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Diffstat (limited to 'engine/classes/Query.php')
| -rw-r--r-- | engine/classes/Query.php | 286 |
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;
+ }
+
+}
+
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