Sprig_Core::update PHP Method

    public function update()
    {
        if ($this->changed()) {
            foreach ($this->_fields as $name => $field) {
                if ($field instanceof Sprig_Field_Timestamp and $field->auto_now_update) {
                    // Set the value to the current timestamp
                    $this->{$name} = time();
                }
            }
            // Check the updated data
            $data = $this->check($this->changed());
            $values = $relations = array();
            foreach ($data as $name => $value) {
                $field = $this->_fields[$name];
                if (!$field->in_db) {
                    if ($field instanceof Sprig_Field_ManyToMany) {
                        // Relationships have been changed
                        $relations[$name] = $value;
                    }
                    // Skip all fields that are not in the database
                    continue;
                }
                // Change the field name to the column name
                $values[$field->column] = $field->_database_wrap($value);
            }
            if ($values) {
                $query = DB::update($this->_table)->set($values);
                if (is_array($this->_primary_key)) {
                    foreach ($this->_primary_key as $field) {
                        $query->where($this->_fields[$field]->column, '=', $this->_fields[$field]->_database_wrap($this->_original[$field]));
                    }
                } else {
                    $query->where($this->_fields[$this->_primary_key]->column, '=', $this->_fields[$this->_primary_key]->_database_wrap($this->_original[$this->_primary_key]));
                }
                $query->execute($this->_db);
            }
            if ($relations) {
                foreach ($relations as $name => $value) {
                    $field = $this->_fields[$name];
                    $model = Sprig::factory($field->model);
                    if (isset($field->left_foreign_key) and $field->left_foreign_key) {
                        $left_fk = $field->left_foreign_key;
                    } else {
                        $left_fk = $this->fk();
                    }
                    if (isset($field->right_foreign_key) and $field->right_foreign_key) {
                        $right_fk = $field->right_foreign_key;
                    } else {
                        $right_fk = $model->fk();
                    }
                    // Find old relationships that must be deleted
                    if ($old = array_diff($this->_original[$name], $value)) {
                        // TODO this needs testing
                        $old = array_map(array($this->_fields[$this->_primary_key], '_database_wrap'), $old);
                        DB::delete($field->through)->where($left_fk, '=', $this->_fields[$this->_primary_key]->_database_wrap($this->{$this->_primary_key}))->where($right_fk, 'IN', $old)->execute($this->_db);
                    }
                    // Find new relationships that must be inserted
                    if ($new = array_diff($value, $this->_original[$name])) {
                        foreach ($new as $id) {
                            DB::insert($field->through, array($left_fk, $right_fk))->values(array($this->_fields[$this->_primary_key]->_database_wrap($this->{$this->_primary_key}), $model->field($model->pk())->_database_wrap($id)))->execute($this->_db);
                        }
                    }
                }
            }
            // Reset the original data for this record
            $this->_original = $this->as_array();
            // Everything has been updated
            $this->_changed = array();
        }
        return $this;
    }

 /**
  * Overload the update method to auto-insert
  * the timestamp for modified if not exist
  *
  * @return void
  * @author Sam de Freyssinet
  */
 public function update()
 {
     if (!isset($this->_fields['modified'])) {
         return parent::update();
     }
     if ($this->modified === NULL) {
         $this->modified = time();
     }
     return parent::update();
 }