieve it later on: JSON.parse(escaped_query_string_from_db)
Your approach of storing the query as a JSON object in MongoDB is not viable.
You could potentially store your query logic and fields in MongoDB, but you have to have an external app build the query with the proper MongoDB syntax.
MongoDB queries contain operators, and some of those have special characters in them.
There are rules for mongoDB filed names. These rules do not allow for special characters.
Look here: https://docs.mongodb.org/manual/reference/limits/#Restrictions-on-Field-Names
The probable reason you can sometimes successfully create the doc using Robomongo is because Robomongo is transforming your query into a string and properly escaping the special characters as it sends it to MongoDB.
This also explains why your attempt to update them never works. You tried to create a document, but instead created something that is a string object, so your update conditions are probably not retrieving any docs.
I see two problems with your approach.
In following query
db.queries.insert({
"name" : "query1",
"query": { the thing printed above starting with "$or"... }
})
a valid JSON expects key, value pair. here in "query" you are storing an object without a key. You have two options. either store query as text or create another key inside curly braces.
Second problem is, you are storing query values without wrapping in quotes. All string values must be wrapped in quotes.
so your final document should appear as
db.queries.insert({
"name" : "query1",
"query": 'the thing printed above starting with "$or"... '
})
Now try, it should work.
Obviously my attempt to store a query in mongo the way I did was foolish as became clear from the answers from both #bigdatakid and #lix. So what I finally did was this: I altered the naming of the fields to comply to the mongo requirements.
E.g. instead of $or I used _$or etc. and instead of using a . inside the name I used a #. Both of which I am replacing in my Java code.
This way I can still easily try and test the queries outside of my program. In my Java program I just change the names and use the query. Using just 2 lines of code. It simply works now. Thanks guys for the suggestions you made.
String documentAsString = query.toJson().replaceAll("_\\$", "\\$").replaceAll("#", ".");
Object q = JSON.parse(documentAsString);
I want to update one column of all rows collection by creating a concatnated string
My Schema has a property fileName and I would like construct a new property url.
Can I refernce the current row/record to build a query which would look something like this?
dbSchema.File.update({}, { $set: { url: '/view/images/'+ fileName}}, options, callback);
Obviously the above does not work because fileName is not in scope..
Whats the best way of achieving this?
You'll need to do this manually and update each document in JavaScript and resave the document.
db.file.find().forEach(function(doc) {
// make your needed updates
db.file.update({_id:doc._id}, { $set : { url: 'newPath/' + filename }});
});
While you could do it from Mongoose, there's not much reason to if you have access to the console.
Otherwise, you'll need to do the exchange on the fly as you encounter unchanged documents, by looking for an indicator that the data hasn't been fixed.