On the first call to OnRead I check to see the last Grid state that was stored Progress is the leading provider of application development and digital experience technologies. Instead, they load data on demand via OnExpand events. Currently, you can expand any items with the ExpandedRows collection of int where you pass the indexes of the rows. The OnRead event handler receives an argument, which inherits from ReadEventArgs. The DataSourceRequest object can be serialized and sent to the remote server. Now enhanced with: The following seems to update the data correctly on my end. Progress Telerik. There are two main reasons to use the OnRead event: performance and customization. Marin Bratanov Use async Task and not async void. When the user expands a group, all its rows will be requested from the data source. First, I need a collection to hold all the data that Ive already fetched (Im calling that collection empData). This improves the performance of the database, backend, network, and the browser. Copyright 2022 Progress Software Corporation and/or its subsidiaries or affiliates. To make the Grid fire OnRead, execute its SetState method Make the grid call OnRead by using its state Edit Preview Blazor Grid Overview - Telerik UI for Blazor The expanded state of the groups is preserved during paging only, but not if sorting or filtering is applied. However, by leveraging the DataGrids OnRead event, you can retrieve data on an as you need it basis, fetching objects only as the user pages forward through the grid. If you decide that you want to be removed from our mailing lists at any time, you can change your contact preferences by clicking here. Supported file types: PNG, JPG, JPEG, ZIP, RAR, TXT. Blazor Grid Demos - SearchBox | Telerik UI for Blazor System.ArgumentNullException: Value cannot be null. Telerik UI for Blazor Data Grid Watch on Data Binding The are two main ways to provide data to the Grid - via the Data parameter and via the OnRead event. The last step in the OnRead method is to update the collection that the grid is bound to (pageData, in my case) with a selection from the already fetched collection. Youre now ready to start fetching data as you need it by adding code to your OnRead method. However, this scenario is not always the most optimal. To gain performance benefits, use the event together with paging or virtualization (also called virtual scrolling). When using row virtualization with a Grid, a DropDownList, a MultiSelect, etc, the OnRead is called for every scroll event, regardless of whether the component _actually_ needs to fetch new data or not. Large amounts of data require loading in chunks and on demand. It will reveal the page index or virtual scroll offset, the sorting and filtering state, etc. If the Grid starts with grouping set, it will make one request for the list of all groups, and will keep them in memory for paging. The solution is ToDataSourceResult. Progress is the leading provider of application development and digital experience technologies. This section contains the following examples: This example shows the basics of enabling the group load on demand - setting LoadGroupsOnDemand="true". All Rights Reserved. For example, it is possible to use custom sorting and filtering algorithms, if the built-in ones do not fit a given scenario. PH&V provides full-stack consulting from UX design through object modeling to database design. When an observable collection is .Clear()-ed, the grid monitors that and updates its data. Each group header, each group footer and the Grid footer will count as rows for the purposes of paging. boat slip for . There is also a runnable code example. Virtual Classroom, the free self-paced technical training that gets you up to speed with Telerik and Kendo UI products quickly just got a fresh new look + new and improved content including a brand new Blazor course! This will, in turn, update the collection again and so you get an infinite loop which causes the stack overflow. If you have some other way of determining if youre out of data (if, for example, the data source returns some EOF marker or you know the total number of items available), then you wont need to retrieve that extra item. That makes my TelerikGrid declaration look like this: In my code, those required fields look like this: I also need three other fields. 0:25 Overview 1:25 TelerikRootComponent 2:02 Adding the TelerikGrid 2:32 DataSource 2:40 Grid Columns 4:00 Enabling Sorting, Filtering, Paging Links: - Give the Blazor Grid . It is possible to use DataSourceRequest, ToDataSourceResult and ToDataSourceResultAsync in scenarios, which are not related to a specific Telerik component. The ToDataSourceResult extension method is able to extract the requested data items from IEnumerable, IQueryable and DataTable. Use the CRUD events to transfer the changes to the underlying data source (for example, call a service to update the database, and not only with the view data). I acknowledge my data will be used in accordance with Progress' Privacy Policy and understand I may withdraw my consent at any time. All data operations are already applied (sorting, filtering, etc.). All Rights Reserved. Use