今天我滴户外网站开发进度走到了多条件搜索活动的界面，不难但是涉及的细节很多，所以简单记录下
先上实现截图：

搜索功能实现效果图

具体实现一步步走起~

创建Form以及Form的布局显示

这个搜索框也可以直接抛弃Form....
表单类创建了需要的field并赋值

class ActivitySearchForm(Form):
    keyword = StringField('搜索关键字')
    outdoor = RadioField('活动类型')
    days = RadioField('出行天数')
    sort = RadioField('排序方式')
    submit = SubmitField('搜索活动')

    def __init__(self, *args, **kwargs):
        super(ActivitySearchForm, self).__init__(*args, **kwargs)
        #为单选钮赋默认值
        self.outdoor.choices = [(item.id, item.name) for item in OutdoorType.show_list()]
        days_source = [(1, '1天'), (3, '2-3天'), (7, '4-7天'), (15, '8-15天'), (16, '16天以上')]
        self.days.choices = days_source
        sort_source = [(0, '最新发布'), (1, '最多访问'), (2, '价格由低到高'), (3, '价格由高到低')]
        self.sort.choices = sort_source

界面选择表格布局，代码：

<form action="" method="post" class="form-horizontal" role="form">
    {{ form.hidden_tag() }}
    <table class="table vertical-center">
      <tbody>
        <tr class="active">
          <td class="highlight">搜索关键字</td>
          <td><div class="col-sm-6">
                    {{ form.keyword(class_='form-control') }}
                </div>
                <div class="col-sm-2">
                    {{ form.submit(class_='btn btn-warning') }}
                </div>
          </td>
        </tr>
        <tr class="warning">
          <td class="highlight">活动类型</td>
          <td>{{ form.outdoor(class_='radio-list-inline') }}</td>
        </tr>
        <tr class="active">
          <td class="highlight">出行天数</td>
          <td>{{ form.days(class_='radio-list-inline') }}</td>
        </tr>
        <tr class="warning">
          <td class="highlight">排序类型</td>
          <td>{{ form.sort(class_='radio-list-inline') }}</td>
        </tr>
      </tbody>
    </table>
    </form>

在活动类'Activity`中添加一个根据筛选项取得活动的方法

这里就是不停迭代filter_by和order_by
这里有一点需要注意，搜索框里面的几个单选钮，如果没有选择都返回'None'，是None这个字符串，而部署None类型，所以判断的时候用的都是!= 'None'
这个还值得注意的是用空白分隔的关键字做搜索的实现
最后把query构建好了，用paginate分页取回活动

@staticmethod
    def get_activities_search(keyword, outdoor, days, sort, page=1):
        activities = Activity.query
        if outdoor != 'None': #户外类型
            t = OutdoorType.query.get(int(outdoor))
            activities = t.activities
        if keyword:#允许多个空格分隔的搜索关键字
            keywords = keyword.split()
            for k in keywords:
                activities = activities.filter(Activity.name.like('%'+k+'%'))
        if days != 'None': #出行天数
            if days == '1':
                activities = activities.filter(Activity.days == 1)
            elif days == '3':
                activities = activities.filter(or_(Activity.days == 2, Activity.days == 3))
            elif days == '7':
                activities = activities.filter(and_(Activity.days > 3, Activity.days < 8))
            elif days == '15':
                activities = activities.filter(and_(Activity.days > 7, Activity.days < 16))
            else:
                activities = activities.filter(Activity.days > 15)
        if sort != 'None':#排序
            if sort == '1':
                activities = activities.order_by(Activity.view_count.desc())
            elif sort == '2':
                activities = activities.order_by(Activity.price.asc())
            elif sort == '3':
                activities = activities.order_by(Activity.price.desc())
            else:
                activities = activities.order_by(Activity.timestamp.desc())
        return activities.paginate(page, current_app.config['PAGECOUNT_ACTIVITY'], error_out=False)

在View里面添加处理逻辑

在分页浏览中使用session保存搜索条件，每次POST修改搜索条件的时候，记得把page设成1

@team.route('/activites/search', methods=['GET', 'POST'])
def activities_search():
    form = ActivitySearchForm()
    page = request.args.get('page', 1, type=int)
    if request.method == 'POST':
        #每次POST，添加查询字符串，取回第一页
        session['activity-keyword'] = form.keyword.data
        session['activity-outdoor'] = form.outdoor.data
        session['activity-days'] = form.days.data
        session['activity-sort'] = form.sort.data
        page = 1
    pagination = Activity.get_activities_search(
        session.get('activity-keyword', ""),
        session.get('activity-outdoor', 'None'),
        session.get('activity-days', 'None'),
        session.get('activity-sort', 'None'),
        page
    )
    activities = pagination.items
    return render_template('activities_search.html',
                           form=form,
                           activities = activities,
                           pagination = pagination)

这里需要特别注意的是，因为使用了session，所以在从别的页面直接跳转到搜索页时，显示的是session搜索条件下的活动，所以在跳转前要将session清空