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Official Dgraph client implementation for JavaScript (Node.js v6 and above), using gRPC.
Looking for browser support? Check out dgraph-js-http.
This client follows the Dgraph Go client closely.
Before using this client, we highly recommend that you go through docs.dgraph.io, and understand how to run and work with Dgraph.
Install using npm:
npm install dgraph-js grpc --save
# If you are using Typescript, you might also need:
# npm install @types/google-protobuf @types/protobufjs --save-devor yarn:
yarn add dgraph-js grpc
# If you are using Typescript, you might also need:
# yarn add @types/google-protobuf @types/protobufjs --devDepending on the version of Dgraph that you are connecting to, you will have to use a different version of this client.
| Dgraph version | dgraph-js version |
|---|---|
| 1.0.X | 1.X.Y |
| 1.1.X | 2.X.Y |
| 20.03.0 | 20.03.0 |
Note: Only API breakage from v1.X.Y to v2.X.Y is in
the function DgraphClient.newTxn().mutate(). This function returns a messages.Assigned
type in v1.X but a messages.Response type in v2.X.
Build and run the simple project in the examples folder, which
contains an end-to-end example of using the Dgraph JavaScript client. Follow the
instructions in the README of that project.
A DgraphClient object can be initialised 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.
const dgraph = require("dgraph-js");
const grpc = require("grpc");
const clientStub = new dgraph.DgraphClientStub(
// addr: optional, default: "localhost:9080"
"localhost:9080",
// credentials: optional, default: grpc.credentials.createInsecure()
grpc.credentials.createInsecure(),
);
const dgraphClient = new dgraph.DgraphClient(clientStub);To facilitate debugging, debug mode can be enabled for a client.
To set the schema, create an Operation object, set the schema and pass it to
DgraphClient#alter(Operation) method.
const schema = "name: string @index(exact) .";
const op = new dgraph.Operation();
op.setSchema(schema);
await dgraphClient.alter(op);Starting Dgraph version 20.03.0, indexes can be computed in the background.
You can set setRunInBackground field of the Operation object to true
before passing it to the DgraphClient#alter(Operation) method. You can find more details
here.
const schema = "name: string @index(exact) .";
const op = new dgraph.Operation();
op.setSchema(schema);
op.setRunInBackground(true);
await dgraphClient.alter(op);NOTE: Many of the examples here use the
awaitkeyword which requiresasync/awaitsupport which is available on Node.js >= v7.6.0. For prior versions, the expressions followingawaitcan be used just like normalPromise:dgraphClient.alter(op) .then(function(result) { ... }, function(err) { ... })
Operation contains other fields as well, including drop predicate and drop all.
Drop all is useful if you wish to discard all the data, and start from a clean
slate, without bringing the instance down.
// Drop all data including schema from the Dgraph instance. This is useful
// for small examples such as this, since it puts Dgraph into a clean
// state.
const op = new dgraph.Operation();
op.setDropAll(true);
await dgraphClient.alter(op);To create a transaction, call DgraphClient#newTxn() method, which returns a
new Txn object. This operation incurs no network overhead.
It is good practise 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.
const txn = dgraphClient.newTxn();
try {
// Do something here
// ...
} finally {
await txn.discard();
// ...
}Txn#mutate(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.
We define a person object to represent a person and use it in a Mutation object.
// Create data.
const p = {
name: "Alice",
};
// Run mutation.
const mu = new dgraph.Mutation();
mu.setSetJson(p);
await txn.mutate(mu);For a more 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 use Mutation#setCommitNow(true) to indicate that the
mutation must be immediately committed.
Mutation#setIgnoreIndexConflict(true) can be applied on a Mutation object to
not run conflict detection over the index, which would decrease the number of
transaction conflicts and aborts. However, this would come at the cost of potentially
inconsistent upsert operations.
Mutation can be run using txn.doRequest as well.
const mu = new dgraph.Mutation();
mu.setSetJson(p);
const req = new dgraph.Request();
req.setCommitNow(true);
req.setMutationsList([mu]);
await txn.doRequest(req);You can run a query by calling Txn#query(string). You will need to pass in a
GraphQL+- query string. If you want to pass an additional map of any variables that
you might want to set in the query, call Txn#queryWithVars(string, object) with
the variables object as the second argument.
The response would contain the method Response#getJSON(), which returns the response
JSON.
