Fetching data over relationships

Let’s assume that we have an array relationship from the author table to the article table and an object relationship from the article table to the author table.

To obtain the author’s name from the article table, we issue,

GraphQL
JSON API
query fetch_articles {
  article (where: {is_published: {_eq: true}}) {
     title
     author {
        name
     }
  }
}

POST data.<cluster-name>.hasura-app.io/v1/query HTTP/1.1
Content-Type: application/json
Authorization: Bearer <auth-token> # optional if cookie is set
X-Hasura-Role: <role>  # optional. Pass if only specific user role has access

{
    "type" : "select",
    "args" : {
        "table" : "article",
        "columns": [
            "title",
            {
                "name": "author",
                "columns": ["name"]
            }
        ],
        "where" : {"is_published" : true}
    }
}

The same syntax can be used to obtain the titles of all articles across all authors.

GraphQL
JSON API
query fetch_authors {
  author {
     name
     articles {
        title
     }
  }
}

POST data.<cluster-name>.hasura-app.io/v1/query HTTP/1.1
Content-Type: application/json
Authorization: Bearer <auth-token> # optional if cookie is set
X-Hasura-Role: <role>  # optional. Pass if only specific user role has access

{
    "type" : "select",
    "args" : {
        "table" : "author",
        "columns": [
            "name",
            {
                "name": "articles",
                "columns": ["title"]
            }
        ]
    }
}

You can use relationships inside where clause. For example, if we wish to only fetch all published articles by author with name Warren , we could :

GraphQL
JSON API
query fetch_articles {
  article (where: { is_published: true, author: {name: "Warren"}}) {
     id
     title
     author {
        name
     }
  }
}

POST data.<cluster-name>.hasura-app.io/v1/query HTTP/1.1
Content-Type: application/json
Authorization: Bearer <auth-token> # optional if cookie is set
X-Hasura-Role: <role>  # optional. Pass if only specific user role has access

{
    "type" : "select",
    "args" : {
        "table" : "article",
        "columns": [ "id", "title"],
        "where" : {
            "is_published" : true,
            "author" : {
                "name" : "Warren"
            }
        }
    }
}

Let’s fetch authors who have never published anything.

GraphQL
JSON API
query fetch_author {
  author (where: { $not: { article: { $any: { is_published: true}}}}) {
     id
     name
  }
}

POST data.<cluster-name>.hasura-app.io/v1/query HTTP/1.1
Content-Type: application/json
Authorization: Bearer <auth-token> # optional if cookie is set
X-Hasura-Role: <role>  # optional. Pass if only specific user role has access

{
    "type" : "select",
    "args" : {
        "table" : "author",
        "columns": ["name"],
        "where" : {
            "$not" : {
                "articles" : { "$any" : { "is_published" : true }}
            }
        }
    }
}

As you probably guessed, relationships can be nested. Let’s get all published articles with author information, comments and the author who posted the comment.

GraphQL
JSON API
query fetch_article {
  article (where: {is_published: true}) {
     title
     author {
        name
     }
     comments {
        comment
        commented_by {
           name
        }
     }
  }
}

POST data.<cluster-name>.hasura-app.io/v1/query HTTP/1.1
Content-Type: application/json
Authorization: Bearer <auth-token> # optional if cookie is set
X-Hasura-Role: <role>  # optional. Pass if only specific user role has access

{
    "type" : "select",
    "args" : {
        "table" : "article",
        "columns": [
            "title",
            {
                "name": "author",
                "columns": ["name"]
            },
            {
                "name" : "comments",
                "columns" : [
                    "comment",
                    {
                        "name" : "commented_by",
                        "columns" : ["name"]
                    }
                ]
            }
        ],
        "where" : {"is_published" : true}
    }
}

We can also use where, limit, offset inside array relationships. Let’s say we want to fetch all authors and only their published articles:

GraphQL
JSON API
query fetch_article {
   author {
     articles (where: {is_published: true}) {
        title
     }
   }
}

POST data.<cluster-name>.hasura-app.io/v1/query HTTP/1.1
Content-Type: application/json
Authorization: Bearer <auth-token> # optional if cookie is set
X-Hasura-Role: <role>  # optional. Pass if only specific user role has access

{
    "type" : "select",
    "args" : {
        "table" : "author",
        "columns": [
            "name",
            {
                "name": "articles",
                "columns": ["title"],
                "where" : { "is_published" : true }
            }
        ]
    }
}
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