Refs #2220: Pulled remaining classes out of lib files. Core classes now autoloaded via __autoload().

git-svn-id: http://code.elgg.org/elgg/trunk@6941 36083f99-b078-4883-b0ff-0f9b5a30f544

1 files changed, 286 insertions, 0 deletions

diff --git a/engine/classes/Query.php b/engine/classes/Query.php
new file mode 100644
index 000000000..ebc7e1474
--- /dev/null
+++ b/engine/classes/Query.php
@@ -0,0 +1,286 @@
+<?php

+/**

+ * @class Query Provides a framework to construct complex queries in a safer environment.

+ *

+ * The usage of this class depends on the type of query you are executing, but the basic idea is to

+ * construct a query out of pluggable classes.

+ *

+ * Once constructed SQL can be generated using the toString method, this should happen automatically

+ * if you pass the Query object to get_data or similar.

+ *

+ * To construct a query, create a new Query() object and begin populating it with the various classes

+ * that define the various aspects of the query.

+ *

+ * Notes:

+ * 	- You do not have to specify things in any particular order, provided you specify all required

+ * 	  components.

+ *  - With database tables you do not have to specify your db prefix, this will be added automatically.

+ *  - When constructing your query keep an eye on the error log - any problems will get spit out here.

+ * 	  Note also that __toString won't let you throw Exceptions (!!!) so these are caught and echoed to

+ *    the log instead.

+ *

+ * Here is an example of a select query which requests some data out of the entities table with an

+ * order and limit that uses a subset where and some normal where queries:

+ *

+ * <blockquote>

+ * 		// Construct the query

+ * 		$query = new Query();

+ *

+ * 		// Say which table we're interested in

+ * 		$query->addTable(new TableQueryComponent("entities"));

+ *

+ * 		// What fields are we interested in

+ * 		$query->addSelectField(new SelectFieldQueryComponent("entities","*"));

+ *

+ * 		// Add access control (Default access control uses default fields on entities table.

+ * 		// Note that it will error without something specified here!

+ * 		$query->setAccessControl(new AccessControlQueryComponent());

+ *

+ * 		// Set a limit and offset, may be omitted.

+ * 		$query->setLimitAndOffset(new LimitOffsetQueryComponent(10,0));

+ *

+ * 		// Specify the order, may be omitted

+ * 		$query->setOrder(new OrderQueryComponent("entities", "subtype", "desc"));

+ *

+ * 		// Construct a where query

+ * 		//

+ * 		// This demonstrates a WhereSet which lets you have sub wheres, a

+ * 		// WhereStatic which lets you compare a table field against a value and a

+ * 		// Where which lets you compare a table/field with another table/field.

+ * 		$query->addWhere(

+ * 			new WhereSetQueryComponent(

+ * 				array(

+ * 					new WhereStaticQueryComponent("entities", "subtype","=", 1),

+ * 					new WhereQueryComponent("entities","subtype","=", "entities", "subtype")

+ * 				)

+ * 			)

+ * 		);

+ *

+ * 		get_data($query);

+ * </blockquote>

+ *

+ * @author Curverider Ltd

+ */

+class Query

+{

+

+	/// The limit of the query

+	private $limit_and_offset;

+

+	/// Fields to return on a query

+	private $fields;

+

+	/// Tables to use in a from query

+	private $tables;

+

+	/// Join tables

+	private $joins;

+

+	/// Set values

+	private $sets;

+

+	/// Where query

+	private $where;

+

+	/// Order by

+	private $order;

+

+	/// The query type

+	private $query_type;

+

+	/// ACL

+	private $access_control;

+

+	/**

+	 * Construct query & initialise variables

+	 */

+	function __construct()

+	{

+		$this->fields = array();

+		$this->tables = array();

+		$this->joins = array();

+		$this->where = array();

+		$this->sets = array();

+

+		$this->setQueryType(new SelectQueryTypeQueryComponent());

+	}

+

+	/**

+	 * Add limits and offsets to the query.

+	 *

+	 * @param LimitOffsetQueryComponent $component The limit and offset.

+	 */

+	public function setLimitAndOffset(LimitOffsetQueryComponent $component) { $this->limit_and_offset = $component; }

+

+	/**

+	 * Reset and set the field to the select statement.

+	 *

+	 * @param SelectFieldQueryComponent $component Table and field component.

