# Sorting and Filtering > Filter and sort the rows of merge blocks in WPF: FilterInstruction and SortingInstruction, Apply, the WPF FilterAndSortDialog and BlockMergingCondition. - **Product:** TX Text Control .NET for WPF - **Section:** Documentation - **Kind:** Topic - **Path:** TX Text Control .NET for WPF > Mail Merge and Reporting > Sorting and Filtering - **4211 words** - **Web URL:** https://docs.textcontrol.com/tx-text-control-dotnet-wpf/mail-merge/sorting-filtering/ - **LLMs URL:** https://docs.textcontrol.com/tx-text-control-dotnet-wpf/mail-merge/sorting-filtering/llms.txt - **LLMs-Full URL:** https://docs.textcontrol.com/tx-text-control-dotnet-wpf/mail-merge/sorting-filtering/llms-full.txt --- Data from an ERP system or a web service seldom has the order or the selection a document needs. Instead of reshaping it in code before each merge, attach sorting and filter instructions to the merge block: `MailMerge` sorts and filters the rows of the block while it merges, and the instructions stay with the template. In a WPF application, users edit them in a WPF dialog box, and your code sets them when it inserts a block, changes them on existing blocks and adds conditions that decide whether a nested block is merged at all. The block tools of the Reporting tab are described in [Merge Blocks](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/mail-merge/blocks/llms-full.txt). The code uses *invoice.json* with its `Items` array, loaded into the Reporting tab `ribbonReportingTab1`, and the orders template of [Nested Blocks and Master-Detail Reports](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/mail-merge/nested-blocks/llms-full.txt). The handlers go into *MainWindow.xaml.cs*, each connected to a button in *MainWindow.xaml*. ### How Sorting and Filtering Works Three lists of a [MergeBlockInfo](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-datasources/mergeblockinfo/llms-full.txt), the description of a block, hold the instructions: | Property | Contains | Effect | |---|---|---| | [Filters](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-datasources/mergeblockinfo/filters-property/llms-full.txt) | `FilterInstruction` objects | Only the rows that match are merged | | [SortingInstructions](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-datasources/mergeblockinfo/sortinginstructions-property/llms-full.txt) | `SortingInstruction` objects | The rows are merged in this order | | [BlockMergingCondition](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-datasources/mergeblockinfo/blockmergingcondition-property/llms-full.txt) | `FilterInstruction` objects | The block is merged only if its parent record matches | A list that is empty or `null` means no filter, no sorting or no condition. Your code passes the lists with a new block to `InsertMergeBlock`, or changes them on an existing block and stores them with [Apply](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-datasources/mergeblockinfo/apply-method/llms-full.txt); the dialog box stores them itself. A filter changes what the merged table shows. Without a filter, a block lists every row of an order: ![A merged table with fifteen order rows and line totals from 20.75 to 8,099.98 dollars.](https://docs.textcontrol.com/assets/img/tx-text-control-dotnet-wpf/merge-block-rows-unfiltered.880ff307.webp) With a filter that keeps rows whose `LineTotal` is greater than 1000, the same block lists eight rows: ![The same merged table with eight rows, all with line totals above 1,000 dollars.](https://docs.textcontrol.com/assets/img/tx-text-control-dotnet-wpf/merge-block-rows-filtered.1ca5fde6.webp) ### Filter Instructions A [FilterInstruction](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-datashaping/filterinstruction/llms-full.txt) compares a column of each row with a value. The [constructor](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-datashaping/filterinstruction/constructor/llms-full.txt) takes the column name, a relational operator, the value and, optionally, a logical operator: | Operator | A row matches when the column value | |---|---| | `Equals`, `NotEqual` | Is equal or not equal to the value | | `LessThan`, `LessThanOrEqualTo` | Is less than, or less than or equal to, the value | | `GreaterThan`, `GreaterThanOrEqualTo` | Is greater than, or greater than or equal to, the value | | `IsBlank`, `IsNotBlank` | Is null or empty, or is not | - **Numeric or string comparison.** A value that can be parsed as a number is compared numerically with a column of numbers; everything else is compared as strings. [Culture](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-datashaping/filterinstruction/culture-property/llms-full.txt) parses the numbers and defaults to the invariant culture. - **Combined instructions.** [LogicalOperator](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-datashaping/filterinstruction/logicaloperator-property/llms-full.txt) connects an instruction with the previous one by `And` or `Or`; constructors without it use `And`. - **Blank checks.