Dgraph query with variable UID

Question

The following code is intended to query a Dgraph server for the values associated with a specific node, similar to looking up a row by primary key in a relational database.

const dgraph = require("dgraph-js");
const grpc = require("grpc");
const clientStub = new dgraph.DgraphClientStub( grpc.credentials.createInsecure() );
const dgraphClient = new dgraph.DgraphClient(clientStub);

const lookupNode = `query nodeValues($id:uid) {
    nodeValues(func: uid($id)) {
        value1,
        value2,
        value3
    }
}`;
const res = await dgraphClient.newTxn().queryWithVars(query, {$id: "0x13");

This raises Error: 2 UNKNOWN: Type "uid" not supported when executing. If the $id variable is typed as a string or int no results are found. How does one query by UID of a node with variables?

Have you ran same query in ratel and does it return a result? Also maybe fields dont exist on the node? — Binier, May 06 '20 at 15:12

score 0 · Answer 1 · answered Jan 31 '20 at 11:34

The type of the $id query variable in this case should be string. It would be helpful to see the actual output that you have. Nevertheless I assume there is a problem with asynchronous functions in your example. The following code gives me the desired output { nodeValues: [ { value1: 'value1' } ] }:

const dgraph = require("dgraph-js");
const grpc = require("grpc");
const clientStub = async () => new dgraph.DgraphClientStub("localhost:9080", grpc.credentials.createInsecure());
const dgraphClient = async (clientStub) => new dgraph.DgraphClient(clientStub);

async function createData(dgraphClient) {
    const txn = dgraphClient.newTxn();
    try {
        const p = {uid: "0x13", value1: "value1"};
        const mu = new dgraph.Mutation();
        mu.setSetJson(p);
        await txn.mutate(mu);
        await txn.commit();
    } finally {
        await txn.discard();
    }
}

const lookupNode = `query nodeValues($id:string) {
    nodeValues(func: uid($id)) {
        value1,
        value2,
        value3
    }
}`;
const res = async (dgraphClient) => {
    const response = await dgraphClient.newTxn().queryWithVars(lookupNode, {$id: "0x13"});
    return response.getJson();
};

const main = async () => {
    const stub = await clientStub();
    const client = await dgraphClient(stub);
    await createData(client);
    return await res(client);
};

main().then((res) => {
    console.log(res);
}).catch((e) => {
    console.log("ERROR: ", e);
});

Based on the example from the officially supported client: https://github.com/dgraph-io/dgraph-js/blob/master/examples/simple/index.js

score 0 · Answer 2 · answered May 31 '21 at 04:25

const dgraph = require("dgraph-js");
const grpc = require("grpc");
const clientStub = new dgraph.DgraphClientStub( grpc.credentials.createInsecure() );
const dgraphClient = new dgraph.DgraphClient(clientStub);

const lookupNode = `query nodeValues(**$id:string**) {
    nodeValues(func: uid($id)) {
        value1,
        value2,
        value3
    }
}`;
const res = await dgraphClient.newTxn().queryWithVars(query, {$id: "0x13");

Use String as data type for your uid :)

Dgraph query with variable UID

2 Answers2