基于文本长度的django过滤器 [英] django filter on the basis of text length

问题描述

我想根据文本的长度过滤我的模型
像

I would like to filter my model on the basis of the length of the text Something like

MyModel.objects.filter(len(text) > 10)

其中text是Char或Text字段在MyModel模型中

where text is a Char or Text field in MyModel model

提前感谢

推荐答案

如果您只是添加一个预先计算（记住）文本长度
的列，那么更好的和更快。

It would be much better and faster if you just add a column that pre-calculates(memoizes) the length of the text.

eg

class MyModel(models.Model):
    text = models.TextField()
    text_len = models.PositiveIntegerField()

     def save(self, *args, **kwargs):
         self.text_len = len(self.text)
         return super(MyModel, self).save(*args, **kwargs)

MyModel.objects.filter(text_len__gt = 10)     # Here text_len is pre-calculated by us on `save`

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