dgraph-io/pydgraph

pydgraph

This is the official Dgraph database client implementation for Python (Python >= v3.9), using gRPC.

Before using this client, we highly recommend that you read the the product documentation at https://docs.dgraph.io/.

Table of contents

• pydgraph
  • Table of contents
  • Install
  • Supported Versions
  • Quickstart
  • Using a client
    • Creating a Client
    • Login into a Namespace
    • Altering the Database
    • Creating a Transaction
    • Running a Mutation
    • Running a Query
    • Query with RDF response
    • Running an Upsert: Query + Mutation
    • Running a Conditional Upsert
    • Committing a Transaction
    • Cleaning Up Resources
    • Setting Metadata Headers
    • Setting a timeout
    • Async methods
    • Native Async/Await Client
  • Handling Transaction Conflicts
    • Using run_transaction (Recommended)
    • Using the Retry Decorator
    • Using the Retry Generator
    • Retry Parameters
    • Which Errors Are Retried?
    • Example: High-Contention Counter
  • Examples
  • Contributing

Install

Install using pip:

pip install pydgraph

Protobuf Version Compatibility

pydgraph supports protobuf versions 4.23.0 through 6.x. The specific version installed depends on your environment:

• Modern environments: protobuf 6.x is recommended and will be installed by default on Python 3.13+
• Legacy environments: If you need to use protobuf 4.x or 5.x (e.g., for compatibility with other packages), you can pin the version:

# For protobuf 4.x compatibility
pip install pydgraph "protobuf>=4.23.0,<5.0.0"

# For protobuf 5.x compatibility
pip install pydgraph "protobuf>=5.0.0,<6.0.0"

All supported protobuf versions are tested in CI against both Dgraph latest and Dgraph HEAD.

Supported Versions

Depending on the version of Dgraph that you are connecting to, you should use a different version of this client. Using an incompatible version may lead to unexpected behavior or errors.

Quickstart

Build and run the simple project in the examples folder, which contains an end-to-end example of using the Dgraph python client. For additional details, follow the instructions in the project's README.

Using a client

Creating a Client

You can initialize a DgraphClient object by passing it a list of DgraphClientStub clients as variadic arguments. Connecting to multiple Dgraph servers in the same cluster allows for better distribution of workload.

The following code snippet shows just one connection.

import pydgraph

client_stub = pydgraph.DgraphClientStub('localhost:9080')
client = pydgraph.DgraphClient(client_stub)

Using Dgraph Connection Strings

The pydgraph package supports connecting to a Dgraph cluster using connection strings. Dgraph connections strings take the form dgraph://{username:password@}host:port?args.

username and password are optional. If username is provided, a password must also be present. If supplied, these credentials are used to log into a Dgraph cluster through the ACL mechanism.

Valid connection string args:

Note the sslmode=require pair is not supported and will throw an Exception if used. Python grpc does not support traffic over TLS that does not fully verify the certificate and domain. Developers should use the existing stub/client initialization steps for self-signed certs as demonstrated in examples/tls/tls_example.py.

Some example connection strings:

Using the Open function with a connection string:

# open a connection to an ACL-enabled, non-TLS cluster and login as groot
client = pydgraph.open("dgraph://groot:password@localhost:8090")

# Use the client
...

client.close()

Login into a Namespace

If your server has Access Control Lists enabled (Dgraph v1.1 or above), the client must be logged in for accessing data. If you didn't use the open function with credentials and a namespace, use the login endpoint.

Calling login will obtain and remember the access and refresh JWT tokens. All subsequent operations via the logged in client will send along the stored access token.

client.login("groot", "password")

If your server additionally has namespaces (Dgraph v21.03 or above), use the login_into_namespace API.

client.login_into_namespace("groot", "password", "123")

Altering the Database

Set the Dgraph types schema

To set the Dgraph types schema (aka DQL schema), create an Operation object, set the schema and pass it to DgraphClient#alter(Operation) method.

schema = 'name: string @index(exact) .'
op = pydgraph.Operation(schema=schema)
client.alter(op)

Indexes can be computed in the background. You can set the run_in_background field of pydgraph.Operation to True before passing it to the Alter function. You can find more details in the Dgraph documentation on background indexes.

Note To deploy the GraphQL schema in python you have to use GraphQL client such as python-graphql-client to invoke the GraphQL admin mutation updateGQLSchema

schema = 'name: string @index(exact) .'
op = pydgraph.Operation(schema=schema, run_in_background=True)
client.alter(op)

Drop data

To drop all data and schema:

# Drop all data including schema from the Dgraph instance. This is a useful
# for small examples such as this since it puts Dgraph into a clean state.
op = pydgraph.Operation(drop_all=True)
client.alter(op)

Note If the Dgraph cluster contains a GraphQL Schema, it will also be deleted by this operation.