Let’s run the following query with a variable $a:
query all($a: string) {
all(func: eq(name, $a))
{
name
}
}Run the query, deserialize the result from Uint8Array (or base64) encoded JSON and print it out:
// Run query.
const query = `query all($a: string) {
all(func: eq(name, $a))
{
name
}
}`;
const vars = { $a: "Alice" };
const res = await dgraphClient.newTxn().queryWithVars(query, vars);
const ppl = res.getJson();
// Print results.
console.log(`Number of people named "Alice": ${ppl.all.length}`);
ppl.all.forEach((person) => console.log(person.name));This should print:
Number of people named "Alice": 1
AliceYou can also use txn.doRequest function to run the query.
const req = new dgraph.Request();
const vars = req.getVarsMap();
vars.set("$a", "Alice");
req.setQuery(query);
const res = await txn.doRequest(req);
console.log(JSON.stringify(res.getJson()));The txn.doRequest function allows you to run upserts consisting of one query and one mutation.
Query variables could be defined and can then be used in the mutation. You can also use the
txn.doRequest function to perform just a query or a mutation.
To know more about upsert, we highly recommend going through the docs at https://docs.dgraph.io/mutations/#upsert-block.
const query = `
query {
user as var(func: eq(email, "[email protected]"))
}`
const mu = new dgraph.Mutation();
mu.setSetNquads(`uid(user) <email> "[email protected]" .`);
const req = new dgraph.Request();
req.setQuery(query);
req.setMutationsList([mu]);
req.setCommitNow(true);
// Upsert: If wrong_email found, update the existing data
// or else perform a new mutation.
await dgraphClient.newTxn().doRequest(req);The upsert block 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 Upsert Here.
const query = `
query {
user as var(func: eq(email, "[email protected]"))
}`
const mu = new dgraph.Mutation();
mu.setSetNquads(`uid(user) <email> "[email protected]" .`);
mu.setCond(`@if(eq(len(user), 1))`);
const req = new dgraph.Request();
req.setQuery(query);
req.addMutations(mu);
req.setCommitNow(true);
await dgraphClient.newTxn().doRequest(req);A transaction can be committed using the Txn#commit() method. If your transaction
consisted solely of calls to Txn#query or Txn#queryWithVars, and no calls to
Txn#mutate, then calling Txn#commit() is not necessary.
An error will be returned if other transactions running concurrently modify the same data that was modified in this transaction. It is up to the user to retry transactions when they fail.
const txn = dgraphClient.newTxn();
try {
// ...
// Perform any number of queries and mutations
// ...
// and finally...
await txn.commit();
} catch (e) {
if (e === dgraph.ERR_ABORTED) {
// Retry or handle exception.
} else {
throw e;
}
} finally {
// Clean up. Calling this after txn.commit() is a no-op
// and hence safe.
await txn.discard();
}To cleanup resources, you have to call DgraphClientStub#close() individually for
all the instances of DgraphClientStub.
const SERVER_ADDR = "localhost:9080";
const SERVER_CREDENTIALS = grpc.credentials.createInsecure();
// Create instances of DgraphClientStub.
const stub1 = new dgraph.DgraphClientStub(SERVER_ADDR, SERVER_CREDENTIALS);
const stub2 = new dgraph.DgraphClientStub(SERVER_ADDR, SERVER_CREDENTIALS);
// Create an instance of DgraphClient.
const dgraphClient = new dgraph.DgraphClient(stub1, stub2);
// ...
// Use dgraphClient
// ...
// Cleanup resources by closing all client stubs.
stub1.close();
stub2.close();Debug mode can be used to print helpful debug messages while performing alters,
queries and mutations. It can be set using theDgraphClient#setDebugMode(boolean?)
method.
// Create a client.
const dgraphClient = new dgraph.DgraphClient(...);
// Enable debug mode.
dgraphClient.setDebugMode(true);
// OR simply dgraphClient.setDebugMode();
// Disable debug mode.
dgraphClient.setDebugMode(false);- simple: Quickstart example of using dgraph-js.
- tls: Example of using dgraph-js with a Dgraph cluster secured with TLS.
npm run buildIf you have made changes to the proto/api.proto file, you need need to
regenerate the source files generated by Protocol Buffer tools. To do that,
install the Protocol Buffer Compiler and then run the following
command:
npm run build:protosMake sure you have a Dgraph server running on localhost before you run this task.
npm test