I am using Express as my backend and for some reason my GET request is not working to query a Postgres database. I am pretty sure I am supposed to use GET request to query the database but can't seem to get it to work. I get the error below.

SyntaxError: Unexpected token < in JSON at position 0

Here is the code for the GET request

const express = require("express");
const router = express.Router();
const pool = require("./db");

router.get("/", async (req, res, next) => {
  pool.connect((err, client, done) => {
    if (err) throw err;
    client.query("SELECT * FROM pledges", (err, ress) => {
      done();
      if (err) {
        console.log(err.stack);
      } else {
        console.log(ress.rows[0]);
        res.json(ress.rows.reverse());
      }
    });
  });

});

However, if I change it to a POST request, I get the correct query and returns the whole table. What am I doing wrong?

const express = require("express");
const router = express.Router();
const pool = require("./db");

router.post("/", async (req, res, next) => {
  pool.connect((err, client, done) => {
    if (err) throw err;
    client.query("SELECT * FROM pledges", (err, ress) => {
      done();
      if (err) {
        console.log(err.stack);
      } else {
        console.log(ress.rows[0]);
        res.json(ress.rows.reverse());
      }
    });
  });

});

Here is my FETCH

  useEffect(() => {
fetch("/pledges")
  .then((response) => response.json())
  .then((data) => {
    console.log(data);
    setPledges(data);
  })
  .catch((error) => {});
  }, []);

Fetch with POST request

  useEffect(() => {
fetch("/pledges", {
  method: "POST",
})
  .then((response) => response.json())
  .then((data) => {
    setPledges(data);
  })
  .catch((error) => {});
  }, []);

CodePudding user response：

Likely the server is returning something that is not JSON, something with a "<" in it, like XML or HTML. Try setting the content header appropriately.

fetch(url, {
  method: "GET",
  headers: {
    "Content-Type": "application/json"
  }
})