Connections

Welcome to a quick guide that will help you grasp the core concepts of connections, nodes, and edges as they apply to our GraphQL API.

1. What Are They?

Connection: It’s the link between data points. In GraphQL, a connection models a one-to-many relationship, and it is the heart of pagination.

Node: Represents an individual piece of data in your dataset. Think of nodes as the primary elements you’re trying to fetch.

Edge: Serves as the bridge between connections and nodes. It contains both the node’s data and additional information about the connection, like a cursor for pagination.

2. Visual Representation

Imagine a necklace. The necklace itself is the connection. Each bead on it is a node, and the thread passing through each bead is the edge.

3. Why Use This Model?

• Scalability: This model ensures efficient data fetching, especially when dealing with large datasets.
• Flexibility: It supports intricate pagination and data fetching patterns, such as infinite scrolling.
• Consistency: It provides a standardized way to interact with varying datasets.

4. A Simple Query Example

{
  units(first: 5) {
    edges {
      node {
        id
        name
      }
      cursor
    }
    pageInfo {
      hasNextPage
      endCursor
    }
  }
}

In this example:

• We’re querying a connection called units to fetch the first 5 properties.
• Each edge contains a node (actual property data) and a cursor (used for pagination).
• The pageInfo gives us details about the pagination status.

5. Key Concepts Recap

• Connection: The whole dataset or its subset.
• Node: Individual data items you’re fetching.
• Edge: Contains the node and additional info about its position in the dataset.

6. Best Practices

• While paginating, always use the cursors provided within edges. Manual modifications can lead to unexpected results.
• Familiarize yourself with the specific fields and data types within nodes relevant to your queries.

You can read more in the specification: https://relay.dev/graphql/connections.htm