** `IsBlank` and `IsNotBlank` need no value; use the constructor with the column name and the operator only. The blog article [MailMerge: Using Filters to Remove Unwanted Rows](https://www.textcontrol.com/blog/2019/06/04/mailmerge-using-filters-to-remove-unwanted-rows/) drops a total row that the data delivers with the line items. ### Sorting Instructions A [SortingInstruction](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-datashaping/sortinginstruction/llms-full.txt) sorts by one column. Its [constructor](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-datashaping/sortinginstruction/constructor/llms-full.txt) takes the column name and `SortOrder.Ascending` or `SortOrder.Descending`, ascending when left out. With several instructions, the rows are sorted by the first column, then by the next. The handlers below need these `using` directives in *MainWindow.xaml.cs*: ```csharp using System.Collections.Generic; using System.Linq; using TXTextControl; using TXTextControl.DocumentServer; using TXTextControl.DocumentServer.DataShaping; using TXTextControl.DocumentServer.DataSources; using TXTextControl.DocumentServer.WPF; ``` ### Set Instructions When Inserting a Block This handler inserts an `Items` block that keeps items with a price of at least 200 and a description, the highest price first: ```csharp private void insertFilteredItemsButton_Click(object sender, RoutedEventArgs e) { MergeBlockInfo itemsBlock = new MergeBlockInfo("Items") { ColumnNames = new List { "Description", "Quantity", "Price" }, // Only items with a price of at least 200 and a description Filters = new List { new FilterInstruction("Price", RelationalOperator.GreaterThanOrEqualTo, 200), new FilterInstruction("Description", RelationalOperator.IsNotBlank) }, // The highest price first, then by description SortingInstructions = new List { new SortingInstruction("Price", SortOrder.Descending), new SortingInstruction("Description") } }; ribbonReportingTab1.DataSourceManager.InsertMergeBlock(textControl1, itemsBlock, new MergeBlockSettings(BlockTemplateType.TableRow, true)); } ``` With the data of *invoice.json*, only *Training*, at 480.00, passes the price filter, so the merged table has one row. An `Or` connection needs the logical operator as fourth parameter: `new FilterInstruction("Quantity", RelationalOperator.GreaterThan, 1, LogicalOperator.Or)`. ### Change the Block at the Input Position To change an existing block, create a `MergeBlockInfo` from its subtext part, replace a list and call `Apply`. This handler sorts the block at the input position by price: ```csharp private void sortCurrentBlockButton_Click(object sender, RoutedEventArgs e) { SubTextPart subTextPart = textControl1.SubTextParts.GetItem(); if (subTextPart == null || !DataSourceManager.IsMergeBlock(subTextPart)) { MessageBox.Show(this, "Place the input position in a merge block."); return; } MergeBlockInfo mergeBlockInfo = new MergeBlockInfo(subTextPart) { // Replace the sorting instructions: the lowest price first SortingInstructions = new List { new SortingInstruction("Price", SortOrder.Ascending) } }; // Store the change in the block mergeBlockInfo.Apply(); } ``` - [SubTextParts.GetItem](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol/subtextpartcollection/getitem-method/llms-full.txt) returns the innermost subtext part at the input position of the WPF `TextControl`; [DataSourceManager.IsMergeBlock](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-datasources/datasourcemanager/ismergeblock-method/llms-full.txt) checks that it is a block. - The [MergeBlockInfo constructor](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-datasources/mergeblockinfo/constructor/llms-full.txt) reads the block and its instructions; a list is `null` when the block has none of that kind. - Only `Apply` writes the change into the block, together with the other lists. Nested blocks aren't affected; call `Apply` for each changed block. Existing instructions can be read from [ColumnName](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-datashaping/filterinstruction/columnname-property/llms-full.txt), [ComparisonOperator](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-datashaping/filterinstruction/comparisonoperator-property/llms-full.txt) and [CompareTo](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-datashaping/filterinstruction/compareto-property/llms-full.txt) of a filter and [OrderBy](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-datashaping/sortinginstruction/orderby-property/llms-full.txt) and [SortOrder](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-datashaping/sortinginstruction/sortorder-property/llms-full.txt) of a sorting instruction. ### Let Users Edit the Instructions [FilterAndSortDialog](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-wpf/filterandsortdialog/llms-full.txt) of the namespace `TXTextControl.DocumentServer.WPF` is a WPF window in which users define filters and sorting instructions for a block. The following handler opens it for the block at the input position, filled with the block's current instructions: ```csharp private void filterAndSortButton_Click(object sender, RoutedEventArgs e) { SubTextPart subTextPart = textControl1.SubTextParts.GetItem(); if (subTextPart == null || !DataSourceManager.IsMergeBlock(subTextPart)) { MessageBox.Show(this, "Place