API CHANGE: Add SQLQuery::clearSelect(), SQLQuery::selectField() and SQLQuery::itemisedSelect() to make it easier for other subsystems to use SQLQuery without resorting to direct property access.

API CHANGE: Remove DataQuery::select() in place of DataQuery::selectField().
BUGFIX: Remove direct property access to SQLQuery::$select

forms/ManyManyComplexTableField.php

@@ -77,7 +77,7 @@ class ManyManyComplexTableField extends HasManyComplexTableField {
 		
 	function getQuery() {
 		$query = parent::getQuery();
-		$query->select[] = "CASE WHEN \"{$this->manyManyParentClass}ID\" IS NULL THEN '0' ELSE '1' END AS \"Checked\"";
+		$query->selectField("CASE WHEN \"{$this->manyManyParentClass}ID\" IS NULL THEN '0' ELSE '1' END", "Checked");
 		$query->groupby[] = "\"{$this->manyManyParentClass}ID\""; // necessary for Postgres
 
 		return $query;

model/Aggregate.php

@@ -78,7 +78,7 @@ class Aggregate extends ViewableData {
 	protected function query($attr) {
 		$singleton = singleton($this->type);
 		$query = $singleton->buildSQL($this->filter);
-		$query->select = array($attr);
+		$query->select($attr);
 		$query->orderby = null;
 		$singleton->extend('augmentSQL', $query);
 		return $query;
@@ -161,7 +161,7 @@ class Aggregate_Relationship extends Aggregate {
 			$query = $this->object->getManyManyComponentsQuery($this->relationship, $this->filter);
 		}
 		
-		$query->select = array($attr);
+		$query->select($attr);
 		$query->groupby = array();
 		
 		$singleton = singleton($this->type);

model/DataQuery.php

@@ -205,8 +205,7 @@ class DataQuery {
 						user_error("Bad collision item '$collision'", E_USER_WARNING);
 					}
 				}
-				$query->select[$k] = "CASE " . implode( " ", $caseClauses) . " ELSE NULL END"
+				$query->selectField("CASE " . implode( " ", $caseClauses) . " ELSE NULL END", $k);
-					.  " AS \"$k\"";
 			}
 		}
 
@@ -221,8 +220,8 @@ class DataQuery {
 			}
 		}
 
-		$query->select[] = "\"$baseClass\".\"ID\"";
+		$query->selectField("\"$baseClass\".\"ID\"", "ID");
-		$query->select[] = "CASE WHEN \"$baseClass\".\"ClassName\" IS NOT NULL THEN \"$baseClass\".\"ClassName\" ELSE '$baseClass' END AS \"RecordClassName\"";
+		$query->selectField("CASE WHEN \"$baseClass\".\"ClassName\" IS NOT NULL THEN \"$baseClass\".\"ClassName\" ELSE '$baseClass' END", "RecordClassName");
 
 		// TODO: Versioned, Translatable, SiteTreeSubsites, etc, could probably be better implemented as subclasses of DataQuery
 		singleton($this->dataClass)->extend('augmentSQL', $query, $this);
@@ -274,14 +273,18 @@ class DataQuery {
 						$qualCol = "\"$parts[0]\"";
 					}
 					
+					// To-do: Remove this if block once SQLQuery::$select has been refactored to store itemisedSelect()
+					// format internally; then this check can be part of selectField()
 					if(!isset($query->select[$col]) && !in_array($qualCol, $query->select)) {
-						$query->select[] = $qualCol;
+						$query->selectField($qualCol);
 					}
 				} else {
 					$qualCol = '"' . implode('"."', $parts) . '"';
 					
+					// To-do: Remove this if block once SQLQuery::$select has been refactored to store itemisedSelect()
+					// format internally; then this check can be part of selectField()
 					if(!in_array($qualCol, $query->select)) {
-						$query->select[] = $qualCol;
+						$query->selectField($qualCol);
 					}
 				}
 			}
@@ -367,12 +370,12 @@ class DataQuery {
 		if($databaseFields) foreach($databaseFields as $k => $v) {
 			if((is_null($columns) || in_array($k, $columns)) && !isset($compositeFields[$k])) {
 				// Update $collidingFields if necessary
-				if(isset($query->select[$k])) {
+				if($expressionForField = $query->expressionForField($k)) {
-					if(!isset($this->collidingFields[$k])) $this->collidingFields[$k] = array($query->select[$k]);
+					if(!isset($this->collidingFields[$k])) $this->collidingFields[$k] = array($expressionForField);
 					$this->collidingFields[$k][] = "\"$tableClass\".\"$k\"";
 				
