Add table class

1 files changed, 173 insertions, 0 deletions

diff --git a/app/class/table.class.php b/app/class/table.class.php
new file mode 100644
index 0000000..62f95d3
--- /dev/null
+++ b/app/class/table.class.php
@@ -0,0 +1,173 @@
+<?php
+
+/*
+ * SCROTT IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * For more information, please refer to UNLICENSE
+ */
+
+require_once "class/database.class.php";
+require_once "class/databasekeyexception.class.php";
+
+/*
+ * This class provides functionality for retrieving data from and updating
+ * data in a database table.
+ */
+abstract class table
+{
+    /*
+     * This is an array acting as a dictionary, mapping a table name (key)
+     * into another array acting as a list (value) of the fields in that
+     * table.  Classes that extend this class, should append a key=>val to
+     * this array that represents the table being modeled.  This array is
+     * used by db table IO functions to construct SQL queries.
+     */
+    protected $fields = array();
+
+    protected $db;
+
+    /*
+     * Instanciate an object representing an existing database entity
+     * named by the given GUID.  If no such GUID exists, a
+     * databasekeyexception is thrown.  If NULL is passed, no database
+     * lookups are attempted.  This is helpful for assembling new database
+     * objects.
+     */
+    public function __construct(?string $guid = NULL)
+    {
+        $this->db = database::getInstance();
+
+        if ($guid)
+            $this->loadObj($guid);
+    }
+
+    /*
+     * This function will iterate the $fields array and initialize this
+     * object's class properties based on the table=>fields mapping.  If
+     * no such GUID exists, a databasekeyexception is thrown.
+     */
+    private function loadObj(string $guid) : void
+    {
+        $guid = $this->db->esc($guid);
+
+        if (!$this->isGUID($guid))
+            throw new databasekeyexception("GUID " . $guid . " does not exist");
+
+        foreach ($this->fields as $tbl => $flds)
+        {
+            $tbl = $this->db->esc($tbl);
+            $query = "SELECT * FROM " . $tbl . " WHERE guid = '" . $guid . "'";
+            $res = $this->db->query($query)[0];
+
+            foreach ($flds as $fld)
+            {
+                if (isset($res[$fld]))
+                    $this->$fld = $res[$fld];
+            }
+        }
+    }
+
+    /*
+     * This function will update this object in the database, or insert new
+     * data if this object does not yet have a GUID.  This function uses the
+     * $fields array to construct SQL queries.
+     */
+    public function saveObj() : void
+    {
+        /* update existing object */
+        if (isset($this->guid))
+        {
+            $this->updated = $this->getCurrentTimestamp();
+
+            foreach ($this->fields as $tbl => $flds)
+            {
+                $tbl = $this->db->esc($tbl);
+                $udstr = "";
+
+                foreach ($flds as $fld)
+                {
+                    if (!isset($this->$fld))
+                        continue;
+
+                    $fld = $this->db->esc($fld);
+                    $udstr .= $fld . " = '" . $this->db->esc($this->$fld) . "', ";
+                }
+
+                if (strlen($udstr) > 0)
+                {
+                    $udstr = substr($udstr, 0, -2); // remove ", " from the end
+                    $query = "UPDATE " . $tbl . " SET " . $udstr . " WHERE guid = '" . $this->db->esc($this->guid) . "'";
+                    $this->db->query($query);
+                }
+            }
+        }
+
+        /* create new object */
+        else
+        {
+            $this->guid = $this->getNewGUID();
+            $this->created = $this->getCurrentTimestamp();
+            $this->updated = $this->created;
+
+            foreach ($this->fields as $tbl => $flds)
+            {
+                $tbl = $this->db->esc($tbl);
+                $fldstr = "";
+                $valstr = "";
+
+                foreach ($flds as $fld)
+                {
+                    if (!isset($this->$fld))
+                        continue;
+
+                    $fld = $this->db->esc($fld);
+                    $fldstr .= $fld . ", ";
+                    $valstr .= "'" . $this->db->esc($this->$fld) . "', ";
+                }
+
+                if (strlen($fldstr) > 0)
+                {
+                    $fldstr = substr($fldstr, 0, -2); // remove ", "
+                    $valstr = substr($valstr, 0, -2);
+                    $query = "INSERT INTO " . $tbl . " (" . $fldstr . ") VALUES (" . $valstr . ")";
+                    $this->db->query($query);
+                }
+            }
+        }
+    }
+
+    /*
+     * This function will remove this object from the database by deleting
+     * rows with this object's GUID from tables in $fields.  If this object
+     * does not have a GUID, throw a databasekeyexception.
+     */
+    public function delObj() : void
+    {
+        if (!isset($this->guid))
+            throw new databasekeyexception("GUID (null) does not exist");
+
+        $guid = $this->db->esc($this->guid);
+
+        foreach ($this->fields as $tbl => $flds)
+        {
+            $tbl = $this->db->esc($tbl);
+            $query = "DELETE FROM " . $tbl . " WHERE guid = '" . $guid . "'";
+            $this->db->query($query);
+        }
+
+        /* garbage collection */
+        $query = "DELETE FROM members WHERE guid = '" . $guid . "' OR member = '" . $guid . "'";
+        $this->db->query($query);
+
+        $query = "DELETE FROM views WHERE guid = '" . $guid . "' OR viewer = '" . $guid . "'";
+        $this->db->query($query);
+    }
+}
+
+?>