+	 */

+	public function setSelectField(SelectFieldQueryComponent $component)

+	{

+		$this->fields = array();

+		return $this->addSelectField($component);

+	}

+

+	/**

+	 * Add a select field.

+	 *

+	 * @param SelectFieldQueryComponent $component Add a component.

+	 */

+	public function addSelectField(SelectFieldQueryComponent $component) { $this->fields[] = $component; }

+

+	/**

+	 * Add a join to the component.

+	 *

+	 * @param JoinQueryComponent $component The join.

+	 */

+	public function addJoin(JoinQueryComponent $component) { $this->joins[] = $component; }

+

+	/**

+	 * Set a field value in an update or insert statement.

+	 *

+	 * @param SetQueryComponent $component Fields to set.

+	 */

+	public function addSet(SetQueryComponent $component) { $this->sets[] = $component; }

+

+	/**

+	 * Set the query type, i.e. "select", "update", "insert" & "delete".

+	 *

+	 * @param QueryTypeQueryComponent $component The query type.

+	 */

+	public function setQueryType(QueryTypeQueryComponent $component) { $this->query_type = $component; }

+

+	/**

+	 * Attach an order component.

+	 *

+	 * @param OrderQueryComponent $component The order component.

+	 */

+	public function setOrder(OrderQueryComponent $component) { $this->order = $component; }

+

+	/**

+	 * Add a table to the query.

+	 *

+	 * @param TableQueryComponent $component Table to add.

+	 */

+	public function addTable(TableQueryComponent $component) { $this->tables[] = $component; }

+

+	/**

+	 * Add a where clause to the query.

+	 *

+	 * @param WhereQueryComponent $component The where component

+	 */

+	public function addWhere(WhereQueryComponent $component) { $this->where[] = $component; }

+

+	/**

+	 * Set access control.

+	 *

+	 * @param AccessControlQueryComponent $component Access control.

+	 */

+	public function setAccessControl(AccessControlQueryComponent $component) { $this->access_control = $component; }

+

+	public function __toString()

+	{

+		global $CONFIG;

+

+		$sql = "";

+

+		try

+		{

+			// Query prefix & fields

+			if (!empty($this->query_type))

+			{

+				$sql .= "{$this->query_type} ";

+

+				if (!empty($this->fields))

+				{

+					$fields = "";

+

+					foreach ($this->fields as $field)

+						$fields .= "$field";

+

+					$sql .= " $fields from ";

+				}

+				else

+					throw new DatabaseException(elgg_echo('DatabaseException:SelectFieldsMissing'));

+			}

+			else

+				throw new DatabaseException(elgg_echo('DatabaseException:UnspecifiedQueryType'));

+

+			// Tables

+			if (!empty($this->tables))

+			{

+				foreach($this->tables as $table)

+					$sql .= "$table, ";

+

+				$sql = trim($sql, ", ");

+			}

+			else

+				throw new DatabaseException(elgg_echo('DatabaseException:NoTablesSpecified'));

+

+			// Joins on select queries

+			if ($this->query_type->query_type == 'select')

+			{

+				if (!empty($this->joins))

+				{

+					foreach($this->joins as $join)

+						$sql .= "$join ";

+				}

+			}

+

+			// Setting values

+			if (

+				($this->query_type->query_type == 'update') ||

+				($this->query_type->query_type == 'insert')

+			)

+			{

+				$sql .= "set ";

+

+				foreach ($this->sets as $set)

+					$sql .= "$set, ";

+

+				$sql = trim($sql, ", ") . " ";

+			}

+

+			// Where

+			if (!empty($this->where))

+			{

+				$sql .= " where 1 ";

+

+				foreach ($this->where as $where)

+					$sql .= "$where ";

+			}

+

+			// Access control

+			if (!empty($this->access_control))

+			{

+

+				// Catch missing Where

+				if (empty($this->where))

+					$sql .= " where 1 ";

+

+				$sql .= "{$this->access_control} ";

+			}

+			else

+				throw new DatabaseException(elgg_echo('DatabaseException:NoACL'));

+

+			// Order by

+			if (!empty($this->order))

+				$sql .= "{$this->order} ";

+

+			// Limits

+			if (!empty($this->limit_and_offset))

+				$sql .= "{$this->limit_and_offset} ";

+

+

+

+		} catch (Exception $e) {

+			trigger_error($e, E_USER_WARNING);

+		}

+

+

+		return $sql;

+	}

+

+}

+