Added How Tos for c# scripting.

content/features/Useful-script-snippets.md

@@ -2,6 +2,7 @@
 uid: useful-script-snippets
 title: Useful script snippets
 author: Daniel Otykier
+updated: 2026-04-10
 applies_to:
   products:
     - product: Tabular Editor 2
@@ -21,6 +22,9 @@ Here's a collection of small script snippets to get you started using the [Advan
 
 Also, make sure to check out our script library @csharp-script-library, for some more real-life examples of what you can do with the scripting capabilities of Tabular Editor.
 
+> [!TIP]
+> For structured, pattern-by-pattern reference material on C# scripting and Dynamic LINQ, see the [Scripting Patterns](/how-tos/scripting-navigate-tom-hierarchy) how-to series. For the complete TOM wrapper API, see the @api-index.
+
 ***
 
 ## Create measures from columns

content/how-tos/scripting-add-clone-remove-objects.md

@@ -0,0 +1,206 @@
+---
+uid: how-to-add-clone-remove-objects
+title: How to Add, Clone and Remove Objects
+author: Morten Lønskov
+updated: 2026-04-10
+applies_to:
+  products:
+    - product: Tabular Editor 2
+      full: true
+    - product: Tabular Editor 3
+      full: true
+---
+# How to Add, Clone and Remove Objects
+
+C# scripts can create new model objects, clone existing ones and delete objects. This article covers the Add, Clone and Delete patterns.
+
+## Quick reference
+
+```csharp
+// Add objects -- all parameters after the first are optional.
+// See sections below for parameter details.
+table.AddMeasure("Name", "DAX Expression", "Display Folder");
+table.AddCalculatedColumn("Name", "DAX Expression", "Display Folder");
+table.AddDataColumn("Name", "SourceColumn", "Display Folder", DataType.String);
+table.AddHierarchy("Name", "Display Folder", col1, col2, col3);
+Model.AddCalculatedTable("Name", "DAX Expression");
+Model.AddPerspective("Name");
+Model.AddRole("Name");
+Model.AddTranslation("da-DK");
+
+// Relationships
+var rel = Model.AddRelationship();
+rel.FromColumn = Model.Tables["Sales"].Columns["ProductKey"];   // many (N) side
+rel.ToColumn = Model.Tables["Product"].Columns["ProductKey"];   // one (1) side
+
+// Clone
+var clone = measure.Clone("New Name");                         // same table
+var clone = measure.Clone("New Name", true, targetTable);      // different table
+
+// Delete (always materialize with ToList() before modifying a collection in a loop)
+measure.Delete();
+table.Measures.Where(m => m.IsHidden).ToList().ForEach(m => m.Delete());
+```
+
+## Adding measures
+
+`AddMeasure()` creates and returns a new `Measure` on a table. The first parameter is the name, the second is a DAX expression and the third is the display folder. All parameters except the first are optional.
+
+Capture the returned object in a variable to set additional properties. This pattern is the same across all `Add*` methods.
+
+```csharp
+var table = Model.Tables["Sales"];
+
+// Create a measure and set properties on the returned object
+var m = table.AddMeasure(
+    "Revenue",                   // name
+    "SUM('Sales'[Amount])"       // DAX expression
+);
+m.FormatString = "#,##0.00";
+m.Description = "Total sales amount";
+
+// With display folder
+var m2 = table.AddMeasure(
+    "Cost",                      // name
+    "SUM('Sales'[Cost])",        // DAX expression
+    "Financial"                  // display folder
+);
+```
+
+## Adding columns
+
+```csharp
+// Calculated column -- first parameter is the name, second is a DAX expression
+var cc = table.AddCalculatedColumn(
+    "Profit",                              // name
+    "'Sales'[Amount] - 'Sales'[Cost]"      // DAX expression
+);
+cc.DataType = DataType.Decimal;
+cc.FormatString = "#,##0.00";
+
+// Data column -- maps to a source column in the partition query
+var dc = table.AddDataColumn(
+    "Region",              // name
+    "RegionName",          // source column name
+    "Geography",           // display folder
+    DataType.String        // data type
+);
+```
+
+> [!WARNING]
+> Adding a data column does not modify the table's partition query. You must update the M expression or SQL query separately to include a source column that matches the `sourceColumn` parameter.
+
+## Adding hierarchies
+
