pydantic v2 migrate json_loads, json_dumps

Question

Pydantic v2 has dropped json_loads (and json_dumps) config settings (see migration guide)

However, there is no indication by what replaced them. Does anyone have pointers on these?

Answer 1

In Pydantic v2 those methods have been replaced by .model_dump_json() and .model_validate_json(). See the following example:

from pydantic import BaseModel

class Model(BaseModel):
    a: str
    b: str 


m = Model(a="1", b="2")
data = m.model_dump_json()
print(type(data))

m_new = Model.model_validate_json(data)
print(type(m_new))

Which prints:

<class 'str'>
<class '__main__.Model'>

Dumping a model to a dict with json encoding instead, works like:

from pydantic import BaseModel

class Model(BaseModel):
    a: str
    b: str 


m = Model(a="1", b="2")
data = m.model_dump(mode="json")
print(type(data))

m_new = Model.model_validate(data)
print(type(m_new))

Which prints:

<class 'dict'>
<class '__main__.Model'>

I hope this helps!