For example, the. That setting defaults to case-insensitive. Contains searchString. That would ensure that results stay the same if you change the code later to use a repository which returns an IEnumerable collection instead of an IQueryable object. When you call the Contains method on an IEnumerable collection, you get the.
NET Framework implementation; when you call it on an IQueryable object, you get the database provider implementation. However, there's a performance penalty for this solution. That would prevent the optimizer from using an index.
Given that SQL is mostly installed as case-insensitive, it's best to avoid the ToUpper code until you migrate to a case-sensitive data store. Run the app, select the Students tab, enter a search string, and click Search to verify that filtering is working. If you bookmark this page, you'll get the filtered list when you use the bookmark.
At this stage, if you click a column heading sort link you'll lose the filter value that you entered in the Search box. You'll fix that in the next section. To add paging to the Students Index page, you'll create a PaginatedList class that uses Skip and Take statements to filter data on the server instead of always retrieving all rows of the table.
Then you'll make additional changes in the Index method and add paging buttons to the Index view. The following illustration shows the paging buttons.
In the project folder, create PaginatedList. The CreateAsync method in this code takes page size and page number and applies the appropriate Skip and Take statements to the IQueryable. This code adds a page number parameter, a current sort order parameter, and a current filter parameter to the method signature.
The first time the page is displayed, or if the user hasn't clicked a paging or sorting link, all the parameters will be null. If a paging link is clicked, the page variable will contain the page number to display. The ViewData element named CurrentSort provides the view with the current sort order, because this must be included in the paging links in order to keep the sort order the same while paging.
The ViewData element named CurrentFilter provides the view with the current filter string. This value must be included in the paging links in order to maintain the filter settings during paging, and it must be restored to the text box when the page is redisplayed. If the search string is changed during paging, the page has to be reset to 1, because the new filter can result in different data to display. The search string is changed when a value is entered in the text box and the Submit button is pressed.
In that case, the searchString parameter isn't null. At the end of the Index method, the PaginatedList. CreateAsync method converts the student query to a single page of students in a collection type that supports paging. That single page of students is then passed to the view. The PaginatedList. CreateAsync method takes a page number. The two question marks represent the null-coalescing operator.
Cover image by Drew Beamer on Unsplash. Toggle navigation. Home Manifesto ASP. NET Core Consulting. Sorting Requirements For sorting in our example project we'll take on the following requirements: Default sort by the first column Sort by clicking on the column header Sorting by the currently sorted column will reverse the sort order Sorting will reset paging to page 1 Sorting the data will be done at the database layer Add Order to the EF Core Query Looking at the current query we see that it is currently sorted by the widget name every time we make a call.
Filter Filter. PageSize ; To start we'll create a new "SortDirection" enum that we can use to indicate sort direction in our application. OrderBy exp : query. OrderBy "part". OrderBy Sort, Direction.
Add Sorting to Table Headers Our last step to get sorting working is to update the table headers to create the correct sort link.
Initially it looks like updating the table column to create a link should be all we need. Desc: SortDirection. Combining Columns This sorting works great but what if we had a new requirement to combine two or more values into one column? Include a using statement for it. GetFiles order by file. GetFiles orderby file. CreationTime descending, file. Name ascending select file. ToArray ;. Devraj Gadhavi Devraj Gadhavi 3, 3 3 gold badges 35 35 silver badges 64 64 bronze badges.
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