+The `levels` parameter is variadic. Pass any number of columns in a single call to create the corresponding levels automatically.
+
+```csharp
+var dateTable = Model.Tables["Date"];
+var h = dateTable.AddHierarchy(
+    "Calendar",                        // name
+    "",                                // display folder
+    dateTable.Columns["Year"],         // level 1
+    dateTable.Columns["Quarter"],      // level 2
+    dateTable.Columns["Month"]         // level 3
+);
+```
+
+Or add levels one at a time:
+
+```csharp
+var h = dateTable.AddHierarchy("Fiscal");
+h.AddLevel(dateTable.Columns["FiscalYear"]);
+h.AddLevel(dateTable.Columns["FiscalQuarter"]);
+h.AddLevel(dateTable.Columns["FiscalMonth"]);
+```
+
+## Adding calculated tables
+
+```csharp
+var ct = Model.AddCalculatedTable(
+    "DateKey List",                    // name
+    "VALUES('Date'[DateKey])"          // DAX expression
+);
+```
+
+## Adding relationships
+
+`AddRelationship()` creates and returns an empty relationship. You must set the columns explicitly.
+
+`FromColumn` is the many (N) side and `ToColumn` is the one (1) side. Tabular Editor does not detect the direction automatically. A useful mnemonic: F for From, F for Fact table (the many side).
+
+New relationships default to `CrossFilteringBehavior.OneDirection` and `IsActive = true`. Set these only if you need a different value.
+
+```csharp
+var rel = Model.AddRelationship();
+rel.FromColumn = Model.Tables["Sales"].Columns["ProductKey"];   // many side (fact)
+rel.ToColumn = Model.Tables["Product"].Columns["ProductKey"];   // one side (dimension)
+
+// Only set these if you need non-default values:
+// rel.CrossFilteringBehavior = CrossFilteringBehavior.BothDirections;
+// rel.IsActive = false;
+```
+
+## Cloning objects
+
+`Clone()` creates a copy with all properties, annotations and translations.
+
+```csharp
+// Clone within the same table
+var original = Model.AllMeasures.First(m => m.Name == "Revenue");
+var copy = original.Clone("Revenue Copy");
+
+// Clone to a different table (with translations)
+var copy2 = original.Clone("Revenue Copy", true, Model.Tables["Reporting"]);
+```
+
+## Generating measures from columns
+
+A common pattern: iterate selected columns and create derived measures. Note the use of `DaxObjectFullName` which returns the fully qualified, properly quoted DAX reference (e.g., `'Sales'[Amount]`) to avoid quoting errors.
+
+```csharp
+foreach (var col in Selected.Columns)
+{
+    var m = col.Table.AddMeasure(
+        "Sum of " + col.Name,
+        "SUM(" + col.DaxObjectFullName + ")",
+        col.DisplayFolder
+    );
+    m.FormatString = "0.00";
+    col.IsHidden = true;
+}
+```
+
+## Deleting objects
+
+Call `Delete()` on any named object to remove it. When modifying a collection in a loop (deleting, adding or moving objects), always call `.ToList()` first to materialize a snapshot.
+
+```csharp
+// Delete a single object
+Model.AllMeasures.First(m => m.Name == "Temp").Delete();
+
+// Delete multiple objects safely
+Model.AllMeasures
+    .Where(m => m.HasAnnotation("DEPRECATED"))
+    .ToList()
+    .ForEach(m => m.Delete());
+```
+
+## Common pitfalls
+
+> [!WARNING]
+> - Always call `.ToList()` or `.ToArray()` before modifying objects in a loop. Without it, modifying the collection during iteration causes: `"Collection was modified; enumeration operation may not complete."`
+> - `AddRelationship()` creates an incomplete relationship. You must assign both `FromColumn` and `ToColumn` before the model validates.
+> - `Column` is abstract, but you can access all base properties (`Name`, `DataType`, `FormatString`, `IsHidden`) without casting. Only cast to a subtype for type-specific properties.
+> - `Clone()` copies all metadata including annotations, translations and perspective membership. Remove unwanted metadata after cloning.
+
+## See also
+
+- @useful-script-snippets
+- @script-create-sum-measures-from-columns
+- @how-to-navigate-tom-hierarchy
+- @how-to-use-selected-object
+- (xref:TabularEditor.TOMWrapper.Measure) -- Measure API reference
+- (xref:TabularEditor.TOMWrapper.Column) -- Column API reference
+- (xref:TabularEditor.TOMWrapper.Hierarchy) -- Hierarchy API reference
+- (xref:TabularEditor.TOMWrapper.SingleColumnRelationship) -- Relationship API reference

