How to get models schema (type_defs) in form of string? - graphene-python

Question

Example Code
I have the following model.
class Post(Base):
__tablename__ = "post"
id = Column(Integer, primary_key=True, index=True)
title = Column(String)
author = Column(String)
content = Column(String)
time_created = Column(DateTime(timezone=True), server_default=func.now())
with this schema
class PostSchema(SQLAlchemyObjectType):
class Meta:
model = Post
Problem
How to to get the graphql schema definition in form of string like this
"""
type Post{
id: ID
title: string!
author: String!
content: String!
time_created: Int!
}
"""
I tried this, but there is not type_defs option.
graphene.Field(PostModel).type_defs

Answer 1

One option you can use is to introspect your schema not just the object type. Suppose you have a graphene schema called schema,
from graphene_sqlalchemy import SQLAlchemyObjectType
class schema(SQLAlchemyObjectType):
class Meta:
model = MyModel
you can do something like:
schema_dict = schema.introspect()
This will return a dict version of your schema and the types that you want can be found here:
types = schema_dict["__schema"]["types"]
Unfortunately, this returns a list of all object types so you might need to process it to narrow down what you want with something like:
list(filter(lambda types: types['name'] == 'PostSchema', types))
alternative way
def make_schemas(model):
d = """
"""
for i, key in model.__table__.columns.items():
x = str(key.type.python_type)
x = x.replace("<class '", '')
x = x.replace("'>", '')
x = x.title()
if x in ['Str', 'Datetime.Datetime']:
x = 'String'
if x == 'Bool':
x = 'Boolean'
d += f"""
{i}: {x}
"""
y = f"""
type {model.__tablename__.title()} {{
{d}
}}
"""
return y