So i am working with firebase in nodejs, there is a "number" attribute in each of my document of a specific table(name generated at runtime). I want to get the data having the attribute "number"'s maximum value.
Here is my sample data:-
-L1GIb7Vyn6Yhd5gghH0
correct: blah
number: 9
question: A sample question
wrong1: blekh
wrong2: blahhh
I have seen answers like "childAdded" and all but all in vain also I can't use .endAt() or startAt() because I don't know the "number"'s value at any time.
My sample code till now is:-
queRef.child(req.session.quiztopicname+req.session.quiztopictype).
orderByChild("number").endAt(9).once("value",function(snapshot){
console.log(snapshot.val());
});
Use limitToLast(1) on your sorted reference/query to only retrieve the greatest value. Bear in mind that if there are multiple children with the same greatest value, you'll still only get one of them. There's more documentation or sorting and filtering here.
Related
It seems to be a simple question but I have a hard time to find an answer to it. I already have a project with several parameters (project and database parameters). I would like to obtain the LCA results for several scenarios with my parameters having different values each time. I was thinking of the following simple procedure:
change the parameters' value,
update the exchanges in my project,
calculate the LCA results.
I know that the answer should be in the documentation somewhere, but I have a hard time to understand how I should apply it to my ProjectParameters, DatabaseParameters and ActivityParameters.
Thanks in advance!
EDIT: Thanks to #Nabla, I was able to come up with this:
For ProjectParameter
for pjparam in ProjectParameter.select():
if pjparam.name=='my_param_name':
break
pjparam.amount = 3
pjparam.save()
bw.parameters.recalculate()
For DatabaseParameter
for dbparam in DatabaseParameter.select():
if dbparam.name=='my_param_name':
break
dbparam.amount = 3
dbparam.save()
bw.parameters.recalculate()
For ActivityParameter
for param in ActivityParameter.select():
if param.name=='my_param_name':
break
param.amount = 3
param.save()
param.recalculate_exchanges(param.group)
You could import DatabaseParameter and ActivityParameter iterate until you find the parameter you want to change, update the value, save it and recalculate the exchanges. I think you need to do it in tiers. First you update the project parameters (if any) then the database parameters that may depend on project parameters and then the activity parameters that depend on them.
A simplified case without project parameters:
from bw2data.parameters import ActivityParameter,DatabaseParameter
# find the database parameter to be updated
for dbparam in DatabaseParameter.select():
if (dbparam.database == uncertain_db.name) and (dbparam.name=='foo'):
break
dbparam.amount = 3
dbparam.save()
#there is also this method if foruma depend on something else
#dbparam.recalculate(uncertain_db.name)
# here updating the exchanges of a particular activity (act)
for param in ActivityParameter.select():
if param.group == ":".join(act.key):
param.recalculate_exchanges(param.group)
you may want to update all the activities in the project instead of a single one like in the example. you just need to change the condition when looping through the activity parameters.
I have a type ORM query that returns five columns. I just want the company column returned but I need to select all five columns to generate the correct response.
Is there a way to wrap my query in another select statement or transform the results to just get the company column I want?
See my code below:
This is what the query returns currently:
https://i.stack.imgur.com/MghEJ.png
I want it to return:
https://i.stack.imgur.com/qkXJK.png
const qb = createQueryBuilder(Entity, 'stats_table');
qb.select('stats_table.company', 'company');
qb.addSelect('stats_table.title', 'title');
qb.addSelect('city_code');
qb.addSelect('country_code');
qb.addSelect('SUM(count)', 'sum');
qb.where('city_code IS NOT NULL OR country_code IS NOT NULL');
qb.addGroupBy('company');
qb.addGroupBy('stats_table.title');
qb.addGroupBy('country_code');
qb.addGroupBy('city_code');
qb.addOrderBy('sum', 'DESC');
qb.addOrderBy('company');
qb.addOrderBy('title');
qb.limit(3);
qb.cache(true);
return qb.getRawMany();
};```
[1]: https://i.stack.imgur.com/MghEJ.png
[2]: https://i.stack.imgur.com/qkXJK.png
TypeORM didn't meet my criteria, so I'm not experienced with it, but as long as it doesn't cause problems with TypeORM, I see an easy SQL solution and an almost as easy TypeScript solution.
The SQL solution is to simply not select the undesired columns. SQL will allow you to use fields you did not select in WHERE, GROUP BY, and/or ORDER BY clauses, though obviously you'll need to use 'SUM(count)' instead of 'sum' for the order. I have encountered some ORMs that are not happy with this though.
The TS solution is to map the return from qb.getRawMany() so that you only have the field you're interested in. Assuming getRawMany() is returning an array of objects, that would look something like this:
getRawMany().map(companyRecord => {return {company: companyRecord.company}});
That may not be exactly correct, I've taken the day off precisely because I'm sick and my brain is fuzzy enough I was making too many stupid mistakes, but the concept should work even if the code itself doesn't.