content/how-tos/scripting-check-object-types.md

@@ -0,0 +1,107 @@
+---
+uid: how-to-check-object-types
+title: How to Check Object Types
+author: Morten Lønskov
+updated: 2026-04-10
+applies_to:
+  products:
+    - product: Tabular Editor 2
+      full: true
+    - product: Tabular Editor 3
+      full: true
+---
+# How to Check Object Types
+
+The TOM hierarchy uses inheritance. `Column` is an abstract base with subtypes `DataColumn`, `CalculatedColumn` and `CalculatedTableColumn`. `Table` has subtypes `CalculatedTable` and `CalculationGroupTable`. Use the base type when working with shared properties like `Name`, `Description`, `IsHidden`, `FormatString` or `DisplayFolder`. Cast to a concrete subtype when you need type-specific properties, such as `Expression` on `CalculatedColumn` or `SourceColumn` on `DataColumn`.
+
+## Quick reference
+
+```csharp
+// Pattern matching -- checks type AND casts in one step
+if (col is CalculatedColumn cc)
+    Info(cc.Expression);  // Expression is only on CalculatedColumn, not base Column
+
+// Filter a collection by type
+var calcCols = Model.AllColumns.OfType<CalculatedColumn>();
+var calcGroups = Model.Tables.OfType<CalculationGroupTable>();
+
+// Runtime type name (use only for display/logging, not for logic)
+string typeName = obj.GetType().Name;   // "DataColumn", "Measure", etc.
+```
+
+> [!NOTE]
+> Pattern matching with variable declaration (`col is CalculatedColumn cc`) requires the Roslyn compiler in Tabular Editor 2. Configure it under **File > Preferences > General > Compiler path**. See [Compiling with Roslyn](xref:advanced-scripting#compiling-with-roslyn) for details. Tabular Editor 3 supports this by default.
+
+## Type hierarchy
+
+The key inheritance relationships in the TOM wrapper:
+
+| Base type | Subtypes |
+|---|---|
+| (xref:TabularEditor.TOMWrapper.Column) | (xref:TabularEditor.TOMWrapper.DataColumn), (xref:TabularEditor.TOMWrapper.CalculatedColumn), (xref:TabularEditor.TOMWrapper.CalculatedTableColumn) |
+| (xref:TabularEditor.TOMWrapper.Table) | (xref:TabularEditor.TOMWrapper.CalculatedTable), (xref:TabularEditor.TOMWrapper.CalculationGroupTable) |
+| (xref:TabularEditor.TOMWrapper.Partition) | (xref:TabularEditor.TOMWrapper.MPartition), (xref:TabularEditor.TOMWrapper.EntityPartition), (xref:TabularEditor.TOMWrapper.PolicyRangePartition) |
+| (xref:TabularEditor.TOMWrapper.DataSource) | (xref:TabularEditor.TOMWrapper.ProviderDataSource), (xref:TabularEditor.TOMWrapper.StructuredDataSource) |
+
+## Filtering collections by type
+
+`OfType<T>()` works on any collection and returns a filtered sequence containing only items that are the specified type. It returns an empty sequence if no items match.
+
+```csharp
+// All calculated columns in the model (empty if model has none)
+var calculatedColumns = Model.AllColumns.OfType<CalculatedColumn>();
+
+// All M partitions (Power Query)
+var mPartitions = Model.AllPartitions.OfType<MPartition>();
+
+// All calculation group tables
+var calcGroups = Model.Tables.OfType<CalculationGroupTable>();
+
+// All regular tables (exclude calculation groups and calculated tables)
+var regularTables = Model.Tables.Where(t => t is not CalculationGroupTable && t is not CalculatedTable);
+```
+
+## Pattern matching with is
+
+Pattern matching does two things: it checks whether a value is a given type and optionally casts it into a new variable. The form `x is Type xx` asks "is `x` of type `Type`?" and, if true, gives you `xx` as a variable of that exact type.
+
+This is equivalent to:
+
+```csharp
+if (col is CalculatedColumn)
+{
+    var cc = (CalculatedColumn)col; // explicit cast
+    // use cc...
+}
+```
+
+If you only need the boolean check, use `x is Type` without the variable. If you also need subtype-specific properties, use `x is Type xx`.
+
+```csharp
+foreach (var col in Model.AllColumns)
+{
+    // Expression is only available on CalculatedColumn, not the base Column type
+    if (col is CalculatedColumn cc)
+        Info($"{cc.Name}: {cc.Expression}");
+    else if (col is DataColumn dc)
+        Info($"{dc.Name}: data column in {dc.Table.Name}");
+}
+```
+
+## Dynamic LINQ equivalent
+
+In BPA rules, type filtering is handled by the rule's **Applies to** scope. Set it to the target object type (e.g., **Calculated Columns**) rather than filtering by type in the expression. No C#-style type casting is available in Dynamic LINQ.
+
+## Common pitfalls
+
+> [!IMPORTANT]
+> - `Column` is abstract, but you can access all properties defined on the base type (`Name`, `DataType`, `FormatString`, `IsHidden`, `Description`, `DisplayFolder`) without casting. Only cast to a subtype when you need subtype-specific properties like `Expression` on `CalculatedColumn`.
+> - `OfType<T>()` both filters and casts. `Where(x => x is T)` only filters, leaving you with the base type. Prefer `OfType<T>()` when you need access to subtype properties.
+> - Calculated table columns are managed automatically. Edit the calculated table's `Expression` to add or change columns. You cannot add them directly.
+
+## See also
+
+- @csharp-scripts
+- @using-bpa-sample-rules-expressions
+- @how-to-navigate-tom-hierarchy
+- @how-to-tom-interfaces