烧瓶应用程序中更智能的 sqlalchemy wtf 动态过滤器

Question

我有一个过滤表的表单，我希望表单条目构建一个 sqlalchemy 语句。

因为我有“无过滤器”选项，所以我不能只让表单域进入过滤器（“此处的表单域”）。但是必须有比做每一个排列更好的方法

AT= list(set([h.assigned for h in models.Request.query.all()]))
AT.append('No Filter')
form.assigned.choices=zip(AT,AT)
requestlist= models.Request.query.all() 
if form.validate_on_submit():

    if form.status.data=='No Filter' and form.assigned.data=='No Filter' and form.requestor.data=='No Filter':
            requestlist= models.Request.query.all() 
    elif form.status.data != 'No Filter' and form.assigned.data=='No Filter' and form.requestor.data=='No Filter':
        requestlist = db.session.query(models.Request).filter(models.Request.status.like(form.status.data)).all()
    elif form.status.data == 'No Filter' and form.assigned.data!='No Filter' and form.requestor.data=='No Filter':
        requestlist = db.session.query(models.Request).filter(models.Request.assigned.like(form.assigned.data)).all()
    elif form.status.data == 'No Filter' and form.assigned.data=='No Filter' and form.requestor.data!='No Filter':
        requestlist = db.session.query(models.Request).filter(models.Request.requestedBy.like(form.requestor.data)).all()
    elif form.status.data != 'No Filter' and form.assigned.data=='No Filter' and form.requestor.data!='No Filter':
        requestlist = db.session.query(models.Request).filter(models.Request.requestedBy.like(form.requestor.data))\
        .filter(models.Request.status.like(form.status.data)).all()
    elif form.status.data == 'No Filter' and form.assigned.data !='No Filter' and form.requestor.data!='No Filter':
        requestlist = db.session.query(models.Request).filter(models.Request.requestedBy.like(form.requestor.data))\
        .filter(models.Request.assigned.like(form.assigned.data)).all()
    elif form.status.data != 'No Filter' and form.assigned.data !='No Filter' and form.requestor.data =='No Filter':
        requestlist = db.session.query(models.Request).filter(models.Request.status.like(form.status.data))\
        .filter(models.Request.assigned.like(form.assigned.data)).all()
    elif form.status.data != 'No Filter' and form.assigned.data !='No Filter' and form.requestor.data !='No Filter':
        requestlist = db.session.query(models.Request).filter(models.Request.status.like(form.status.data))\
        .filter(models.Request.requestedBy.like(form.requestor.data))\
        .filter(models.Request.assigned.like(form.assigned.data)).all()

Answer 1

您可以一个接一个地添加多个filter(...)子句：

if form.validate_on_submit():
    requestlist = models.Request.query

    if form.status.data != 'No Filter':
        requestlist = requestlist.filter(models.Request.status.like(form.status.data))

    if form.assigned.data != 'No Filter':
        requestlist = requestlist.filter(models.Request.assigned.like(form.assigned.data))

    if form.requestor.data != 'No Filter':
        requestlist = requestlist.filter(models.Request.requestedBy.like(form.requestor.data))

    return requestlist.all()

或者更一般地说，您可能可以执行以下操作：

field_names = ['status', 'assigned', 'requestor']
if form.validate_on_submit():
    requestlist = models.Request.query

    for field in field_names:
        f_value = getattr(form, field).data
        if f_value != 'No Filter':
            requestlist = requestlist.filter(getattr(models.Request, field).like(f_value))

    return requestlist.all()

我看到的唯一问题是，有时表单上的名称和模型上的名称不匹配。一个例子是requestedBy 和requestor。在这种情况下，您可能会在 field_names 中定义字典而不是列表。