To drop all data and preserve the DQL schema:

# Drop all data from the Dgraph instance. Keep the DQL Schema.
op = pydgraph.Operation(drop_op="DATA")
client.alter(op)

To drop a predicate:

# Drop the data associated to a predicate and the predicate from the schema.
op = pydgraph.Operation(drop_op="ATTR", drop_value="<predicate_name>")
client.alter(op)

the same result is obtained using

# Drop the data associated to a predicate and the predicate from the schema.
op = pydgraph.Operation(drop_attr="<predicate_name>")
client.alter(op)

To drop a type definition from DQL Schema:

# Drop a type from the schema.
op = pydgraph.Operation(drop_op="TYPE", drop_value="<predicate_name>")
client.alter(op)

Note drop_op="TYPE" just removes a type definition from the DQL schema. No data is removed from the cluster. The operation does not drop the predicates associated with the type.

Creating a Transaction

To create a transaction, call the DgraphClient#txn() method, which returns a new Txn object. This operation incurs no network overhead.

It is good practice to call Txn#discard() in a finally block after running the transaction. Calling Txn#discard() after Txn#commit() is a no-op and you can call Txn#discard() multiple times with no additional side-effects.

txn = client.txn()
try:
  # Do something here
  # ...
finally:
  txn.discard()
  # ...

To create a read-only transaction, call DgraphClient#txn(read_only=True). Read-only transactions are ideal for transactions which only involve queries. Mutations and commits are not allowed.

txn = client.txn(read_only=True)
try:
  # Do some queries here
  # ...
finally:
  txn.discard()
  # ...

To create a read-only transaction that executes best-effort queries, call DgraphClient#txn(read_only=True, best_effort=True). Best-effort queries are faster than normal queries because they bypass the normal consensus protocol. For this same reason, best-effort queries cannot guarantee to return the latest data. Best-effort queries are only supported by read-only transactions.

Running a Mutation

Txn#mutate(mu=Mutation) runs a mutation. It takes in a Mutation object, which provides two main ways to set data: JSON and RDF N-Quad. You can choose whichever way is convenient.

Txn#mutate() provides convenience keyword arguments set_obj and del_obj for setting JSON values and set_nquads and del_nquads for setting N-Quad values. See examples below for usage.

We define a person object to represent a person and use it in a transaction.

# Create data.
p = { 'name': 'Alice' }

# Run mutation.
txn.mutate(set_obj=p)

# If you want to use a mutation object, use this instead:
# mu = pydgraph.Mutation(set_json=json.dumps(p).encode('utf8'))
# txn.mutate(mu)

# If you want to use N-Quads, use this instead:
# txn.mutate(set_nquads='_:alice <name> "Alice" .')

# Delete data

query = """query all($a: string)
 {
   all(func: eq(name, $a))
    {
      uid
    }
  }"""
variables = {'$a': 'Bob'}

res = txn.query(query, variables=variables)
ppl = json.loads(res.json)

# For a mutation to delete a node, use this:
txn.mutate(del_obj=person)

For a complete example with multiple fields and relationships, look at the simple project in the examples folder.

Sometimes, you only want to commit a mutation, without querying anything further. In such cases, you can set the keyword argument commit_now=True to indicate that the mutation must be immediately committed.

A mutation can be executed using txn.do_request as well.

mutation = txn.create_mutation(set_nquads='_:alice <name> "Alice" .')
request = txn.create_request(mutations=[mutation], commit_now=True)
txn.do_request(request)

Committing a Transaction

A transaction can be committed using the Txn#commit() method. If your transaction consist solely of Txn#query or Txn#queryWithVars calls, and no calls to Txn#mutate, then calling Txn#commit() is not necessary.

An error is raised if another transaction(s) modify the same data concurrently that was modified in the current transaction. It is up to the user to retry transactions when they fail.

txn = client.txn()
try:
  # ...
  # Perform any number of queries and mutations
  # ...
  # and finally...
  txn.commit()
except pydgraph.AbortedError:
  # Retry or handle exception.
finally:
  # Clean up. Calling this after txn.commit() is a no-op
  # and hence safe.
  txn.discard()

Using Transaction with Context Manager

The Python context manager will automatically perform the "commit" action after all queries and mutations have been done, and perform "discard" action to clean the transaction. When something goes wrong in the scope of context manager, "commit" will not be called,and the "discard" action will be called to drop any potential changes.

with client.begin(read_only=False, best_effort=False) as txn:
  # Do some queries or mutations here

or you can directly create a transaction from the Txn class.

with pydgraph.Txn(client, read_only=False, best_effort=False) as txn:
  # Do some queries or mutations here

client.begin() can only be used with "with-as" blocks, while pydgraph.Txn class can be directly called to instantiate a transaction object.

