I'm trying to relate some Ids with names as the image below:
Basically I would like to create a relation between the institutes and their corresponding Ids, at my first thought was doing something like =if(A2 = 81, "Institute example 1", ""), but I would like to know if there is a better way to do it.
Depending on what you are trying to do with it you could use VLOOKUP. I have created this sample spreadsheet where you can just introduce the name of the institution and get the ID based on the name, so that would create the relation between them.
The formula I used in this sample spreadsheet is:
= VLOOKUP(G3,B4:D8,3,FALSE)
Ref:
VLOOKUP
Related
I have model named IssueFlags with columns:
id, created_at, flags_id, issue_id, comments
I want to get data of unique issue_id (latest created) with info about flags_id, created_at and comments
By sql it's working like this:
SELECT created_at, flags_id, issue_id, comments
FROM Issues_issueflags
group by issue_id
How to do the same in Django? I tried to wrote sth in shell, but there is no attribute group by
IssueFlags.objects.order_by('-created_at')
This above return me only the list of ordered data.
Try doing this way:
from django.db.models import Count
IssueFlags.objects.values('created_at', 'flags_id', 'issue_id', 'comments').order_by('-created_at').annotate(total=Count('issue_id'))
I have written annotate(total=Count('issue_id')) assuming that you would have multiple entries of unique issue_id (Note that you can do all possible types of aggregations like Sum, Count, Max, Avg inside . Also, there already exists answers for, doing group by in django. Also have a look at this link or this link. Also, read this django documentation to get a clear idea on when to place values() before annotate() and when to place it after, and then implement the learning as per your requirement.
Would be happy to help if you have any further doubts.
I am starting a project using Cloudant.
It's a simple system for logging, so I can track the usage of my apps.
My documents looks like this:
{
app:'name of the app',
type:'page view | login | etc..',
owner:'email_of_the_user',
device: 'iphone | android | etc..', date:
'yyyy-mm-dd'
}
I've tried to do some map reducing and faceted searches, but couldn't find so far the result for what I want.
I want to count the number of distinct documents grouped by same owner, date (yyyy-mm-dd), and app.
[For example, if a the same guy logs in the app twice or 20 times in the same date, it will be counted only once.
I want to count how many single users used an app each day, no matter what's the type of the log, or the device he used.]
If it was SQL, assuming that each key of the document is a column, I would query something like this:
SELECT app, date, count(*) FROM LOGS group by date, owner, app
ant the result would be something like:
'App1', '2015-06-01', 200
'App1', '2015-06-02', 232
'App2', '2015-06-01', 142
'App2', '2015-06-02', 120
How can I get the same result using Cloudant/CouchDB?
You can do this using design documents, as Cesar mentioned. A concrete example would be to create a view where your map function emits the field on where you want to group on, such as:
function(doc) {
emit(doc.email, 1);
}
Then, you select your desired reduce function (such as _count). When viewing this on Cloudant dashboard, make sure you select Reduce as part of the query options. When accessing the view via URL you need to pass the appropriate parameters (reduce=true&group=true).
The documentation on Views here is pretty thorough: https://docs.cloudant.com/creating_views.html
For what you need there is a feature on couldant/couchdb called design document. You can check their documentation for this feature for details or this guide:
http://guide.couchdb.org/draft/design.html
Cloudant documentation:
https://docs.cloudant.com/design_documents.html
Design documents are similar views on the SQL world.
Regards,
We were able to do this in our project using the Cloudant Java API...
https://github.com/cloudant/java-cloudant
You should be able to get this sort of result by creating a view that has a map function like this...
function(doc) {
emit([doc.app, doc.date, doc.owner], 1);
}
The reduce function should look like this:
function(keys, values, rereduce){
if (rereduce){
return sum(values);
} else {
return sum(values);
}
}
Then we used the following query to get the data we wanted.
Database db = ....
db.view(viewName).startKey(startKeys).endKey(endKeys)
.group(true).includeDocs(false).query(castClass)
We supplied the view name and some start and end keys (since we emitted a compound key and we needed to supply a filter) and then used the group method to get the data back as you need it.
Revised..
