Flask应用程序中更智能的sqlalchemy wtf动态过滤器

debugcn 发表于 Dev

切特·梅恩泽（Chet Meinzer）

我有一个过滤表的表单，并且我希望表单条目构建一个sqlalchemy语句。

因为我有“无过滤器”选项，所以我不能仅将表单字段放入过滤器（“此处的表单字段”）。但是必须有比进行像这样的每个排列更好的方法

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()

从

您可以filter(...)一个接一个地添加多个子句：

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()

或更笼统地说，您可以执行以下操作：

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，有时表单和模型上的名称不匹配。一个示例是requestedBy和requestor。在这种情况下，您可以定义字典而不是中的列表field_names。

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