add column unique numbering scheme, more efficient selects

app/Tables/Column.php

@@ -11,9 +11,10 @@ use MightyPork\Utils\Utils;
 /**
  * Helper class representing one column in a data table.
  *
+ * @property-read string $id
+ * @property-read string $type
  * @property-read string $name
  * @property-read string $title
- * @property-read string $type
  */
 class Column implements JsonSerializable
 {
@@ -21,9 +22,10 @@ class Column implements JsonSerializable
         'int', 'bool', 'float', 'string'
     ];
 
+    private $id;
+    private $type;
     private $name;
     private $title;
-    private $type;
 
     public static function columnsFromJson($columns)
     {
@@ -36,13 +38,13 @@ class Column implements JsonSerializable
         }, $columns);
     }
 
-    public function __get($name)
+    /**
+     * Set column ID
+     * @param string $id - GCID
+     */
+    public function setID($id)
     {
-        if (property_exists($this, $name)) {
-            return $this->$name;
-        }
-
-        throw new NotApplicableException("No such column property");
+        $this->id = $id;
     }
 
     /**
@@ -52,18 +54,32 @@ class Column implements JsonSerializable
      */
     public function __construct($obj)
     {
-        $b = new \objBag($obj);
+        $b = objBag($obj);
+
+        if (!$b->has('name')) throw new NotApplicableException('Missing name in column');
+        if (!$b->has('type')) throw new NotApplicableException('Missing type in column');
+
+        if ($b->name[0] == '_') { // global row ID
+            throw new NotApplicableException("Column name can't start with underscore.");
+        }
+
+        if (!in_array($b->type, self::colTypes)) {
+            throw new NotApplicableException("\"$b->type\" is not a valid column type.");
+        }
+
+        $this->id = $b->get('id', null);
         $this->name = $b->name;
-        $this->title = $b->title;
         $this->type = $b->type;
+        $this->title = $b->title ?: $b->name;
+    }
 
-        if ($this->name == '_grid') { // global row ID
-            throw new NotApplicableException("_grid is a reserved column name.");
+    public function __get($name)
+    {
+        if (property_exists($this, $name)) {
+            return $this->$name;
         }
 
-        if (!in_array($this->type, self::colTypes)) {
-            throw new NotApplicableException("\"$this->type\" is not a valid column type.");
-        }
+        throw new NotApplicableException("No such column property: $name");
     }
 
     /**
@@ -72,6 +88,7 @@ class Column implements JsonSerializable
     public function toArray()
     {
         return [
+            'id' => $this->id,
             'name' => $this->name,
             'title' => $this->title,
             'type' => $this->type,