Running a Query

You can run a query by calling Txn#query(string). You will need to pass in a DQL query string. If you want to pass an additional dictionary of any variables that you might want to set in the query, call Txn#query(string, variables=d) with the variables dictionary d.

The query response contains the json field, which returns the JSON response. Let’s run a query with a variable $a, deserialize the result from JSON and print it out:

# Run query.
query = """query all($a: string) {
  all(func: eq(name, $a))
  {
    name
  }
}"""
variables = {'$a': 'Alice'}

res = txn.query(query, variables=variables)

# If not doing a mutation in the same transaction, simply use:
# res = client.txn(read_only=True).query(query, variables=variables)

ppl = json.loads(res.json)

# Print results.
print('Number of people named "Alice": {}'.format(len(ppl['all'])))
for person in ppl['all']:
  print(person)

This should print:

Number of people named "Alice": 1
Alice

You can also use txn.do_request function to run the query.

request = txn.create_request(query=query)
txn.do_request(request)

Query with RDF response

You can get query result as a RDF response by calling Txn#query(string) with resp_format set to RDF. The response would contain a rdf field, which has the RDF encoded result.

Note: If you are querying only for uid values, use a JSON format response.

res = txn.query(query, variables=variables, resp_format="RDF")
print(res.rdf)

Running an Upsert: Query + Mutation

The txn.do_request function allows you to use upsert blocks. An upsert block contains one query block and one or more mutation blocks, so it lets you perform queries and mutations in a single request. Variables defined in the query block can be used in the mutation blocks using the uid and val functions implemented by DQL.

To learn more about upsert blocks, see the Upsert Block documentation.

query = """{
  u as var(func: eq(name, "Alice"))
}"""

nquad = """
  uid(u) <name> "Alice" .
  uid(u) <age> "25" .
"""

mutation = txn.create_mutation(set_nquads=nquad)
request = txn.create_request(query=query, mutations=[mutation], commit_now=True)
txn.do_request(request)

Running a Conditional Upsert

The upsert block also allows specifying a conditional mutation block using an @if directive. The mutation is executed only when the specified condition is true. If the condition is false, the mutation is silently ignored.

See more about conditional upserts in the Dgraph documentation.

query = """
  {
    user as var(func: eq(email, "[email protected]"))
  }
"""

cond = "@if(eq(len(user), 1))"
nquads = """
  uid(user) <email> "[email protected]" .
"""

mutation = txn.create_mutation(cond=cond, set_nquads=nquads)
request = txn.create_request(mutations=[mutation], query=query, commit_now=True)
txn.do_request(request)

Cleaning Up Resources

To clean up resources, you have to call DgraphClientStub#close() individually for all the instances of DgraphClientStub.

SERVER_ADDR1 = "localhost:9080"
SERVER_ADDR2 = "localhost:9080"

# Create instances of DgraphClientStub.
stub1 = pydgraph.DgraphClientStub(SERVER_ADDR1)
stub2 = pydgraph.DgraphClientStub(SERVER_ADDR2)

# Create an instance of DgraphClient.
client = pydgraph.DgraphClient(stub1, stub2)

# Use client
...

# Clean up resources by closing all client stubs.
stub1.close()
stub2.close()

Use context manager to automatically clean resources

Use function call:

with pydgraph.client_stub(SERVER_ADDR) as stub1:
  with pydgraph.client_stub(SERVER_ADDR) as stub2:
    client = pydgraph.DgraphClient(stub1, stub2)

Use class constructor:

with pydgraph.DgraphClientStub(SERVER_ADDR) as stub1:
  with pydgraph.DgraphClientStub(SERVER_ADDR) as stub2:
    client = pydgraph.DgraphClient(stub1, stub2)

Note: client should be used inside the "with-as" block. The resources related to client will be automatically released outside the block and client is not usable any more.

Setting Metadata Headers

Metadata headers such as authentication tokens can be set through the metadata of gRPC methods. Below is an example of how to set a header named "auth-token".

# The following piece of code shows how one can set metadata with
# auth-token, to allow Alter operation, if the server requires it.
# metadata is a list of arbitrary key-value pairs.
metadata = [("auth-token", "the-auth-token-value")]
dg.alter(op, metadata=metadata)

Setting a timeout

A timeout value representing the number of seconds can be passed to the login, alter, query, and mutate methods using the timeout keyword argument.

