Laravel only get models where all relationships have a specific value (e.g., only get models where all relationships are "friends")?

Updated: Feb 21, 2025

Laravel only get models where all relationships have a specific value (e.g., only get models where all relationships are "friends")?

To answer your question, let me first clarify some terminology. In graph theory and network analysis, a graph is a collection of nodes (also called vertices) and edges that connect pairs of nodes. The relationships between nodes can take on various values, such as "friends," "enemies," "neutral," or no value at all. A subgraph is a subset of nodes and edges from the original graph.

Now, to your question: it is possible to extract subgraphs from a larger graph where all relationships have a specific value. This can be done using graph algorithms such as depth-first search (DFS) or breadth-first search (BFS) in combination with filtering nodes based on their relationship values.

For example, suppose we have a graph representing social relationships between people, where each edge represents a "friend" relationship. We can use DFS or BFS to traverse the graph starting from a seed node and recursively add nodes that are connected to the current node by a "friend" relationship. By stopping the traversal as soon as we encounter a node with a non-friend relationship, we can obtain a subgraph where all relationships are friends.

Here's a more formal description of the algorithm:

  1. Choose a seed node in the graph.
  2. Use DFS or BFS to traverse the graph starting from the seed node, adding nodes and edges to the subgraph as long as the relationship between the current node and the neighboring node is "friend."
  3. Stop the traversal as soon as a node with a non-friend relationship is encountered.
  4. Return the subgraph as the result.

This algorithm can be implemented efficiently using standard graph algorithms libraries in various programming languages, such as NetworkX in Python or Boost.Graph in C++.

However, it's important to note that extracting subgraphs where all relationships have a specific value may not always be possible or meaningful, depending on the structure of the original graph. For example, if the graph is disconnected, there may be no subgraph where all relationships have a specific value. In such cases, it may be more useful to consider other graph properties or subgraphs that better capture the desired relationships or patterns.