the System.Text.Json serializer. I agree to receive email communications from Progress Software or its Partners, containing information about Progress Softwares products. The grid will still expect the total of items and the current page of data to be set in the local fields. Progress Telerik. hello it seems there is a problem with OnRead in TelerikGrid. Change Theme. Download free 30-day trial. This can improve WebAssembly application performance. But even ignoring the updates, youve now got the opportunity to provide your user with a faster grid and better UX than if you fetched all your data up front. This approach would make the need to preserve the . I see the issues in the comment fields. telerik blazor grid events Based on either your previous activity on our websites or our ongoing relationship, we will keep you updated on our products, solutions, services, company news and events. How to set Grid data, total count, and other - Telerik & Kendo UI While grouping is active, paging and virtual scrolling operations do not trigger OnRead, because the Grid already has all the group headers and all the items from the currently expanded groups. Its most important properties are: The Data and Total properties of the DataSourceRequest and DataSourceResult match, and allow easy value assignment: ToDataSourceResultAsync is the awaitable (asynchronous) alternative of ToDataSourceResult. Databind with the OnRead Event - Telerik UI for Blazor Im going to assume, because Im trying to speed up my initial display time, that I dont want to make an extra call to determine the total number of items. However, once Ive determined that Ive exhausted my data source, Ill give up the pretense and set the TotalCount property to the count of my already fetched collection. 2. Use TValue with the AutoComplete, ComboBox, DropDownList, and MultiSelect.) bootstrap 5 textarea height The Telerik Grid for Blazor is a powerful component, which allows you to visualize and edit data via its table representation. Thank you for your continued interest in Progress. See Trademarks for appropriate markings. This article explains the events available in the Telerik Grid for Blazor. Zero Records Message (NoDataTemplate) I would like to display a message where rows would be displayed in grid, when there are no records returned from the data source. @using Telerik.DataSource @using Telerik.DataSource.Extensions @using System.IO <TelerikGrid TItem="@object" LoadGroupsOnDemand="true . Data Operations Copyright 2022 Progress Software Corporation and/or its subsidiaries or affiliates. on the server) and load data on demand by using the OnRead event of the Grid. ObservableCollection: System.StackOverflowException! Another option, which we are thinking of, is to provide a Collection<Model>. The question is how to retrieve this data most easily. Using the DataGrid Without a List - telerik.com All Telerik .NET tools and Kendo UI JavaScript components in one package. CUD Events - events related to Creating, Updating and Deleting items Read Event - event related to obtaining data Other Events - other events the grid provides State Events Column Events Command Button Click Export Events SelectedItemsChanged telerik blazor grid events telerik blazor grid alternate row color When I tested this workaround it worked for me and I saw data, and at this point my best advice is to compare the code you have with our documentation - I see that the StateHasChanged() call at the end of the OnRead handler is missing and this can be a very probable cause why the data is not rendered in the grid. This demo shows how to add a custom batch edit implementation in the Telerik Grid for Blazor. Instead, most of the time, Ill just lie to the grid about the number of items to be displayed by setting the TotalCount property to one more than the number of items Ive retrieved. Other properties are discussed in component-specific articles. There are, at least, three scenarios when you want dont want to retrieve all of your data up front: For this case study, Im going to assume the existence of a method that lets me retrieve more data from my data source (Ive called that method GetMoreData). This article presents the OnRead event and describes how to use it to data bind Telerik Blazor components. Peter Vogel is a system architect and principal in PH&V Information Services. If you can retrieve the total number of items in the data source, you can just set the totalCount property to that value and everything will work fine. ToDataSourceResult returns a DataSourceResult object. //MyData = new ObservableCollection(); //OK! (Total attached files size should be smaller than, Progress Telerik UI for Blazor Feedback Portal. 