From f809e76743a6ccab2badf69633bb6132c1358f2e Mon Sep 17 00:00:00 2001
From: ewinslow <ewinslow@36083f99-b078-4883-b0ff-0f9b5a30f544>
Date: Wed, 15 Sep 2010 19:31:39 +0000
Subject: 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
---
 engine/classes/Query.php | 286 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 286 insertions(+)
 create mode 100644 engine/classes/Query.php

(limited to 'engine/classes/Query.php')

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;
+	}
+
+}
+
-- 
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