Update a record via a GraphQL API using Graphene and SQLAlchemy

Question

I am building a GraphQL API using the python packages Flask, SQLAlchemy, Graphene and Graphene-SQLAlchemy. I have followed the SQLAlchemy + Flask Tutorial. I am able to execute queries and mutations to create records. Now I would like to know what is the best way to update an existing record.

Here is my current script schema.py:

from graphene_sqlalchemy import SQLAlchemyObjectType
from database.batch import BatchOwner as BatchOwnerModel
import api_utils  # Custom methods to create records in database
import graphene


class BatchOwner(SQLAlchemyObjectType):
    """Batch owners."""
    class Meta:
        model = BatchOwnerModel
        interfaces = (graphene.relay.Node,)


class CreateBatchOwner(graphene.Mutation):
    """Create batch owner."""
    class Arguments:
        name = graphene.String()

    # Class attributes
    ok = graphene.Boolean()
    batch_owner = graphene.Field(lambda: BatchOwner)

    def mutate(self, info, name):
        record = {'name': name}
        api_utils.create('BatchOwner', record) # Custom methods to create records in database
        batch_owner = BatchOwner(name=name)
        ok = True
        return CreateBatchOwner(batch_owner=batch_owner, ok=ok)


class Query(graphene.ObjectType):
    """Query endpoint for GraphQL API."""
    node = graphene.relay.Node.Field()
    batch_owner = graphene.relay.Node.Field(BatchOwner)
    batch_owners = SQLAlchemyConnectionField(BatchOwner)


class Mutation(graphene.ObjectType):
    """Mutation endpoint for GraphQL API."""
    create_batch_owner = CreateBatchOwner.Field()


schema = graphene.Schema(query=Query, mutation=Mutation)

Remarks:

My object BatchOwner has only 2 attributes (Id, name)
To be able to update the BatchOwner name, I assume I need to provide the database Id (not the relay global Id) as an input argument of some update method
But when I query for a BatchOwner from my client, Graphene only returns me the global Id which is base64 encoded (example: QmF0Y2hPd25lcjox, which correspond to BatchOwner:1)

Example of response:

{
    "data": {
        "batchOwners": {
            "edges": [
                {
                    "node": {
                        "id": "QmF0Y2hPd25lcjox",
                        "name": "Alexis"
                    }
                }
            ]
        }
    }
}

The solution I am thinking of at the moment would be:

Create an update mutation which takes the global Id as an argument
Decode the global Id (how?)
Use the database Id retrieved from the decoded global Id to query on the database and update the corresponding record

Is there a better way to do this?

Alexis.Rolland Alexis.Rolland · Accepted Answer · 2018-01-20T17:15:57

I have found a solution using the method from_global_id (documented here)

from graphql_relay.node.node import from_global_id

I added the following class to schema.py:

class UpdateBatchOwner(graphene.Mutation):
    """Update batch owner."""
    class Arguments:
        id = graphene.String()
        name = graphene.String()

    # Class attributes
    ok = graphene.Boolean()
    batch_owner = graphene.Field(lambda: BatchOwner)

    def mutate(self, info, id, name):
        id = from_global_id(id)
        record = {'id': id[1], 'name': name}
        api_utils.update('BatchOwner', record)
        batch_owner = BatchOwner(id=id, name=name)
        ok = True
        return UpdateBatchOwner(batch_owner=batch_owner, ok=ok)

And I updated the Mutation class:

class Mutation(graphene.ObjectType):
    """Mutation endpoint for GraphQL API."""
    create_batch_owner = CreateBatchOwner.Field()
    update_batch_owner = UpdateBatchOwner.Field()

I'm wondering if there is a more straight forward way to do this?

Update a record via a GraphQL API using Graphene and SQLAlchemy

1 Answers