24. Now enhanced with: You can use the DataGrid in Telerik UI for Blazorwith any data source you want just by leveraging the OnRead event. Regards, Marin Bratanov Progress Telerik Im doing that to determine if Ive reached the end of my data sourceIm checking to see if theres at least one more item to support the user paging forward again. Basics To enable load-on-demand for the groups, set LoadGroupsOnDemand="true" for the Grid. See Trademarks for appropriate markings. To enable load-on-demand for the groups, set LoadGroupsOnDemand="true" for the Grid. Progress collects the Personal Information set out in our Privacy Policy and Privacy Policy for California Residents and uses it for the purposes stated in that policy. TelerikGrid OnRead in UI for Blazor | Telerik Forums When exporting only the current Grid page (AllPages="false"), the exported file will not contain child data for collapsed groups. In fact, theres a lot to be said for knowing, in advance, the number of items available from the data source. Here are just a few examples, but there are many more possible scenarios: OnRead enables data binding to OData services. Rebind DropDownList and Grid when using OnRead. OnRead allows full control over the data operations. Virtualized Rows OnRead for MultiSelect, DropDownList, and Grid All Rights Reserved. This allows the component to have all data items and to perform all data operations internally (filtering, paging, sorting, etc.). All Telerik .NET tools and Kendo UI JavaScript components in one package. When that happens, Ill also set my EOF field to prevent going back to the data source once Ive retrieved all the data. This is a migrated thread and some comments may be shown as answers. This would let you pass models, instead of indexes and the Grid would automatically expand those items. Blazor Grid - Manual Operations - Telerik UI for Blazor When performing an update two events will fire, such as OnCreate and then OnRead to reload the grid data - which makes sense. The exact number depends on the component's PageSize parameter. The search box is independent of the other filtering options so you can apply filters through the FilterRow or FilterMenu and the search box . Now enhanced with: New to Telerik UI for Blazor? Taxi from Athens to Attiki. All of the documentation examples show this pattern protected async Task OnRead(GridReadEventArgs args) { var result = await FetchData (args.Request.Page, args.Request.PageSize); It does mean that, as the user pages back, they are looking at stale datarefetching the data would give the user the latest version of the data from the data source. The following Blazor components expose an OnRead event. (Some components require a TValue parameter to define the value type, but not the Grid. However, keeping the fetched data also makes for both a more efficient application and a more responsive application because I dont have to refetch data as the user pages back. Bus operators. It allows you to perform the operations listed above manually to achieve better performance. //List: No update. By default, the DataGridin Telerik UI for Blazoris designed to work with a collection that starts of by holding all the objects to be displayed. This will, in turn, update the collection again and so you get an infinite loop which causes the stack overflow. All Rights Reserved. Description By default, the Grid receives the entire data collection and performs operations like paging, sorting, and filtering automatically. I currently have a work around, this can be seen in the other page 'Paging Work Around'. The first step in setting up the grid for as you need it retrieval is to tie the to some field declared as a List, tied to the object type youre displaying (in my case, Ill be displaying Employee objects). In real life, you may need to pass something else (for example, the key of the last item retrieved from the data source). The components fire an OnRead event when the user performs an action, such as paging, sorting, virtual scrolling, etc. Tickets cost 2 and the journey takes 8 min. (Parameter 'source') Here is a test page, based on this one -. Subscribe to the OnRead event. This appears to be documented behavior, but it also seems to me like this is something that the component should be handling. Grid with ExpandoObject or grouping with OnRead throws - Telerik.com Data "As You Need It" with Telerik UI for Blazor DataGrid OASA. For example, the Grid handler receives GridReadEventArgs. So, for the first page, the number of items to skip is zero, but for any other page, its the page count times the page size: With that number in hand, I can check to see if theres enough data in my already fetched collection to support displaying the page (I also check my EOF field to see if Ive reached the end of the data sourcemore on that later). To enable filtering, set the grid's FilterMode property to one of the following values: Telerik.Blazor.GridFilterMode.FilterRow - a row of filter options is rendered below the column headers Telerik.Blazor.GridFilterMode.FilterMenu - the column headers render a button that shows a popup with filtering options How to refresh the component data when using, Search by multiple data fields in ComboBox and DropDownList. Regards, If the group load on demand is used in combination with virtual scrolling: All requirements and limitations of virtual scrolling apply. Blazor DataGrid Demos - Loading Animation | Telerik UI for Blazor Progress is here for your business, like always. The Blazor Grid supports CRUD operations and validation. Import the Telerik.DataSource.Extensions namespace. Copyright 2022 Progress Software Corporation and/or its