如何自省Django模型字段？

Question

当我仅知道字段名称和模型名称（均为纯字符串）时，我试图获取模型内部字段上的类信息。这怎么可能？

我可以动态加载模型：

from django.db import models
model = models.get_model('myapp','mymodel')

现在我有一个字段-‘myfield’-如何获取该字段的类？

如果字段是关系字段-如何获取相关字段？

谢谢一群！

Answer 1

您可以使用模型的_meta属性来获取字段对象，并且可以从字段中获取关系以及更多其他信息，例如，考虑一个雇员表，该雇员表具有一个部门表的外键

In [1]: from django.db import models

In [2]: model = models.get_model('timeapp', 'Employee')

In [3]: dep_field = model._meta.get_field_by_name('department')

In [4]: dep_field[0].target_field
Out[4]: 'id'

In [5]: dep_field[0].related_model
Out[5]: <class 'timesite.timeapp.models.Department'>

来自django / db / models / options.py

def get_field_by_name(self, name):
    """
    Returns the (field_object, model, direct, m2m), where field_object is
    the Field instance for the given name, model is the model containing
    this field (None for local fields), direct is True if the field exists
    on this model, and m2m is True for many-to-many relations. When
    'direct' is False, 'field_object' is the corresponding RelatedObject
    for this field (since the field doesn't have an instance associated
    with it).

    Uses a cache internally, so after the first access, this is very fast.
    """