GraphQL request error - Unknown argument 'slug'

Question

I am trying to link my index.js page to an article template to display the data from a middleware Drupal site using a slug and createPages. I have the data displaying correctly on my index.js page and my createPages seems to not have any errors after changing the file path to ./src/templates/article.js.

I am running into this GraphQL error while compiling:

error GraphQL Error There was an error while compiling your site's GraphQL queries. Error: RelayParser: Encountered 1 error(s): - Unknown argument 'slug'. Source: document usersBrooksrelytHtdocsRepositoryGatsbyGraphqlGatsbySrcTemplatesArticleJs4119530598 file: GraphQL request

  GraphQL request (3:12)
  2:   query($slug: String!) {
  3:     umdHub(slug: { eq: $slug }) {
                ^
  4:       articles {

My article.js code:

import React from 'react'
import { graphql } from 'gatsby'
import { ListGroup, ListGroupItem } from 'reactstrap';

// eslint-disable-next-line
import Layout from "../components/layout"
import Header from "../components/header"
import Footer from "../components/footer"


export default ({ data }) => {
  return (
    <div>
      <Header />
      <div className="container spaces article">
        <div className="row">
          <section className="col-md-9">
            <div className="tag-list">
              <ul class="list-inline">
                <li class="list-inline-item"><a href="/">Highlighted</a></li>
                <li class="list-inline-item"><a href="/">Innovation</a></li>
                <li class="list-inline-item"><a href="/">Web Only</a></li>
                <li class="list-inline-item">February 28, 2019</li>
              </ul>
            </div>
            <h1>{data.title}</h1>
            {data.hero_image.map((hero, i) => (
              <div key={i}>
                <img className="img-fluid no-pad-top med-spaces" src={hero.url_1200_630} alt=" " />
              </div>
            ))}
            <div className="row article-content">
              <div className="col-md-10 offset-md-1">
                <h2 className="subheader">{data.subtitle}</h2>
                <div className="author"> 
                  <p>By <a href="/">Jane Doe</a> | Photos by <a href="/">ISTOCK</a></p>
                  <hr />
                </div>
                <div>
                  <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod
                  tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,
                  quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo
                  consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse
                  cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non
                  proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>
                </div>
              </div>
            </div>
          </section>
          <aside className="col-md-3">
            <div>
              <ListGroup flush>
                <ListGroupItem disabled tag="a" href="#">Recent Posts</ListGroupItem>
                <ListGroupItem tag="a" href="#">Dapibus ac facilisis in</ListGroupItem>
                <span>February 27, 2019</span>
                <ListGroupItem tag="a" href="#">Morbi leo risus</ListGroupItem>
                <span>February 27, 2019</span>
                <ListGroupItem tag="a" href="#">Porta ac consectetur ac</ListGroupItem>
                <span>February 27, 2019</span>
                <ListGroupItem tag="a" href="#">Vestibulum at eros</ListGroupItem>
                <span>February 27, 2019</span>
              </ListGroup>
            </div>
          </aside>
        </div>
      </div>


      <Footer />
    </div>

  )
}


export const query = graphql`
  query($slug: String!) {
    umdHub(slug: { eq: $slug }) {
      articles {
        data {
          id
          title
          subtitle
          body
          summary
          hero_image {
            url_1200_630
          }
          authorship_date {
            formatted_short
            unix
            unix_int
            formatted_long
            formatted_short
            time
          }
          slug
        }
      }
    }
  }
`

My gatsby-node.js:

const path = require(`path`)

exports.createPages = ({ graphql, actions }) => {
  const { createPage } = actions
  const articleTemplate = path.resolve(`./src/templates/article.js`)
  return graphql(`
    {
        umdHub {
          articles {
            data {
              id
              title
              subtitle
              body
              summary
              hero_image {
                url_1200_630
              }
              authorship_date {
                formatted_short
                unix
                unix_int
                formatted_long
                formatted_short
                time
              }
              slug
            }
          }
        }
      }
  `).then(result => {
    if (result.errors) {
      throw result.errors
    }

    result.data.umdHub.articles.data.forEach(data => {
      createPage({
        path: `${data.slug}`,
        component: articleTemplate,
        context: {

        },
      })
    })
  })
}

Answer 1

The shortcut for filter only works on field of immediate node, i.e you may filter umdHub by articles. So when you filter by slug, it looks for field slug in umdHub, which doesn't exist because slug is under umdHub.articles.data instead.

This might help:

export const query = graphql`
  query($slug: String!) {

-   umdHub(slug: { eq: $slug }) {
+   umdHub(articles: { data: { slug: { eq: $slug } } }) {

      articles {
        data {
          slug
        }
      }
    }
  }