 				} else {
-					$query->select[$k] = "\"$tableClass\".\"$k\"";
+					$query->selectField("\"$tableClass\".\"$k\"", $k);
 				}
 			}
 		}
@@ -596,8 +599,12 @@ class DataQuery {
 	 */
 	public function subtract(DataQuery $subtractQuery, $field='ID') {
 		$subSelect= $subtractQuery->getFinalisedQuery();
-		$subSelect->select($this->expressionForField($field, $subSelect));
+		$fieldExpression = $this->expressionForField($field, $subSelect);
+		$subSelect->clearSelect();
+		$subSelect->selectField($fieldExpression);
 		$this->where($this->expressionForField($field, $this).' NOT IN ('.$subSelect->sql().')');
+
+		return $this;
 	}
 
 	/**
@@ -607,7 +614,9 @@ class DataQuery {
 		$fieldExpressions = array_map(create_function('$item', 
 			"return '\"$table\".\"' . \$item . '\"';"), $fields);
 		
-		$this->select($fieldExpressions);
+		$this->query->select($fieldExpressions);
+
+		return $this;
 	}
 
 	/**
@@ -636,7 +645,7 @@ class DataQuery {
 	 * Clear the selected fields to start over
 	 */
 	public function clearSelect() {
-		$this->query->select = array();
+		$this->query->clearSelect();
 
 		return $this;
 	}
@@ -644,8 +653,8 @@ class DataQuery {
 	/**
 	 * Select the given field expressions.  You must do your own escaping
 	 */
-	protected function select($fieldExpressions) {
+	protected function selectField($fieldExpression, $alias = null) {
-		$this->query->select = array_merge($this->query->select, $fieldExpressions);
+		$this->query->selectField($fieldExpression, $alias);
 	}
 
 	//// QUERY PARAMS

model/ManyManyList.php

@@ -133,7 +133,7 @@ class ManyManyList extends RelationList {
     function removeAll() {
 		$query = $this->dataQuery()->query();
 		$query->delete = true;
-		$query->select = array('*');
+		$query->select(array('*'));
 		$query->from = array("\"$this->joinTable\"");
 		$query->orderby = null;
 		$query->execute();

model/SQLQuery.php

@@ -113,6 +113,14 @@ class SQLQuery {
 		$this->limit($limit);
 	}
 	
+	/**
+	 * Clear the selected fields to start over
+	 */
+	function clearSelect() {
+		$this->select = array();
+		return $this;
+	}
+	
 	/**
 	 * Specify the list of columns to be selected by the query.
 	 *
@@ -153,9 +161,26 @@ class SQLQuery {
 			$this->select[] = $fields;
 		}
 	}
+	
+	/**
+	 * Select an additional field
+	 *
+	 * @param $field The field to select
+	 * @param $alias The alias of that field
+	 */
+	public function selectField($field, $alias = null) {
+		// Let's not put unnecessary aliases into the query
+		if($alias && preg_match('/"' . preg_quote($alias) . '"$/', $field)) {
+			$alias = null;
+		}
+		
+		if($alias) $this->select[] = "$field AS \"$alias\"";
+		else $this->select[] = $field;
+	}
 
 	/**
-	 * Return the SQL expression for the given field
+	 * Return the SQL expression for the given field alias.
+	 * Returns null if the given alias doesn't exist.
 	 *
 	 * @todo This should be refactored after $this->select is changed to make that easier
 	 */
@@ -166,6 +191,7 @@ class SQLQuery {
 			else if(preg_match('/"?([^"]*)"?/', $sel, $matches)) $selField = $matches[2];
 			if($selField == $field) return $sel;
 		}
+		return null;
 	}
 	