the input position in a merge block."); return; } MergeBlockInfo mergeBlockInfo = new MergeBlockInfo(subTextPart); // The columns of the block's table fill the drop-downs of the dialog DataTableInfo table = ribbonReportingTab1.DataSourceManager.DataTables[mergeBlockInfo.TableName]; if (table == null) { MessageBox.Show(this, "The loaded data source has no table " + mergeBlockInfo.TableName + "."); return; } FilterAndSortDialog dialog = new FilterAndSortDialog(table) { Owner = this, // Show the instructions the block already has Filters = mergeBlockInfo.Filters?.ToArray(), SortingInstructions = mergeBlockInfo.SortingInstructions?.ToArray() }; // ShowDialog returns true when the user clicks OK if (dialog.ShowDialog() == true) { // Write the instructions into the block dialog.StoreBlockMetaData(subTextPart); } } ``` The code works as follows: - The [FilterAndSortDialog constructor](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-wpf/filterandsortdialog/constructor/llms-full.txt) takes the [DataTableInfo](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-datasources/datatableinfo/llms-full.txt) of the block's data, looked up by name in `DataTables`, or the column names as a string array. - [Filters](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-wpf/filterandsortdialog/filters-property/llms-full.txt) and [SortingInstructions](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-wpf/filterandsortdialog/sortinginstructions-property/llms-full.txt) are arrays that fill the dialog box when it opens and hold the user's instructions when it closes. - `Owner` keeps the dialog box in front of the main window; `ShowDialog` returns a nullable `bool`, as for every WPF window. - [StoreBlockMetaData](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver-wpf/filterandsortdialog/storeblockmetadata-method/llms-full.txt) writes the instructions into the block and throws an exception for a subtext part that isn't a merge block. ### Merge a Block Only for Matching Parent Rows A merging condition is checked one level up, against the parent record of a nested block: when the parent record doesn't match, the block isn't merged. With the orders template of Nested Blocks in `textControl1`, this handler restricts the `articles` block to the order with the ID 123: ```csharp private void articlesConditionButton_Click(object sender, RoutedEventArgs e) { SubTextPart articlesPart = textControl1.SubTextParts.GetItem(MailMerge.MergeBlockNamePrefix + "articles"); if (articlesPart == null) { MessageBox.Show(this, "The template has no articles block."); return; } MergeBlockInfo articles = new MergeBlockInfo(articlesPart) { // Checked against the parent row, the current order BlockMergingCondition = new List { new FilterInstruction("id", RelationalOperator.Equals, 123) } }; articles.Apply(); } ``` `GetItem` with a name finds a subtext part by its name, `txmb_` from [MergeBlockNamePrefix](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol-documentserver/mailmerge/mergeblocknameprefix-property/llms-full.txt) plus the block name, and returns `null` when there is none. After a merge with *orders.json*, order 123 shows its article and order 321 has no articles. The blog article [MailMerge: Conditional Rendering of Merge Blocks](https://www.textcontrol.com/blog/2018/11/28/mailmerge-conditional-rendering-of-merge-blocks/) contrasts conditions with blocks that are removed for missing data. ### Where the Instructions Are Stored The instructions are saved in the block's subtext part, as a JSON string in its [Data](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/reference/txtextcontrol/subtextpart/data-property/llms-full.txt) property, whether `Apply`, `InsertMergeBlock` or the dialog box wrote them. Save such templates in the TX Text Control format, which keeps this data with the blocks. The blog article [Mail Merge: Conditional Data Shaping in Merge Blocks](https://www.textcontrol.com/blog/2023/05/03/mail-merge-conditional-data-shaping-in-merge-blocks/) shows that JSON for a block with a merging condition. ### Next Steps - [Conditional Content](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/mail-merge/conditional-content/llms-full.txt): include or leave out whole sections depending on the data. - [Nested Blocks and Master-Detail Reports](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/mail-merge/nested-blocks/llms-full.txt): the master-detail templates that merging conditions work with. - [Reporting Ribbon and WPF Dialog Boxes](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/mail-merge/ribbon-dialogs/llms-full.txt): the other dialog boxes of the Reporting tab. - The blog article [Filtering and Sorting Repeating Blocks in MailMerge using C#](https://www.textcontrol.com/blog/2025/08/21/filtering-and-sorting-repeating-blocks-in-mailmerge-using-csharp/): inventory reports built with filters and sorting. --- ## Nearby - **Previous:** [Conditional Content](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/mail-merge/conditional-content/llms-full.txt) - **Next:** [Formatting and Styling](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/mail-merge/styling/llms-full.txt)