For example, the following alters the schema with a timeout of ten seconds: dg.alter(op, timeout=10)

Async methods

The alter method in the client has an asynchronous version called async_alter. The async methods return a future. You can directly call the result method on the future. However. The DgraphClient class provides a static method handle_alter_future to handle any possible exception.

alter_future = self.client.async_alter(pydgraph.Operation(schema="name: string @index(term) ."))
response = pydgraph.DgraphClient.handle_alter_future(alter_future)

The query and mutate methods int the Txn class also have async versions called async_query and async_mutation respectively. These functions work just like async_alter.

You can use the handle_query_future and handle_mutate_future static methods in the Txn class to retrieve the result. A short example is given below:

txn = client.txn()
query = "query body here"
future = txn.async_query()
response = pydgraph.Txn.handle_query_future(future)

Keep in mind that due to the nature of async calls, the async functions cannot retry the request if the login is invalid. You will have to check for this error and retry the login (with the function retry_login in both the Txn and Client classes). A short example is given below:

client = DgraphClient(client_stubs) # client_stubs is a list of gRPC stubs.
alter_future = client.async_alter()
try:
    response = alter_future.result()
except Exception as e:
  # You can use this function in the util package to check for JWT
    # expired errors.
    if pydgraph.util.is_jwt_expired(e):
        # retry your request here.

Native Async/Await Client

pydgraph provides a native async/await client using Python's asyncio library and grpc.aio. This provides true asynchronous operations with better concurrency compared to the futures-based approach above.

Basic Usage

import asyncio
import pydgraph

async def main():
    # Create async client
    client_stub = pydgraph.AsyncDgraphClientStub('localhost:9080')
    client = pydgraph.AsyncDgraphClient(client_stub)

    try:
        # Login
        await client.login("groot", "password")

        # Alter schema
        await client.alter(pydgraph.Operation(
            schema="name: string @index(term) ."
        ))

        # Run mutation
        txn = client.txn()
        response = await txn.mutate(
            set_obj={"name": "Alice"},
            commit_now=True
        )

        # Run query
        query = '{ me(func: has(name)) { name } }'
        txn = client.txn(read_only=True)
        response = await txn.query(query)
        print(response.json)

    finally:
        await client.close()

asyncio.run(main())

Using Connection Strings

The async client supports the same connection string format as the sync client:

import asyncio
import pydgraph

async def main():
    # Using async_open with connection string
    async with await pydgraph.async_open(
        "dgraph://groot:password@localhost:9080"
    ) as client:
        version = await client.check_version()
        print(f"Connected to Dgraph version: {version}")

asyncio.run(main())

Using Context Managers

Both the async client and transactions support async context managers for automatic resource cleanup:

import asyncio
import pydgraph

async def main():
    # Client auto-closes on exit
    async with await pydgraph.async_open("dgraph://localhost:9080") as client:
        await client.login("groot", "password")

        # Transaction auto-discards on exit
        async with client.txn() as txn:
            response = await txn.query('{ me(func: has(name)) { name } }')
            print(response.json)

asyncio.run(main())

Concurrent Operations

The async client excels at running many operations concurrently:

import asyncio
import pydgraph

async def run_query(client, name):
    """Run a single query"""
    query = f'{{ me(func: eq(name, "{name}")) {{ name }} }}'
    txn = client.txn(read_only=True)
    return await txn.query(query)

async def main():
    async with await pydgraph.async_open("dgraph://localhost:9080") as client:
        await client.login("groot", "password")

        # Run 100 queries concurrently
        names = [f"User{i}" for i in range(100)]
        tasks = [run_query(client, name) for name in names]
        results = await asyncio.gather(*tasks)

        print(f"Completed {len(results)} queries concurrently")

asyncio.run(main())

JWT Refresh

The async client automatically handles JWT token refresh, just like the sync client:

async with await pydgraph.async_open("dgraph://groot:password@localhost:9080") as client:
    # JWT will be automatically refreshed if it expires during operations
    response = await client.alter(pydgraph.Operation(schema="name: string ."))

