Using jqGrid free (version 4.15.6) to show very basic information about invoices (ie: date created, date due, client, total, status). The invoices grid only has a few pertinent columns that are displayed because it is just not needed to show more than that. In reality there are a lot of other invoice-related fields that are not shown. I would like to offer end-users the ability to filter the grid based on a lot of these other parameters that are simply not part of the grid contents.
I know jqGrid offers built-in searching, and you can easily just add hidden columns with all the data, but I feel this is not good for us--invoices contain a lot of data--data that is not necessarily present in just the invoices database table. We want the grid to provide many other filtering options outside of the base invoice data but we do NOT want to use the built-in filter options. Instead, I would like to use a separate HTML table with a bunch of search fields that our server-side code would know how to pull back). When one decides to invoke the external filter, we want the grid to load all invoices matching that combined filter. And if one chooses to navigate using the grid's paging buttons, we want the grid to continue using the original external filtering parameters.
Hope this makes sense. Maybe I am just overthinking this but I am fairly certain the grid is designed to use it's built in filtering/searching tools/dialog and I have not found anyway to override this behavior. Actually I have using an older jqGrid but that involved using jQuery to completely REPLACE the default pager with custom HTML and event handling. I never could figure this out with older jqGrid so I chose to write it myself. But that code is less than optimum and even I know it is subject to much criticism. Having upgraded to 4.15.6, I want to do this the best way and I want to keep it logical and practical.
I have tried using beforeRequest() and onPaging() events to change the 'url' parameter, thinking that if I modified the url, I could change the GET to include all of our custom filtering fields. It seems that does not work as the url NEVER changes from the originally defined value. Console logging does show the events firing but no change to url. On top of that, the grid ALWAYS passes its own page field, _search field, etc. to the server so the server NEVER sees the filter request.
How does one define their own custom filtering coupled with paging loader and still take advantage of the built-in paging events? What am I missing?
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It's difficult to answer on your question because you didn't posted code fragments, which shows how you use jqGrid and because the total number of data, which could be needed to display in all pages isn't known.
In general there are two main alternatives implementing of custom filtering:
One can additionally use a mix from both filtering. For example, one can load from the server all invoices based on some fixed filters (all invoices of specific user or all invoices of one organization, all invoices of the last month) and then use loadonce: true, forceClientSorting: true options to sort and to filter the returned data on the client side. The user could additionally to filter the subset of data locally using filter toolbar of searching dialog.
The performance of client side is essentially improved last years and loading relatively large JSON data from the server could be done very quickly. Because of that Client-Side-Filtering is strictly recommended. For better understanding the performance of local sorting, filtering and paging I'd recommend you to try the functionality on the demo. You will see that the timing of local filtering of the grid with 5000 rows and 13 columns is better as you can expect mostly from the round trip to the server and processing of server side filtering on some very good organized database. It's the reason why I recommend to consider to use client side sorting (or loadonce: true, forceClientSorting: true options) as far it's possible.
If you need to filter data on the server then you need just send additional parameters to the server on every request. One can do that by including additional parameters in postData. See the old answer for additional details. Alternatively one can use serializeGridData to extend/modify the data, which will be set to the server.
After the data are loaded from the server, it could be sorted and filtered locally before the first page of data will be displayed in the grid. To force local filtering one need just add forceClientSorting: true additionally to well known loadonce: true parameter. It force applying local logic on the data returned from the server. Thus one can use postData.filters, search: true to force additional local filtering and sortname and sortorder parameter to force local sorting.
One more important remark about using hidden columns. Every hidden column will force creating DOM elements, which represent unneeded <td> elements. The more DOM elements you place on the page the more slow will be the page. If local data will be used (or if loadonce: true be used) then jqGrid hold data associated with every row twice: once as JavaScript object and once as cells in the grid (<td> elements). Free jqGrid allows to use "additional properties" instead of hidden columns. In the case no data will be placed in DOM of the grid, but the data will be hold in JavaScript objects and one able to sort or filter by additional properties in the same way like with other columns. In the simplest way one can remove all hidden columns and to add additionalProperties parameter, which should be array of strings with the name of additional properties. Instead of strings elements of additionalProperties could be objects of the same structures like colModel. For example, additionalProperties: [{ name: "taskId", sorttype: "integer"}, "isFinal"]. See the demo as an example. The input data of the grid can be seen here. Another demo shows that searching dialog contains additional properties additionally to jqGrid column. The commented part columns of searching shows more advanced way to specify the list and the order of columns and additional properties displayed in searching dialog.