I've been digging around a little trying to figure out how I should locate the "tweet_id" in my #savedtweets table and then locate that same "tweet_id" in my #newtweets table from a controller, so far I'ved tried something like this;
CONTROLLER
#stweet = Savedtweet.find(params[:id])
#newtweet = Newtweet.where(:tweet_id => #stweet.tweet_id)
#newtweet.status = 'new'
#newtweet.save
Basically I need to change the string "saved" in my Newtweets table to "new" based on the current Savedtweet ID. I just can't figure it out. If I do the following in console;
#stweet = Savedtweet.first
#newtweet = Newtweet.where(:tweet_id => #stweet.tweet_id)
It finds the right one. I've got to be close just not there yet. :)
You could do:
Newtweet.find_by_tweet_id(#stweet.tweet_id).update_attribute(:status, 'new')
The reason your code isn't working is because Newtweet.where() returns an array of objects. It should be Newtweet.where().first, though Newtweet.find_by_tweet_id is the preferred method.
Related
I have a table KmRelationship which associates Keywords and Movies
In keyword index I would like to list all keywords that appear most frequently in the KmRelationships table and only take(20)
.order doesn't seem to work no matter how I use it and where I put it and same for sort_by
It sounds relatively straight forward but i just can't seem to get it to work
Any ideas?
Assuming your KmRelationship table has keyword_id:
top_keywords = KmRelationship.select('keyword_id, count(keyword_id) as frequency').
order('frequency desc').
group('keyword_id').
take(20)
This may not look right in your console output, but that's because rails doesn't build out an object attribute for the calculated frequency column.
You can see the results like this:
top_keywords.each {|k| puts "#{k.keyword_id} : #{k.freqency}" }
To put this to good use, you can then map out your actual Keyword objects:
class Keyword < ActiveRecord::Base
# other stuff
def self.most_popular
KmRelationship.
select('keyword_id, count(keyword_id) as frequency').
order('frequency desc').
group('keyword_id').
take(20).
map(&:keyword)
end
end
And call with:
Keyword.most_popular
#posts = Post.select([:id, :title]).order("created_at desc").limit(6)
I have this listed in my controller index method which allows the the order to show the last post with a limit of 6. It might be something similar to what you are trying to do. This code actually reflects a most recent post on my home page.
In my current project, I have to get some data in a column of one table and put them to the 2nd table. The first table data have been saved as hash as follows:
---
- werweqr
- test
- B1
- B2
- B3
- xvxczv
I write the following code in the migration file to add the data from the first table to the 2nd table. But the data are not sending from the first to second.
#scenario_response = ScenarioResponse.where("selected_barriers != ?", "");
#scenario_response.each do |p|
p.selected_barriers.each do |barrier|
Settings.test = barrier
# SelectedBarriers.create(:scenario_response_id => p.id, :barrier => barrier)
end
end
Can anyone please let me know if there's something wrong in my code.
If so how to fix it?
Thanks a lot
I don't think you need to call "each" on p.selected_barriers.Try removing the each and doing this:
Settings.test=p.selected_barriers.
I'm new to RoR too..According to me,the scenario_response is a collection that returns all instances that have the selected_barriers as "". Since you are doing an each on the collection, you will just have one selected_barriers item for each of them.
Please try this and let me know if I'm wrong.
Also you are not doing update_attributes.
Try doing Settings.update_attributes(params[:test]) after Settings.test = barrier .
How do you work with the old values of a record being updated?
For instance in the following code block how would I run a query using the previous winner_id field after I determine that it has indeed changed?
if self.winner_id_changed?
old_value = self.changed_attributes
User.find(old_value)
#do stuff with the old winner....
end
An example output of self.changed_attributes would be:
{"winner_id"=>6}
Do I really have to convert this to a string and parse out the value in order to perform a query on it? old_value[:winner_id] doesn't seem to do anything.
Use where instead of find, and the following inject method on changes to generate the desired hash:
if self.winner_id_changed?
old_value = self.changes.inject({}) { |h, (k,v)| h[k] = v.first }
old_user = User.where(old_value)
#do stuff with the old user....
end
You can also use ActiveRecord dirty methods such as:
self.winner_id_was
to get specific attribute's old value. Full documentation may be found here.
In rails 3, I would like to do the following:
SomeModel.where(:some_connection_id => anArrayOfIds).select("some_other_connection_id")
This works, but i get the following from the DB:
[{"some_other_connection_id":254},{"some_other_connection_id":315}]
Now, those id-s are the ones I need, but I am uncapable of making a query that only gives me the ids. I do not want to have to itterate over the resulst, only to get those numbers out. Are there any way for me to do this with something like :
SomeModel.where(:some_connection_id => anArrayOfIds).select("some_other_connection_id").values()
Or something of that nautre?
