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Displaying and editing many-to-many relational data in a WPF DataGrid Magnus Montin
The post is devoted to the WPF gridview with a dynamically-defined number of rows and columns but all cells have the same width and height. For example, such a grid could be used in chess or checkers games for 8×8 field. The user data grid column definition is stored in the UserRolesColumns collection.
Instead of individual updates for each table, we can use a single, unified approach. This involves creating a view or stored procedure that combines data from relevant tables, simplifying data access and manipulation. The WPF application then interacts with this consolidated data source. This streamlined approach minimizes the number of database interactions, leading to improved performance, especially when dealing with large datasets. The use of parameterized queries further enhances security by preventing SQL injection vulnerabilities. By centralizing data access through a well-defined interface, the application’s maintainability is greatly improved.
Dynamic Columns in a WPF DataGrid Control (Part
The drawback of this solution is that GUI components spilled over into the ViewModel layer. In the next article, I will show a solution that implements the same application, but with a more strict separation of business logic and GUI controls into their respective layers. As an added bonus (and to prevent extra state logic) I added the functionality that the CheckBox control is not shown in the user data grid new item row. The DataGridCheckBoxColumn style has to be modified, and the Visibility flag of the CheckBox has to be set, depending on the contents of the DataGridCell. If the data row is the new item row, then it has a NewItemPlaceHolder. A converter is used to get this information and it is mapped to the CheckBox’s Visibility flag.
- It is a straight forward MVVM implementation where the dynamic column handling is done in the view-model layer.
- At the contrast of the Grid object witch is defined in the System.Windows.Controls, the table object is defined in the System.Windows.Documents namespace.
- In this case, it would be a boolean property in the user data row, which represents the user to role assignment.
- When you want to pass a parameter to a command from a view you do so by using the CommandParameter property.
- I guess it isn’t very clear until now; therefore, I invite you to parse the following representation.
This involves defining constraints on database columns, such as data types, lengths, and nullability, and implementing validation logic in the WPF application before submitting data to the database. This two-pronged approach prevents invalid data from entering the system, maintaining data integrity and enhancing the overall reliability of the application. The combination of database constraints and application-level validation provides a robust defense against invalid data, minimizing errors and ensuring data accuracy. Regular testing and validation procedures further solidify data integrity and contribute to a more stable and reliable application.
As you can see, I dynamically create a Binding, and use the index of the column in my model as the binding path. When building an application, I might not have the luxury of creating model classes to represent the objects I’ll be rendering on screen, because they are dynamic. If I don’t know the shape of my data, I can use a meta model (a model of the final model) to represent it.
The Data Model
The logic searches for the CheckBox’s DataGridCell and gets the user and role instances that belong to it. It will add or delete the user-role entry depending on the CheckBox.IsChecked state and whether a UserRoleRow is already present. I tried with a RadGridView (Telerik) but rows are only updatable by ItemsSource property, and like I don’t know how many columns will be, I can’t create an object which represents the table (x properties for x columns). Let’s explore efficient ways to manage your SQL Server data within a WPF application. We’ll focus on using ObservableCollections to keep your WPF SQL Server DataGrid dynamically updated, reflecting database changes seamlessly. This ensures a responsive user interface and avoids common pitfalls.
The DataGridCheckBoxColumn binds the check box control to a (nullable) boolean property of the data in the row that it is displaying. In this case, it would be a boolean property in the user data row, which represents the user to role assignment. Since there is no such property in the UserTable definition, another solution has to be implemented. Instead of binding to the check box control, a value converter is instantiated and bound to the DataGridCell that will contain the CheckBox control. The Binding definition in the AddRoleColumn method shown above contains an assignment to the value converter. The relative source of the bound control is set to the DataGridCell, found as an ancestor of the CheckBox control (the binding is defined on the CheckBox level).
This example showcases how to retrieve data from multiple tables using a JOIN operation. This is essential for retrieving related data from different tables in a database. This code snippet demonstrates adding a new product to the Products table and retrieving its newly generated ID using SCOPE_IDENTITY(). A many-to-many relationship is one where two data tables or entities have multiple rows that are connected to one or more rows in the other table.
Dynamic PostgreSQL Pivot Table for Patient Treatment Summary
Also, other implementation for cells could be used; for example, 2-dimensional array of cells ICellViewModels works well. Note that the XAML markup for the view contains only an empty DataGrid and the columns and bindings are defined in code. This is perfectly acceptable and does not break the MVVM pattern since all code is view related. The MVVM design pattern is about separating application logic from your view logic and not necessarily about eliminating code out of the views. The reason why this is done in C# code instead of static XAML markup is of course that the number of groups (columns) is dynamic and may vary over time. For example, if you add another row to the Group database table, you want another column representing this new group to show up in the DataGrid without any changes to the code.
This approach significantly improves the overall efficiency and maintainability of the application, reducing development time and improving the user experience. The post showcases a WPF datagrid with dynamic columns where the number of rows and columns is defined but all cells have the same size. For the command of the view model to know what to do when it gets executed, you have to pass it some parameters. It needs to know which Group object that is to be added or removed to or from which User object. When you want to pass a parameter to a command from a view you do so by using the CommandParameter property. If you require the ability to change the relationships between the entities, you somehow need to add or remove groups from the Groups collection property of the corresponding User object when the user checks or unchecks a CheckBox.
Troubleshooting a Decimal-data error in an RPGLE program using embedded SQL. This guide covers various join strategies and indexing techniques for efficient data retrieval. Troubleshooting a Spring Boot pagination issue with Pageable in Spring Boot 3.1.0 and Hibernate 6.2. Data retrieval returns the entire dataset instead of the requested page.
Note however that as a converter is not part of the visual tree, it doesn’t have any DataContext and this means that you have to get or inherit this from somewhere. You can read this external article published on the CodeProject for some ways of doing this if you decide to take this approach. Dynamic grid is implemented as user control that contains DataGrid control bound to observable collection of collections of cell view models. This section delves into efficient techniques https://traderoom.info/displaying-data-in-tables-with-wpf-s-datagrid/ for manipulating data within a SQL Server database, seamlessly integrated with a WPF application using C#.
The post is devoted to the Wpf datagrid with cells that have defined fixed size but a number of rows and columns is updated dynamically in order to fill all available space. For example, such grid could be used in games at infinite 2D field or implementation of cellular automaton. A common challenge involves managing multiple tables simultaneously.