I'm trying to get variable number of records per page in Yii. The page size is dependent on the number of records that match a criteria, so It has to be changed on every AJAX request sent by Yii's pagination.
Here's a sketch of the exact problem:
Table Structure [pk, user_id, entry_date, entry_message]
The view has a CGridView with pagination enabled and pageSize set to 10. What I want to do is to show the entries from one date on one page. For example, page one should show the entries from today. Page two should show the entries from yesterday. So I presume that the limit and the offset should be variable, but I can't quiet understand how to change them.
Related
I have a web application in which I get data from my database and show in a datatable. I am facing an issue doing this as the data that I am fetching has too many rows(200 000). So when I query something like select * from table_name;
my application gets stuck.
Is there a way to handle this problem with JavaScript?
I tried pagination but I cannot figure how would i do that as datatable creates pagination for already rendered data?
Is there a way through which I can run my query through pagination at
the backend?
I have come across the same problem when working with mongodb and angularjs. I used server side paging. Since you have huge number of records, You can try using the same approach.
Assuming a case that you are displaying 25 records in one page.
Backend:
Get the total count of the records using COUNT query.
select * from table_name LIMIT 25 OFFSET
${req.query.pageNumber*25} to query limited records based on the page number;
Frontend:
Instead of using datatable, display the data in HTML table it self.
Define buttons for next page and previous page.
Define global variable in the controller/js file for pageNumber.
Increment pageNumber by 1 when next page button is clicked and
decrement that by 1 when prev button is pressed.
use result from COUNT query to put upper limit to pageNumber
variable.(if 200 records are there limit will be 200/25=8).
So basically select * from table_name LIMIT 25 OFFSET
${req.query.pageNumber*25} will limit the number of records to 25. when req.query.pageNumber=1, it will offset first 25records and sends next 25 records. similarly if req.query.pageNumber=2, it will offset first 2*25 records and sends 51-75 records.
There are two ways to handle.
First way - Handling paging in client side
Get all data from database and apply custom paging.
Second way - Handling paging in server side
Every time you want to call in database and get records according to pagesize.
You can use LIMIT and OFFSET constraints for pagination in MySQL. I understand that at a time 2 lacs data makes performance slower. But as you mention that you have to use JS for that. So make it clear that if you wants js as frontend then it is not going to help you. But as you mention that you have a web application, If that application is on Node(as server) then I can suggest you the way, which can help you a lot.
use 2 variables, named var_pageNo and var_limit. Now use the row query of mysql as
select * form <tbl_name> LIMIT var_limit OFFSET (var_pageNo * var_limit);
Do code according to this query. Replace the variable with your desire values. This will make your performance faster, and will fetch the data as per your specified limit.
hope this will helpful.
I want to use DataTables to show data to a user.
I read the document about "Server-side processing", but
I don't know PHP, so I can't figure out what has happened.
How client-side code sends the data to server-side script?
And how to let server-side script know how many records should be returned?
Please refer the Server-side processing chapter in the DataTables manual. The length parameter determines how many records are requested and start parameter determines first record index (zero-based).
Below is an excerpt from the manual:
start
Paging first record indicator. This is the start point in the current
data set (0 index based - i.e. 0 is the first record).
length
Number of records that the table can display in the current draw. It
is expected that the number of records returned will be equal to this
number, unless the server has fewer records to return. Note that this
can be -1 to indicate that all records should be returned (although
that negates any benefits of server-side processing!)
if I try to get the streaming history of a user, e.g.
http://api.deezer.com/2.0/user/.../history?access_token=...
I get the first result page but I don't see any method/parameter (like next, page, ...) to see the rest of the results.
How can I get the following result pages?
Thanks.
There are two parameters available to control the paging of data:
limit: the number of individual track objects that are returned in the request.
index: the individual track objects at the specified index that is the first result of the request to be returned.
Please, compare these two requests to get a better understanding of the paging system:
http://api.deezer.com/user/YOUR_USER_ID/history?access_token=YOUR_ACCESS_TOKEN&index=0&limit=10 will return the 10 latest tracks you listened to.
http://api.deezer.com/user/YOUR_USER_ID/history?access_token=YOUR_ACCESS_TOKEN&index=4&limit=5 will return the 5 tracks before the 5 latest tracks you listened to.
For your information, you cannot return more than 50 individual objects per page.
I have a block that displays the number of clicks on the page it is installed.
I want to display that block on every page.
I have tried creating a stack and then including that stack into a global area. The problem is that when the stack is included it includes the same block on every page.
So instead of having different blocks on every page, I have the same block on every page. That results in counting the clicks on all pages instead of only the current one.
How can I include a block on every page, but each having an unique ID as it has when added manually?
Thanks.
There's no way to have a unique block on every page without adding it manually. Even if you make it a "page type default", you'll end up with a shared block ID until you make the first edit (at which point it'll get it's own ID). And if you hardcode into the page's PHP code, it won't have a block ID at all.
With that being said, I don't know why you need a unique block ID. Obviously, each page is going to have a unique ID. So your block should be able to store clicks (I'm not sure exactly what you mean here, but it's probably irrelevant) against the page ID (collection ID in c5 parlance), and retrieve it against that, too.
Edit:
Considering your comment, and based on my understanding of what you're trying to do, there's no reason why you can't combine the block ID (which will, as you say, be duplicated across pages, but will be different on each block ON a page) and the page ID. So if you place two blocks in a stack, they'll get IDs 1 and 2. They'll have IDs 1 and 2 on every page the stack is own. So when you're trying to "record" whatever data they product, you combine the bID with the cID to get 1-103 and 2-103, and 1-4719, etc.
Edit 2:
So if your difficulty isn't so much "keying" the data, but physically storing the data, then see jordanlev's comment below. You won't be using the $btTable table as that's keyed off the bID. Instead you'll use db.xml to create a new table which can take your new key, and whatever other data you want to store. It's then your responsibility to query and update it with Loader::db(). See his block, or see the core's "survey" block for examples of how to manage your own db table.
I have build a page that displays a list of ratings in an desc order.
I want to display only 10 items at a time. how do I select only, say the 11-20 rows
from the ordered array.
Is it possible to handle this in the query itself, or do i have to fetch the whole table and screen the relevant items?
#pics = Rating.order('rating desc').limit(10)
In this specific case, use .offset(10) in your current query.
In general, search for "rails pagination" on google or here on SO.