With this new emit key in the map function you should get results like this:
{[
{[app1, 2015,06,28, john#somewhere.net], 12}, <- john visited 12 times on that day...
{[app1, 2015,06,29, john#somewhere.net], 10},
{[app1, 2015,06,28, ann#somewhere.net], 1}
]}
If you use good start and end keys, the amount of records you're querying will stay small and the number of records you get back is the unique visitors you are seeking. Note that in this scenario you are getting back a bit more than you want, but it does work.
I have a Result object that is tagged with "one" and "two". When I try to query for objects tagged "one" and "two", I get nothing back:
q = Result.objects.filter(Q(tags__name="one") & Q(tags__name="two"))
print len(q)
# prints zero, was expecting 1
Why does it not work with Q? How can I make it work?
The way django-taggit implements tagging is essentially through a ManytoMany relationship. In such cases there is a separate table in the database that holds these relations. It is usually called a "through" or intermediate model as it connects the two models. In the case of django-taggit this is called TaggedItem. So you have the Result model which is your model and you have two models Tag and TaggedItem provided by django-taggit.
When you make a query such as Result.objects.filter(Q(tags__name="one")) it translates to looking up rows in the Result table that have a corresponding row in the TaggedItem table that has a corresponding row in the Tag table that has the name="one".
Trying to match for two tag names would translate to looking up up rows in the Result table that have a corresponding row in the TaggedItem table that has a corresponding row in the Tag table that has both name="one" AND name="two". You obviously never have that as you only have one value in a row, it's either "one" or "two".
These details are hidden away from you in the django-taggit implementation, but this is what happens whenever you have a ManytoMany relationship between objects.
To resolve this you can:
Option 1
Query tag after tag evaluating the results each time, as it is suggested in the answers from others. This might be okay for two tags, but will not be good when you need to look for objects that have 10 tags set on them. Here would be one way to do this that would result in two queries and get you the result:
# get the IDs of the Result objects tagged with "one"
query_1 = Result.objects.filter(tags__name="one").values('id')
# use this in a second query to filter the ID and look for the second tag.
results = Result.objects.filter(pk__in=query_1, tags__name="two")
You could achieve this with a single query so you only have one trip from the app to the database, which would look like this:
# create django subquery - this is not evaluated, but used to construct the final query
subquery = Result.objects.filter(pk=OuterRef('pk'), tags__name="one").values('id')
# perform a combined query using a subquery against the database
results = Result.objects.filter(Exists(subquery), tags__name="two")
This would only make one trip to the database. (Note: filtering on sub-queries requires django 3.0).
But you are still limited to two tags. If you need to check for 10 tags or more, the above is not really workable...
Option 2
Query the relationship table instead directly and aggregate the results in a way that give you the object IDs.
# django-taggit uses Content Types so we need to pick up the content type from cache
result_content_type = ContentType.objects.get_for_model(Result)
tag_names = ["one", "two"]
tagged_results = (
TaggedItem.objects.filter(tag__name__in=tag_names, content_type=result_content_type)
.values('object_id')
.annotate(occurence=Count('object_id'))
.filter(occurence=len(tag_names))
.values_list('object_id', flat=True)
)
TaggedItem is the hidden table in the django-taggit implementation that contains the relationships. The above will query that table and aggregate all the rows that refer either to the "one" or "two" tags, group the results by the ID of the objects and then pick those where the object ID had the number of tags you are looking for.
This is a single query and at the end gets you the IDs of all the objects that have been tagged with both tags. It is also the exact same query regardless if you need 2 tags or 200.
Please review this and let me know if anything needs clarification.
first of all, this three are same:
Result.objects.filter(tags__name="one", tags__name="two")
Result.objects.filter(Q(tags__name="one") & Q(tags__name="two"))
Result.objects.filter(tags__name_in=["one"]).filter(tags__name_in=["two"])
i think the name field is CharField and no record could be equal to "one" and "two" at same time.
in python code the query looks like this(always false, and why you are geting no result):
from random import choice
name = choice(["abtin", "shino"])
if name == "abtin" and name == "shino":
we use Q object for implement OR or complex queries
Into the example that works you do an end on two python objects (query sets). That gets applied to any record not necessarily to the same record that has one AND two as tag.