EDIT: Also note that map returns a new array, it does not modify the existing array, so you would use this in place of the getRawMany() when assigning, not after the assignment.
I've been trying to make a ship command that can either ship the author of the message with a mentioned user, or ship two mentioned users. I can get the 1st mention in a message but I have no idea on how to get the 2nd or even third mention in a message. I tried using:
message.mentions.users.first(2)
splitting the args then slicing them so only the second mention is avalaible, but this gives an "undefined" error when I try to get the username.
Could someone give me a script on exactly how to do it since I can't really get the hang of this
According to the documentation message.mentions.users yields a Collection. So you can just iterate over this collection or convert it to an array and then access the required index:
const userArray = message.mentions.users.array();
console.log(userArray[yourDesiredIndex]);
The official example from telegram explains that in order to use getChats() command, one needs to set two parameters 'offset_order' and 'offset_chat_id'.
I'm using this node.js wrapper for the TDLib.
So when I use getChats() with the following params:
'offset_order': '9223372036854775807',
'offset_chat_id': 0,
'limit': 100
just like it is explained in the official docs:
For example, to get a list of chats from the beginning, the
offset_order should be equal to 2^63 - 1
as a result I get 100 chats from the top of the user's list.
What I can't understand is how do I iterate through that list? How do I use the API pagination?
When I try to enter a legitimate chat_id from the middle of the first 100, I still get the same first 100, so it seems like it makes no difference.
If I change that offset_order to ANY other number, I get an empty list of chats in return...
Completely lost here, as every single example I found says the same thing as the official docs, ie how to get the first 100.
Had the same problem, have tried different approaches and re-read documentation for a long time, and here is a decision:
do getChats as you do with '9223372036854775807' offset_order parameter
do getChat request with id of the last chat you have got. It's an offline request, just to tdlib.
here you get a chat object with positions property - get a position from here, looks like this:
positions: [
{
_: 'chatPosition',
list: [Object],
order: '6910658003385450706',
is_pinned: false
}
],
next request - getChats - use the positions[0].order from (3) as offset_order
goto (2) if there are more chats
It wasn't easy to come to this, so would be glad if it helps anybody who came from google like me :)
I have a view wich returns several elements with array keys.
Example :
{"total_rows":4,"offset":0,"rows":[
{"id":"","key":[15,"2"],"value":1,"doc":{},
{"id":"","key":[20,"2"],"value":1,"doc":{},
{"id":"","key":[20,"3"],"value":1,"doc":{},
{"id":"","key":[20,"4"],"value":1,"doc":{}
]}
I'm trying to search through those elements. So if I do the following request :
/database/_design/element/_view/all/?
startkey=[15, "2"]&
endkey=[20, "3"]&
include_docs=true&reduce=false
Live example : http://jchris.couchone.com/keyhuh/_design/Record/_view/by_CreationDate_and_BoreholeName?startkey=[1267686720,%22sp4%22]&endkey=[1267686725,%22sp4\u9999%22]&include_docs=true&reduce=false
This one doesn't works. It returns me all the records, even the last one, which doesn't meets the second element of the array.
Strangely enough, it works with strings only.
Example :
{"total_rows":4,"offset":0,"rows":[
{"id":"","key":["15","2"],"value":1,"doc":{},
{"id":"","key":["20","2"],"value":1,"doc":{},
{"id":"","key":["20","3"],"value":1,"doc":{},
{"id":"","key":["20","4"],"value":1,"doc":{}
]}
if I do the following request :
/database/_design/element/_view/all/?
startkey=["15", "2"]&
endkey=["20", "3"]&
include_docs=true&
reduce=false
Live Example : http://jchris.couchone.com/keyhuh/_design/Record/_view/by_Client_and_BoreholeName?startkey=[%22Test1%22,%22sp4%22]&endkey=[%22Test1%22,%22sp4\u9999%22]&include_docs=true&reduce=false
Here it'll work well and only return the three first elements.
Am I missing something with couchdb's search for arrays with integers and strings ? Or have I fallen on a bug ?
Note : it does the same with CouchDB 0.10 and 0.11.
This looks wrong, and there are a few things it could be. Is it possible for you to share your code with us? If the data isn't proprietary you could replicate your db to http://jchris.couchone.com/keyhuh and I'll take a look at the whole thing there.
...
Thanks for posting the live data. This is the query that is busted?
http://jchris.couchone.com/keyhuh/_design/Record/_view/by_Client_and_BoreholeName?startkey=[%22Test1%22,%22sp4%22]&endkey=[%22Test1%22,%22sp4\u9999%22]&reduce=false
Because that looks fine to me. What am I missing?