.. meta::
   :description: Manage remote relationships with the Hasura schema/metadata API
   :keywords: hasura, docs, schema/metadata API, API reference, remote joins, remote relationships

Schema/Metadata API Reference: Remote Relationships
===================================================

.. contents:: Table of contents
  :backlinks: none
  :depth: 1
  :local:

Remote Relationships allow you to join tables with remote schemas.

.. _create_remote_relationship:

create_remote_relationship
--------------------------

``create_remote_relationship`` is used to create a new remote relationship with an existing remote schema.

.. code-block:: http

   POST /v1/query HTTP/1.1
   Content-Type: application/json
   X-Hasura-Role: admin

   {
      "type":"create_remote_relationship",
      "args":{
         "name": "sample_remote_relationship",
         "table": "users",
         "hasura_fields": ["id"],
         "remote_schema": "my-remote-schema",
         "remote_field": {
           "messages": {
              "arguments": {
                 "id":"$id"
              }
           }
         }
      }
   }

.. _create_remote_relationship_syntax:

Args syntax
^^^^^^^^^^^

.. list-table::
   :header-rows: 1

   * - Key
     - Required
     - Schema
     - Description
   * - name
     - true
     - RemoteRelationshipName_
     - Name of the remote relationship
   * - table
     - true
     - :ref:`QualifiedTable <QualifiedTable>`
     - Object with table name and schema
   * - hasura_fields
     - true
     - [:ref:`PGColumn <PGColumn>`]
     - Column(s) in the table that is used for joining with remote schema field. All join keys in ``remote_field`` must appear here.
   * - remote_schema
     - true
     - :ref:`RemoteSchemaName <RemoteSchemaName>`
     - Name of the remote schema to join with
   * - remote_field
     - true
     - RemoteField_
     - The schema tree ending at the field in remote schema which needs to be joined with.

.. _update_remote_relationship:

update_remote_relationship
--------------------------

``update_remote_relationship`` is used to update an existing remote relationship.

.. code-block:: http

   POST /v1/query HTTP/1.1
   Content-Type: application/json
   X-Hasura-Role: admin

   {
     "type": "update_remote_relationship",
     "args": {
        "name": "sample_remote_relationship",
        "table": "users",
        "hasura_fields": ["id"],
        "remote_schema": "my-remote-schema",
        "remote_field": {
          "posts": {
             "arguments": {
                "id": "$id",
                "likes": {
                   "lte":"1000"
                }
             }
          }
        }
     }
   }

.. _update_remote_relationship_syntax:

Args syntax
^^^^^^^^^^^

.. list-table::
   :header-rows: 1

   * - Key
     - Required
     - Schema
     - Description
   * - name
     - true
     - RemoteRelationshipName_
     - Name of the remote relationship
   * - table
     - true
     - :ref:`QualifiedTable <QualifiedTable>`
     - Object with table name and schema
   * - hasura_fields
     - true
     - [:ref:`PGColumn <PGColumn>`]
     - Column(s) in the table that is used for joining with remote schema field. All join keys in ``remote_field`` must appear here.
   * - remote_schema
     - true
     - :ref:`RemoteSchemaName <RemoteSchemaName>`
     - Name of the remote schema to join with
   * - remote_field
     - true
     - RemoteField_
     - The schema tree ending at the field in remote schema which needs to be joined with.

.. _delete_remote_relationship:

delete_remote_relationship
--------------------------

``delete_remote_relationship`` is used to delete an existing remote relationship.

.. code-block:: http

   POST /v1/query HTTP/1.1
   Content-Type: application/json
   X-Hasura-Role: admin

   {
       "type" : "delete_remote_relationship",
       "args" : {
          "table":{
             "name":"users",
             "schema":"public"
          },
          "name":"sample_remote_relationship"
       }
   }

.. _delete_remote_relationship_syntax:

Args syntax
^^^^^^^^^^^

.. list-table::
   :header-rows: 1

   * - Key
     - Required
     - Schema
     - Description
   * - table
     - true
     - :ref:`QualifiedTable <QualifiedTable>`
     - Object with table name and schema
   * - name
     - true
     - RemoteRelationshipName_
     - Name of the remote relationship

.. _RemoteRelationshipName:

RemoteRelationshipName
&&&&&&&&&&&&&&&&&&&&&&

.. parsed-literal::

  String


RemoteField
&&&&&&&&&&&

.. parsed-literal::
   :class: haskell-pre

   {
      FieldName: {
        "arguments": InputArguments
        "field": RemoteField  # optional
      }
   }


``RemoteField`` is a recursive tree structure that points to the field in the remote schema that needs to be joined with. It is recursive because the remote field maybe nested deeply in the remote schema.

Examples:

.. code-block:: http

   POST /v1/query HTTP/1.1
   Content-Type: application/json
   X-Hasura-Role: admin

   {
      "message": {
         "arguments":{
            "message_id":"$id"
          }
      }
   }

.. code-block:: http

   POST /v1/query HTTP/1.1
   Content-Type: application/json
   X-Hasura-Role: admin

   {
      "messages": {
         "arguments": {
            "limit": 100
         },
         "field": {
           "private": {
             "arguments": {
                "id" : "$id"
             }
           }
         }
      }
   }

InputArguments
&&&&&&&&&&&&&&

.. parsed-literal::
   :class: haskell-pre

   {
     InputField : $PGColumn | Scalar
   }

Table columns can be referred by prefixing ``$`` e.g ``$id``.