See Argus-Labs/world-engine@9e257f5 from refs/heads/main

cardinal/main.go

@@ -33,7 +33,7 @@ func main() {
 	// Register queries
 	// NOTE: You must register your queries here for it to be accessible.
 	Must(
-		cardinal.RegisterQuery[query.WorldVarsRequest, query.WorldVarsResponse](w, "world-vars", query.WorldVars),
+		cardinal.RegisterQuery[query.PlayerHealthRequest, query.PlayerHealthResponse](w, "player-health", query.PlayerHealth),
 	)
 
 	// Each system executes deterministically in the order they are added.

cardinal/query/query_player_health.go

@@ -0,0 +1,53 @@
+package query
+
+import (
+	"fmt"
+
+	comp "github.com/argus-labs/starter-game-template/cardinal/component"
+
+	"pkg.world.dev/world-engine/cardinal"
+)
+
+type PlayerHealthRequest struct {
+	Nickname string
+}
+
+type PlayerHealthResponse struct {
+	HP int
+}
+
+func PlayerHealth(world cardinal.WorldContext, req *PlayerHealthRequest) (*PlayerHealthResponse, error) {
+	search, err := world.NewSearch(cardinal.Exact(comp.Player{}, comp.Health{}))
+	if err != nil {
+		return nil, err
+	}
+
+	var playerHealth *comp.Health
+	err = search.Each(world, func(id cardinal.EntityID) bool {
+		player, err := cardinal.GetComponent[comp.Player](world, id)
+		if err != nil {
+			return false
+		}
+
+		// Terminates the search if the player is found
+		if player.Nickname == req.Nickname {
+			playerHealth, err = cardinal.GetComponent[comp.Health](world, id)
+			if err != nil {
+				return false
+			}
+			return false
+		}
+
+		// Continue searching if the player is not the target player
+		return true
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	if playerHealth == nil {
+		return nil, fmt.Errorf("player %s does not exist", req.Nickname)
+	}
+
+	return &PlayerHealthResponse{HP: playerHealth.HP}, nil
+}