SymbolTableRecord.md

SymbolTableRecord Class

Overview

SymbolTableRecord is the abstract base class for all objects stored in a SymbolTable. Common examples include LayerTableRecord (Layers), BlockTableRecord (Block Definitions), LinetypeTableRecord, and TextStyleTableRecord. It defines the common properties for named table items, such as the entry name.

Namespace

Autodesk.AutoCAD.DatabaseServices

Inheritance Hierarchy

System.Object
  └─ RXObject
      └─ DBObject
          └─ SymbolTableRecord
              ├─ LayerTableRecord
              ├─ BlockTableRecord
              ├─ LinetypeTableRecord
              ├─ TextStyleTableRecord
              ├─ DimStyleTableRecord
              ├─ RegAppTableRecord
              ├─ UcsTableRecord
              ├─ ViewTableRecord
              └─ ViewportTableRecord

Key Properties

Property	Type	Description
Name	string	The name of the record (e.g., Layer name "0").
IsDependent	bool	True if the record belongs to an XRef.
IsResolved	bool	True if the XRef record is resolved.
IsRenamable	bool	True if the record can be renamed.

Key Methods

Method	Return Type	Description
GetName()	string	Gets the name safely.

Code Examples

Example 1: Creating a New Record (Generic)

// Typically you instantiate a derived class, not SymbolTableRecord directly
LayerTableRecord layer = new LayerTableRecord();
layer.Name = "MyNewLayer";
// Set other specific properties...

Example 2: Renaming a Record

using (Transaction tr = db.TransactionManager.StartTransaction())
{
    SymbolTableRecord rec = tr.GetObject(recordId, OpenMode.ForWrite) as SymbolTableRecord;
    
    if (rec.IsRenamable) // Check system protection (e.g., Layer "0")
    {
        rec.Name = "RenamedRecord";
    }
    
    tr.Commit();
}

Example 3: Checking XRef Status

public void CheckDependency(SymbolTableRecord rec)
{
    if (rec.IsDependent)
    {
        Application.DocumentManager.MdiActiveDocument.Editor.WriteMessage($"\n{rec.Name} is an XRef dependent record.");
    }
}

Example 4: Iterating a BlockTableRecord (Inherited)

// BlockTableRecord is a SymbolTableRecord, but also a container!
// Note: Only BlockTableRecord behaves as an Entity container.
// Other records (Layer, Linetype) are just definitions.

Example 5: Handling Name Validation

public void SetName(SymbolTableRecord rec, string newName)
{
    try
    {
        // SymbolTableRecord validates names (no invalid chars)
        rec.Name = newName;
    }
    catch (Exception ex)
    {
        // Handle invalid name error
        Application.DocumentManager.MdiActiveDocument.Editor.WriteMessage("\nInvalid name characters.");
    }
}

Example 6: Cloning a Record

using (Transaction tr = db.TransactionManager.StartTransaction())
{
    SymbolTableRecord original = tr.GetObject(id, OpenMode.ForRead) as SymbolTableRecord;
    SymbolTableRecord clone = original.Clone() as SymbolTableRecord;
    
    clone.Name = original.Name + "_Copy";
    
    // You would then add 'clone' to the owner table...
    tr.Commit();
}

Example 7: Using as DBObject

// Since it inherits DBObject, all DBObject methods apply
SymbolTableRecord rec = tr.GetObject(id, OpenMode.ForRead) as SymbolTableRecord;
ObjectId ownerId = rec.OwnerId; // The SymbolTable (e.g., LayerTable)

Example 8: Identifying Record Type

if (rec is LayerTableRecord) return "Layer";
if (rec is BlockTableRecord) return "Block";
if (rec is LinetypeTableRecord) return "Linetype";

Best Practices

1. Name Validation: Be aware that setting Name throws exceptions if the name contains invalid characters (<, >, /, :, etc.).
2. XRef Safety: dependent records (IsDependent == true) are generally read-only; attempting to modify them or rename them will fail.
3. Renamable Check: Always check IsRenamable before changing Name (some system records like "0" or "Defpoints" are locked).

Related Objects

• SymbolTable - The container for these records.
• LayerTable - Example table.
• LayerTableRecord - Example derived record.

References

• Autodesk SymbolTableRecord Reference