I have been trying with the ".select_values()" found at Git-hub, but it only returns "some_other_connection_id".
I am not an expert in rails, so this info might be helpful also:
The "SomeModel" is a connecting table, for a many-to-many relation in one of my other models. So, accually what I am trying to do is to, from the array of IDs, get all the entries from the other side of the connection. Basicly I have the source ids, and i want to get the data from the models with all the target ids. If there is a magic way of getting these without me having to do all the sql myself (with some help from active record) it would be really nice!
Thanks :)
Try pluck method
SomeModel.where(:some => condition).pluck("some_field")
it works like
SomeModel.where(:some => condition).select("some_field").map(&:some_field)
SomeModel.where(:some_connection_id => anArrayOfIds).select("some_other_connection_id").map &:some_other_connection_id
This is essentially a shorthand for:
results = SomeModel.where(:some_connection_id => anArrayOfIds).select("some_other_connection_id")
results.map {|row| row.some_other_connection_id}
Look at Array#map for details on map method.
Beware that there is no lazy loading here, as it iterates over the results, but it shouldn't be a problem, unless you want to add more constructs to you query or retrieve some associated objects(which should not be the case as you haven't got the ids for loading the associated objects).
I use jqGrid to display data which is retrieved using NHibernate. jqGrid does paging for me, I just tell NHibernate to get "count" rows starting from "n".
Also, I would like to highlight specific record. For example, in list of employees I'd like a specific employee (id) to be shown and pre-selected in table.
The problem is that this employee may be on non-current page. E.g. I display 20 rows from 0, but "highlighted" employee is #25 and is on second page.
It is possible to pass initial page to jqGrid, so, if I somehow use NHibernate to find what page the "highlighted" employee is on, it will just navigate to that page and then I'll use .setSelection(id) method of jqGrid.
So, the problem is narrowed down to this one: given specific search query like the one below, how do I tell NHibernate to calculate the page where the "highlighted" employee is?
A sample query (simplified):
var query = Session.CreateCriteria<T>();
foreach (var sr in request.SearchFields)
query = query.Add(Expression.Like(sr.Key, "%" + sr.Value + "%"));
query.SetFirstResult((request.Page - 1) * request.Rows)
query.SetMaxResults(request.Rows)
Here, I need to alter (calculate) request.Page so that it points to the page where request.SelectedId is.
Also, one interesting thing is, if sort order is not defined, will I get the same results when I run the search query twice? I'd say that SQL Server may optimize query because order is not defined... in which case I'll only get predictable result if I pull ALL query data once, and then will programmatically in C# slice the specified portion of query results - so that no second query occur. But it will be much slower, of course.
Or, is there another way?
Pretty sure you'd have to figure out the page with another query. This would surely require you to define the column to order by. You'll need to get the order by and restriction working together to count the rows before that particular id. Once you have the number of rows before your id, you can figure what page you need to select and perform the usual paging query.
OK, so currently I do this:
var iquery = GetPagedCriteria<T>(request, true)
.SetProjection(Projections.Property("Id"));
var ids = iquery.List<Guid>();
var index = ids.IndexOf(new Guid(request.SelectedId));
if (index >= 0)
request.Page = index / request.Rows + 1;
and in jqGrid setup options
url: "${Url.Href<MyController>(c => c.JsonIndex(null))}?_SelectedId=${Id}",
// remove _SelectedId from url once loaded because we only need to find its page once
gridComplete: function() {
$("#grid").setGridParam({url: "${Url.Href<MyController>(c => c.JsonIndex(null))}"});
},
loadComplete: function() {
$("#grid").setSelection("${Id}");
}
That is, in request I lookup for index of id and set page if found (jqGrid even understands to display the appropriate page number in the pager because I return the page number to in in json data). In grid setup, I setup url to include the lookup id first, but after grid is loaded I remove it from url so that prev/next buttons work. However I always try to highlight the selected id in the grid.
And of course I always use sorting or the method won't work.
One problem still exists is that I pull all ids from db which is a bit of performance hit. If someone can tell how to find index of the id in the filtered/sorted query I'd accept the answer (since that's the real problem); if no then I'll accept my own answer ;-)
UPDATE: hm, if I sort by id initially I'll be able to use the technique like "SELECT COUNT(*) ... WHERE id < selectedid". This will eliminate the "pull ids" problem... but I'd like to sort by name initially, anyway.
UPDATE: after implemented, I've found a neat side-effect of this technique... when sorting, the active/selected item is preserved ;-) This works if _SelectedId is reset only when page is changed, not when grid is loaded.
UPDATE: here's sources that include the above technique: http://sprokhorenko.blogspot.com/2010/01/jqgrid-mvc-new-version-sources.html