Why does API test issued by apiary fail to pass request.POST processing of Django?

Question

It's the apiary's API doc

+ Request (application/json)

    {
        'name':"testUser",
        'password':"1234"

    }

When I click ”Call Resource“ on the right side,my django server get this request,but when i print(request.POST) and print(request.body) in django,it display:

<QueryDict: {}>
b'{\n    \'name\':"testUser",\n    \'password\':"1234"\n\n}'

when I use another APi test tools,django server display

<QueryDict: {'name': ['testUser'], 'password': ['1234']}>
b'name=testUser&password=1234'

Why does apiary have such a situation? What should I do so that I can use it correctly?