 	/**
@@ -542,6 +568,29 @@ class SQLQuery {
 		Deprecation::notice('3.0', 'Please use prepareWhere() instead of getFilter()');
 		return $this->prepareWhere();
 	}
+	
+	/**
+	 * Return an itemised select list as a map, where keys are the aliases, and values are the column sources.
+	 * Aliases will always be provided (if the alias is implicit, the alias value will be inferred), and won't be quoted.
+	 * E.g., 'Title' => '"SiteTree"."Title"'.
+	 */
+	public function itemisedSelect() {
+		$output = array();
+		foreach($this->select as $item) {
+			$split = preg_split('/ AS /i', $item, 2);
+			if(isset($split[1])) {
+				$source = $split[0];
+				$alias = $split[1];
+			} else {
+				$source = $item;
+				$alias = substr($item,strrpos($item,'.')+1);
+			}
+			// Drop quoting
+			$alias = preg_replace('/^"(.*)"$/','\\1', $alias);
+			$output[$alias] = $source;
+		}
+		return $output;
+	}
 
 	/**
 	 * Returns the WHERE clauses ready for inserting into a query.

model/Versioned.php

@@ -149,9 +149,9 @@ class Versioned extends DataExtension {
 				
 				// Add all <basetable>_versions columns
 				foreach(self::$db_for_versions_table as $name => $type) {
-					$query->select[] = sprintf('"%s_versions"."%s"', $baseTable, $name);
+					$query->selectField(sprintf('"%s_versions"."%s"', $baseTable, $name), $name);
 				}
-				$query->select[] = sprintf('"%s_versions"."%s" AS "ID"', $baseTable, 'RecordID');
+				$query->selectField(sprintf('"%s_versions"."%s"', $baseTable, 'RecordID'), "ID");
 
 				if($table != $baseTable) {
 					$query->from[$table] .= " AND \"{$table}_versions\".\"Version\" = \"{$baseTable}_versions\".\"Version\"";
@@ -195,9 +195,9 @@ class Versioned extends DataExtension {
 		
     		// Add all <basetable>_versions columns
     		foreach(self::$db_for_versions_table as $name => $type) {
-    			$query->selectMore(sprintf('"%s_versions"."%s"', $baseTable, $name));
+    			$query->selectField(sprintf('"%s_versions"."%s"', $baseTable, $name), $name);
     		}
-    		$query->selectMore(sprintf('"%s_versions"."%s" AS "ID"', $baseTable, 'RecordID'));
+    		$query->selectField(sprintf('"%s_versions"."%s"', $baseTable, 'RecordID'), "ID");
     		
     		// latest_version has one more step
     	    // Return latest version instances, regardless of whether they are on a particular stage
@@ -722,7 +722,7 @@ class Versioned extends DataExtension {
 		
 		// Add all <basetable>_versions columns
 		foreach(self::$db_for_versions_table as $name => $type) {
-			$query->select[] = sprintf('"%s_versions"."%s"', $baseTable, $name);
+			$query->selectField(sprintf('"%s_versions"."%s"', $baseTable, $name), $name);
 		}
 		
 		$query->where[] = "\"{$baseTable}_versions\".\"RecordID\" = '{$this->owner->ID}'";

model/fieldtypes/Money.php

@@ -96,8 +96,8 @@ class Money extends DBField implements CompositeDBField {
 	
 	function addToQuery(&$query) {
 		parent::addToQuery($query);
-		$query->select[] = sprintf('"%sAmount"', $this->name);
+		$query->selectField(sprintf('"%sAmount"', $this->name));
-		$query->select[] = sprintf('"%sCurrency"', $this->name);
+		$query->selectField(sprintf('"%sCurrency"', $this->name));
 	}
 
 	function setValue($value, $record = null, $markChanged = true) {

tests/model/SQLQueryTest.php

@@ -23,14 +23,14 @@ class SQLQueryTest extends SapphireTest {
 	
 	function testSelectFromUserSpecifiedFields() {
 		$query = new SQLQuery();
-		$query->select = array("Name", "Title", "Description");
+		$query->select(array("Name", "Title", "Description"));
 		$query->from[] = "MyTable";
 		$this->assertEquals("SELECT Name, Title, Description FROM MyTable", $query->sql());
 	}
 	
 	function testSelectWithWhereClauseFilter() {
 		$query = new SQLQuery();
-		$query->select = array("Name","Meta");
+		$query->select(array("Name","Meta"));
 		$query->from[] = "MyTable";
 		$query->where[] = "Name = 'Name'";
 		$query->where[] = "Meta = 'Test'";