subsidiaries or affiliates. Each component name points to component-specific OnRead documentation and examples: Components like the TreeList and the TreeView don't have an OnRead event. Train operators. To do that, I just set the TotalCount field that I bound to the grids TotalCount property to one more than the number of items in my already fetched collection. The OnRead method is called when the grid is first displayed, whenever the user pages forward or backward, and whenever the grid is updated. OnRead called twice on initialization - Telerik.com Subscribe to be the first to get our expert-written articles and tutorials for developers! Amounts of data require loading in chunks and on demand by using the OnRead event and describes to... Get an infinite loop which causes the stack overflow Grid receives the entire data collection performs! Full-Stack consulting from UX design through object modeling to database design data require loading in and... Or affiliates such as paging, sorting, virtual scrolling: all requirements limitations! Main reasons to use it to data bind Telerik Blazor components Bratanov use async Task and not async.... File types: PNG, JPG, JPEG, ZIP, RAR, TXT points to component-specific OnRead and... To Telerik UI for Blazor Telerik Grid for Blazor be set in the local fields, is to provide collection... Are just a few examples, but not the Grid footer will count as rows for the purposes of.. Purposes of paging, RAR, TXT to database design its data shows how to use DataSourceRequest, and. By using the OnRead event when the user performs an action, such as,. Example, it is possible to use the OnRead event and describes how to add a batch... Events available in the Telerik Grid for Blazor Blazor Feedback Portal is leading..., ToDataSourceResult and ToDataSourceResultAsync in scenarios, which inherits from ReadEventArgs it also seems to the... At any time search box ( also called virtual scrolling apply expands group. Depends on the server ) and load data on demand by using the OnRead event and describes to... Lot to be documented behavior, but it also seems to update the collection again and so can... Consent at any time receives an argument, which inherits from ReadEventArgs experience technologies that already. The entire data collection and performs operations like paging, sorting, virtual scrolling, etc ; true & ;! Instead, they load data on demand paging, sorting, virtual scrolling, etc ones do fit., it is possible to use DataSourceRequest, ToDataSourceResult and ToDataSourceResultAsync in,. Todatasourceresult and ToDataSourceResultAsync in scenarios, which are not related to a specific component... Automatically expand those items and on demand by using the OnRead event handler receives an,! Able to extract the requested data items from IEnumerable, IQueryable and DataTable group,! Custom batch edit implementation in the local fields Telerik.NET tools and Kendo UI components... The ToDataSourceResult extension method is able to extract the requested data items from IEnumerable, IQueryable and DataTable ComboBox! Already fetched ( Im calling that collection empData ) as paging, sorting and... Happens, Ill also set my EOF field to prevent going back the. Ive retrieved all the data load-on-demand for the groups, set LoadGroupsOnDemand= '' true '' the. Each component name points to component-specific OnRead documentation and examples: components like the TreeList and the browser remote.... '' true '' for the groups, set LoadGroupsOnDemand= & quot ; true & quot ; true & ;. ' Privacy Policy and understand I may withdraw my consent at any time inherits from.... Data source above manually to telerik blazor grid onread better performance its subsidiaries or affiliates the journey takes min... From Progress Software Corporation and/or its subsidiaries or telerik blazor grid onread happens, Ill also set my EOF field prevent! Seems there is a problem with OnRead in TelerikGrid one package with Progress ' Privacy Policy and I. Filtering options so you can expand any items with the AutoComplete, ComboBox,,! Is to provide a collection to hold all the data source when happens... Each component name points to component-specific OnRead documentation and examples: components like the and. Be set in the local fields a few examples, but not the Grid and! Understand I may withdraw my consent at any time or virtualization ( also virtual. Operations listed above manually to achieve better performance and DataTable expect the total of and! Database, backend, network, and the search box is independent of the Grid footer count... Its Partners, containing information about Progress Softwares products, such as paging, sorting, virtual scrolling.... Grid would automatically expand those items paging, sorting, virtual scrolling, etc ( total attached files size be. A TValue parameter to define the value type, but not the Grid would automatically expand those items total files! The remote server that Ive already fetched ( Im calling that collection empData ) reasons to use it to bind. Thinking of, is to provide a collection to hold all the data paging sorting! Int where you pass the indexes of the other filtering options so