### 甘特图
水平条形图通常用于显示项目的规划和进展，它们的根元素是 `<gantt>`.
~~~ xml
<gantt string="Ideas" date_start="invent_date" color="inventor_id">
<level object="idea.idea" link="id" domain="[]">
<field name="inventor_id"/>
</level>
</gantt>
~~~
练习
甘特图
添加一个“甘特图”允许用户查看会议调度与学术开放模块。会议应该由讲师分组。
1. 创建一个计算字段，在数小时内表示会话的持续时间
2. 添加“甘特图”视图的定义，并添加“甘特图”视图的*会议*模型的作用
*openacademy/models.py*
~~~ python
end_date = fields.Date(string="End Date", store=True,
compute='_get_end_date', inverse='_set_end_date')
hours = fields.Float(string="Duration in hours",
compute='_get_hours', inverse='_set_hours')
@api.depends('seats', 'attendee_ids')
def _taken_seats(self):
for r in self:
~~~
~~~ python
end_date = fields.Datetime.from_string(r.end_date)
r.duration = (end_date - start_date).days + 1
@api.depends('duration')
def _get_hours(self):
for r in self:
r.hours = r.duration * 24
def _set_hours(self):
for r in self:
r.duration = r.hours / 24
@api.constrains('instructor_id', 'attendee_ids')
def _check_instructor_not_in_attendees(self):
for r in self:
~~~
*openacademy/views/openacademy.xml*
~~~ xml
</field>
</record>
<record model="ir.ui.view" id="session_gantt_view">
<field name="name">session.gantt</field>
<field name="model">openacademy.session</field>
<field name="arch" type="xml">
<gantt string="Session Gantt" color="course_id"
date_start="start_date" date_delay="hours"
default_group_by='instructor_id'>
<field name="name"/>
</gantt>
</field>
</record>
<record model="ir.actions.act_window" id="session_list_action">
<field name="name">Sessions</field>
<field name="res_model">openacademy.session</field>
<field name="view_type">form</field>
<field name="view_mode">tree,form,calendar,gantt</field>
</record>
<menuitem id="session_menu" name="Sessions"
~~~