Error Handling

Error handling works the same as the sync client:

import pydgraph

async def main():
    async with await pydgraph.async_open("dgraph://localhost:9080") as client:
        try:
            await client.login("groot", "wrong_password")
        except Exception as e:
            print(f"Login failed: {e}")

        try:
            txn = client.txn(read_only=True)
            await txn.mutate(set_obj={"name": "Alice"})
        except pydgraph.errors.TransactionError as e:
            print(f"Cannot mutate in read-only transaction: {e}")

asyncio.run(main())

Differences from Sync Client

Handling Transaction Conflicts

Dgraph uses optimistic concurrency control (MVCC). When multiple transactions modify the same data simultaneously, conflicts can occur and Dgraph will abort one of the transactions with an AbortedError. When this happens, the entire transaction must be retried from scratch.

pydgraph provides built-in retry utilities with exponential backoff to handle these conflicts automatically.

Using run_transaction (Recommended)

The simplest approach - pass your operation as a callable:

import pydgraph

def create_user(txn):
    """Transaction operation that will be retried on conflict."""
    response = txn.mutate(set_obj={"name": "Alice", "age": 30})
    txn.commit()
    return response.uids

client = pydgraph.DgraphClient(pydgraph.DgraphClientStub("localhost:9080"))

# Automatically retries on AbortedError with exponential backoff
result = pydgraph.run_transaction(client, create_user, max_retries=5)
print(f"Created user: {result}")

For async code:

async def create_user_async(txn):
    response = await txn.mutate(set_obj={"name": "Alice", "age": 30})
    await txn.commit()
    return response.uids

result = await pydgraph.run_transaction_async(client, create_user_async)

Using the Retry Decorator

Wrap any function that performs Dgraph operations:

import pydgraph

@pydgraph.with_retry(max_retries=5, base_delay=0.1)
def upsert_counter(client, counter_id):
    """Increment a counter atomically - automatically retried on conflict."""
    txn = client.txn()
    try:
        # Query current value
        query = f'{{ counter(func: uid({counter_id})) {{ value }} }}'
        result = txn.query(query)
        current = json.loads(result.json).get("counter", [{}])[0].get("value", 0)

        # Increment and update
        txn.mutate(set_obj={"uid": counter_id, "value": current + 1})
        txn.commit()
    finally:
        txn.discard()

# Called normally - retries happen transparently
upsert_counter(client, "0x123")

For async functions:

@pydgraph.with_retry_async(max_retries=5)
async def upsert_counter_async(client, counter_id):
    async with client.txn() as txn:
        # ... async operations
        pass

Using the Retry Generator

For fine-grained control within a function:

import pydgraph

def transfer_funds(client, from_account, to_account, amount):
    """Transfer funds between accounts with manual retry control."""
    for attempt in pydgraph.retry(max_retries=5, base_delay=0.1):
        with attempt:
            txn = client.txn()
            try:
                # Perform the transfer (queries and mutations)
                # If AbortedError is raised, retry() handles it
                txn.commit()
            finally:
                txn.discard()

For async code:

async def transfer_funds_async(client, from_account, to_account, amount):
    async for attempt in pydgraph.retry_async(max_retries=5):
        with attempt:
            async with client.txn() as txn:
                # ... async operations
                pass

Retry Parameters

All retry utilities accept these parameters:

Which Errors Are Retried?

Only these errors trigger automatic retries:

• pydgraph.AbortedError - Transaction conflict (optimistic concurrency)
• pydgraph.RetriableError - Transient server errors

All other exceptions propagate immediately.

Example: High-Contention Counter

Here's a complete example handling a high-contention scenario:

import json
import pydgraph

def increment_counter(client, counter_uid):
    """Atomically increment a counter, handling conflicts automatically."""

    def operation(txn):
        # Read current value
        query = f'{{ counter(func: uid({counter_uid})) {{ count }} }}'
        result = txn.query(query)
        data = json.loads(result.json)
        current = data.get("counter", [{}])[0].get("count", 0)

        # Increment
        txn.mutate(set_obj={"uid": counter_uid, "count": current + 1})
        txn.commit()
        return current + 1

    return pydgraph.run_transaction(
        client, operation,
        max_retries=10,   # More retries for high contention
        base_delay=0.05,  # Start with shorter delays
        max_delay=2.0,
        jitter=0.25       # Higher jitter to spread out retries
    )

# Usage
client = pydgraph.DgraphClient(pydgraph.DgraphClientStub("localhost:9080"))
new_value = increment_counter(client, "0x1")
print(f"Counter is now: {new_value}")

Examples

• simple: Quickstart example of using pydgraph.
• tls: Quickstart example that uses TLS.
• parse_datetime: Demonstration of converting Dgraph's DateTime strings to native python datetime.

Contributing

We welcome contributions! Please see CONTRIBUTING.md for detailed information on: /

• Setting up your development environment
• Code style and standards
• Testing procedures
• Submitting pull requests