ps: Why do you use the in filter ?
q = Result.objects.filter(tags_name_in=["one"]).filter(tags_name_in=["two"])
add .distinct() to remove duplicates if expecting more than one unique object
I'm building web app and using django and Sphinx for free text search. I need to apply additional restrictions before making request to searchd, consider 2 tables:
Entity
id
title
description
created_by_id
updated_by_id
created_date
updated_date
and
EntityUser
id
entity_id [FK to the table above]
joining_user_id
is_approved
created_by_id
updated_by_id
created_date
updated_date
I've built RT index for main table Entity, all works fine, but then I want to make a query only on those entities to which user has joined, i.e. where for specific user_id & entity_id exists record in EntityUser with is_approved=1. Problem is that I can't index EntityUser, because there are no string fields - this table only holds integers/timestamps as you see. Not sure if I could make a query in SphinxQL containing subquery to another idex even if I could build index for that table. Knowing that Sphinx was used for quite big projects with great success, I doubt it's a limitation of Sphinx - is it bad design of DB/application or leak of knowledge how to build proper RT index? Can I somehow extend existing index so that I can use restriction above?
I was thinking that I could apply the additional restrictions after Sphinx returns IDs of records on MySQL side, but that's not going to work: N records with highest weight would be returned, but after applying additional restrictions the result could be empty. So I need to get an area of search and then perform query only on those entities user can possibly see.
Adapting the example from http://sphinxsearch.com/docs/current.html#attributes, you might be able to use something like this in your conf:
...
sql_query = SELECT app_entity.id as id,
app_entity.title as title,
app_entity.description as description,
app_entityuser.id as userid
FROM app_entity, app_entityuser
WHERE app_entity.id = app_entityuser.entity_id AND app_entityuser.is_approved = 1
sql_attr_uint = id
sql_attr_uint = userid
...
I should provide a disclaimer: I have not tried this.
I did find a related SO post, but it doesn't look like they quite solved it: Django-sphinx result filtering using attributes?
Good luck!
Actually I've found the answer and it has nothing to do with the design of application or DB.
In fact that's simple - I just need to use MVA for RT index as I would do for plain one (rt_attr_multi or rt_attr_multi_64). In configuration file I will have to do something like this:
...
rt_attr_multi = entity_users
}
and then populate it with IDs of users which have joined the Entity and have been approved. Problem was that I couldn't understand how to use MVA with RT index, but not it's clear. There are not enough real-word examples with RT indexes and MVA I think, so I've shared this to help to solve similar problems.
UPDATE: was fighting last hour to generate RT index and always was getting "unknown column: 'entity_users'". Finally found the reason - if you add MVA to RT index (don't know if that's the same for plain), you've got to not only restart searchd daemon (service), but also DELETE everything you have in "data" folder (or where you have stored your index)!
am Using Apex4.1,
in my application I have one Tabular form which has the following fields,
Emp_id
Emp_name
Dept_id
Here Emp_id is the Updatable column and it is a select list LOV and
Emp_name is a upadatable column,
Here what I need is,
If I select the Emp_id from the LOV ,the Emp_Name should be stored automatically based
on the value selected in EMP_ID,
In tabular form I could not create Dynamic action like creating in normal forms,
Can anyone help me in this issue?
Thank you.
APEX does not currently provide dynamic actions on tabular form items. Hopefully this may be addressed in APEX 4.2 but the Statement of Direction does not explicitly say so.
So for now if you need to do this you will have to write your own Javascript, using the unique IDs of the tabular form items to manipulate them (the IDs look like "fcc_rrrr" where "cc" is the column number and "rrrr" is the row number). See this SO q&q for sample Javascript code that uses these.
The Javascript you need to write is a little daunting (for a beginner), but one thing to note is that in your case you can avoid any need for using AJAX to get the employee name by embedding the name in the return value of the LOV something like this:
select emp_name d, emp_id||':'||emp_name r
from employee
order by 1
This way the return values will look like '123:John Smith'; your Javascript can parse this string and extract 'John Smith' and insert it into the emp_name item on the same row. Obviously you will also need to parse this string to obtain the emp_id value you will need when updating the database when the page is submitted.