By default all related model lists for the main Crud table instance will be fetched, but only for add , edit and corresponding admin actions. Should you need more fine grain control over the lists fetched, you can configure it statically or use dynamic methods.
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For index methods, you can specify the related models which should be contained during the pagination query. You can enable and disable which model relations you want to have automatically fetched very easily, as shown below. The above example will add a contain to your query for all related models in your index method, and will perform a find 'list' for related data for your add and edit actions.
Cache this value somewhere and use it for estimation. The following query illustrates the usage with a more complete example:. Additionally, you get the number rounded more user friendly and you'll get a column called "more", which indicates if there are further elements to show a "and more" or something like this.
Okay, we get to the more important part of this article, the retrieval of the page elements.lingcaloka.tk
As indicated above, large offsets slow down the entire system, thus we have to rewrite the queries in order to make usage of an index. As an illustration I create a new table "news", where we sort by topicality and realize an efficient pagination on it. For simplicity, we suppose the newest elements also have the highest ID:. A very fast approach is using a query which is based on the last ID the user has seen. The query for the next page looks like this, where you have to pass the id of the last element on a page:. The query for the previous page looks similar, where you have to pass the id of the first element on a page and sort in reverse order sure, you havee to sort the resulting rows again :.
The problem with this approach is, it's good for a "older articles" link in the footer of a blog or when you reduce your pagination to "next" and "previous" buttons. If you want to generate a real pagination navigation, things get tricky. An idea would be getting more elements and pick out the Id's like this:. This way you get an offset id for every button you want to show in the user interface.
A small note for my jQuery Paging plugin, I've mentioned earlier; every "block" element has an own ID, which is more or less the position of the element in the navigation. Another big advantage over using page numbers or pre-calculated slices from the plugin is that users ever have their pagination consistent.
Imagine, you publish a new article on your site. All of your articles are shifted one position ahead on the sites. This is a problem if a user changes the site while you publish something new, because she will see one article twice. With a fixed ID offset, this problem is solved as a nice side effect. Mark Callaghan published an analogical post where he makes use of a combined index and two position variables but the same basic idea. If the records are relatively rigid, you could also just save the page number within the table and create an appropriate index on that column.
If there is a new entry added to that table once in a while, you could simply run this query to regenerate the page number cache:.
Search Sort and Pagination in ng-repeat – AngularJS
You could also add a new pagination table, which can be maintained in the background and rotated if the data is up:. With my database class, I've published another slightly different approach, which can be used for relatively small data sets, but where really no index can be used - for example in search results.
On a common server the following queries took about 2 seconds with 2M records. You could use this query in the background to generate caches or as I said on smaller data sets. On limited result sets also higher concurrence should be attainable. The approach is quite simple, I create a temporary table in which I store all the Id's - which in turn is also the slowest part of this approach.
But take a look at this where I sort the result by a dynamically generated random column:. Win-Win with the cost of one expensive copy query. But if the table isn't user specific, you could also generate such tables as cache table for all users and implement a simple table rotation. Okay, we slowly come to the end, but one last question: Isn't this is a huge effort for a simple problem? Yeah, indeed, but it could be easier, if you don't follow the standard paradigm. Just because everyone lays out such pages in the same way doesn't mean you need to.
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- Related Models — Crud v5.
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