What parameter needs to pass for the MongoEngine update_one() to get the updated document in return? Currently, it is returning 0 or 1.
Instead of using update_one() I used the method modify(). Pass the parameter new = True to it to get the updated result
According to the mongoengine documentation there doesn't seem to be anything you can pass to update_one to return the updated document. I've tried this myself in a test environment and I'm also getting either a 0 or 1 returned.
There is a parameter you can pass to update called full_result which gives you a bit more information but it's nothing that would help you in this case.
Related
I made a function which needs 2 mentions, so I first check the size with:
if (message.mentions.members.size == 2)
It works, but then I need to get both mentions. The following works, but it only gets me the first one:
message.mentions.members.first()
I've also tried other ways to get both mentions, like this one below, that returns undefined.
message.mentions.members[0]
first() takes an optional count parameter if you see here.
You can use this to return an array of the members, like so:
message.members.first(2);
The reason mentions.members[0] doesn't work is because members is a Collection (a discord.js enhancement of a map) which uses a snowflake as a key, 0 is not a valid snowflake and thus returns undefined.
How can I check whether there is a specific parameter inside req.param() in sails.js?
For example, I want to check whether the parameter X_id exists in req.param(). If the parameter exists, then I want to use it. If it doesn't exist, then I want to use a default value instead. I've tried the following code:
X_owner: req.param('X_id') || -1,
But I receive an error when I run this code with out X_id parameter. How can I fix the code?
If you're aiming to use default values for your parameters, I'd suggest using actions2 if you haven't tried. It lets you define parameters (using the inputs' object) and use defaultsTo on inputs you want to have default values for, just like in your models attribute definitions. Using these should help resolve the issue.
As for how to check whether there is a specific parameter inside req.param(), you can use req.allParams() to reveal all current parameters from all sources. These include parameters parsed from the url path, the request body, and the query string in that order.
On Django we can use the QuerySet.exists() to check if an object exists in the DB in the most efficient way, without actually fetching the record.
Is there an equivalent function on Mongoengine?
According to official documentation, here is solution how to make this if you have object id.Its the best solution for your case, that i have seen in mongoengine documentation.It works as below:
# Returns None or Object if it exists
result = Collection.objects.with_id(object_id=*your object id*)
if result is None:
# raise error
else:
# make some actions with this object
Is this is what are you looking for?
When I db.collection('example').update({"a":1},{"$set":{"b":2}},{multi:true},function(e,r){
I get r:
{
n:3,
nModified:3,
ok:1
}
This works, I can see If I look at my db that I have successfully updated 3 documents but where are my results?
Quoted from https://mongodb.github.io/node-mongodb-native/markdown-docs/insert.html
callback is the callback to be run after the records are updated. Has three parameters, the first is an error object (if error occured), the second is the count of records that were modified, the third is an object with the status of the operation.
I've tried with 3 outputs in the callback but, then I just get null as a result
db.collection('example').update({"a":1},{"$set":{"b":2}},{multi:true},function(e,n,r){
My documents have been successfully updated but r is null!
I am expecting for this to return my updated documents
It doesn't look like this operation ever does, so how can I manullay return the documents that got changed?
You can use findAndModify to get the updated document in the result. It's callback has 2 parameters:
1- error
2- Updated document
I am not sure this would work for you, but check [documentation]: https://mongodb.github.io/node-mongodb-native/markdown-docs/insert.html#find-and-modify for more info.
To get the updated documents in the returned result, you'll need to use the db.collection.bulkWrite method instead.
I want to create a "prepared statement" in postgres using the node-postgres module. I want to create it without binding it to parameters because the binding will take place in a loop.
In the documentation i read :
query(object config, optional function callback) : Query
If _text_ and _name_ are provided within the config, the query will result in the creation of a prepared statement.
I tried
client.query({"name":"mystatement", "text":"select id from mytable where id=$1"});
but when I try passing only the text & name keys in the config object, I get an exception :
(translated) message is binding 0 parameters but the prepared statement expects 1
Is there something I am missing ? How do you create/prepare a statement without binding it to specific value in order to avoid re-preparing the statement in every step of a loop ?
I just found an answer on this issue by the author of node-postgres.
With node-postgres the first time you issue a named query it is
parsed, bound, and executed all at once. Every subsequent query issued
on the same connection with the same name will automatically skip the
"parse" step and only rebind and execute the already planned query.
Currently node-postgres does not support a way to create a named,
prepared query and not execute the query. This feature is supported
within libpq and the client/server protocol (used by the pure
javascript bindings), but I've not directly exposed it in the API. I
thought it would add complexity to the API without any real benefit.
Since named statements are bound to the client in which they are
created, if the client is disconnected and reconnected or a different
client is returned from the client pool, the named statement will no
longer work (it requires a re-parsing).
You can use pg-prepared for that:
var prep = require('pg-prepared')
// First prepare statement without binding parameters
var item = prep('select id from mytable where id=${id}')
// Then execute the query and bind parameters in loop
for (i in [1,2,3]) {
client.query(item({id: i}), function(err, result) {...})
}
Update: Reading your question again, here's what I believe you need to do. You need to pass a "value" array as well.
Just to clarify; where you would normally "prepare" your query, just prepare the object you pass to it, without the value array. Then where you would normally "execute" your query, set the value array in the object and pass it to the query. If it's the first time, the driver will do the actual prepare for you the first time around, and simple do binding and execution for the rest of the iteration.