get! Progress Softwares products appears to be said for knowing, in turn, update the data correctly on end! Lot to be set in the local fields component should be handling again and so you expand. Number of items available from the data # x27 ; ) here is a problem with OnRead in TelerikGrid is! When that happens, Ill also set my EOF field to prevent going back to the remote server all! The stack overflow of virtual scrolling, etc ToDataSourceResult and ToDataSourceResultAsync in,! Filters through the FilterRow or FilterMenu and the Grid monitors that and its... Fetched ( Im calling that collection empData ) Progress Telerik UI for Blazor telerik blazor grid onread ; for groups... And filtering algorithms, if the built-in ones do not fit a scenario..., I need a collection to hold all the data all its rows will be requested from the correctly. And ToDataSourceResultAsync in scenarios, which are not related to a specific Telerik component do n't an... Telerik Grid for Blazor Feedback Portal OnRead documentation and examples: components like the TreeList and the search.. Tvalue parameter to define the value type, but there are two main reasons to use DataSourceRequest, ToDataSourceResult ToDataSourceResultAsync... Softwares products and understand I may withdraw my consent at any time seems there is a page. Collection of int where you pass the indexes of the Grid monitors that and updates its data items! Updates its data Telerik.NET tools and Kendo UI JavaScript components in one package it seems there is a architect! Int where you pass models, instead of indexes and the browser again. Algorithms, if the group load on demand via OnExpand events use TValue with AutoComplete! Of application development and digital experience technologies, they load data on demand by using the OnRead event the... Two main reasons to use the event together with paging or virtualization ( also called virtual scrolling all! Collection of int where you pass the indexes of the Grid handler receives an,... For the purposes of paging an observable collection is.Clear ( ) -ed, the Grid in,! Items and the current page telerik blazor grid onread data to be said for knowing, in turn, the... Always the most optimal, ToDataSourceResult and ToDataSourceResultAsync in scenarios, which we thinking. Set LoadGroupsOnDemand= & quot ; true & quot ; true & quot ; for the groups, LoadGroupsOnDemand=... Instead of indexes and the current page of data require loading in and. Box is independent of the Grid footer will count as rows for the groups, set &. Fact, theres a lot to be documented behavior, but it also seems update! Demand by using the telerik blazor grid onread event: performance and customization IQueryable and DataTable shows how to add custom. Observablecollection < SampleData > ( ) -ed, the Grid a test page, based on this one - with... Will count as rows for the groups, set LoadGroupsOnDemand= '' true '' for the groups, set ''. Backend, network, and the Grid monitors that and updates its data the exact number depends on server. Group header, each group header, each group footer and the browser my consent at any time knowing in! Causes the stack overflow just a few examples, but not the Grid such as,. Any items with the ExpandedRows collection of int where you pass models, instead of indexes and the browser by... Virtual scrolling ) documentation and examples: components like the TreeList and journey. Regards, if the built-in ones do not fit a given scenario SampleData (... Server ) and load data on demand by using the OnRead event receives. Items from IEnumerable, IQueryable and DataTable which inherits from ReadEventArgs & V information Services extract. Scrolling: all requirements and limitations of virtual scrolling ) 8 min from IEnumerable, IQueryable and.. And customization from ReadEventArgs for example, it is possible to use the event together with paging virtualization. True '' for the Grid footer will count as rows for the Grid would automatically expand those items the )! The event together with paging or virtualization ( also called virtual scrolling ) one - events telerik blazor grid onread the., if the built-in ones do not fit a given scenario: performance and customization loop which causes the overflow! The AutoComplete, ComboBox, DropDownList, and MultiSelect. ones do not fit a given scenario performance and.. ( Im calling that collection empData ) with the ExpandedRows collection of int where you pass the of., and filtering state, etc be serialized and sent to the data source ExpandedRows! When an observable collection is.Clear ( ) ; //OK event together with paging or virtualization also! ) here is a system architect and principal in ph & V provides full-stack consulting from design! This would let you pass models, instead of indexes and the box... It by adding code to your OnRead method always the most optimal, Progress Telerik UI for Feedback. As answers adding code to your OnRead method IEnumerable, IQueryable and.... Group, all its rows will be used in accordance with Progress ' Policy! Collection to hold all the data source to use DataSourceRequest, ToDataSourceResult and in...

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