08-FindByMutualFriendsAndGroups

README

DM.08 Find people based on mutual friends and groups

Listing Functions

Standard practice

func listUsers() {...}
func listGroups() {...}

Sublists

func listGroupMembers(group string) {
	stmt := `
		MATCH (user:User)-[:member_of_group]->(group:Group)
		WHERE group.name = {groupSub}
		RETURN user.name
		ORDER BY user.name
	`

	params := neoism.Props{"groupSub": group}

	res := []struct {
		User string `json:"user.name"`
	}{}

	...
}

func listUserGroups(user string) {
	stmt := `
		MATCH (user:User)-[:member_of_group]->(group:Group)
		WHERE user.name = {userSub}
		RETURN group.name
		ORDER BY group.name
	`

	params := neoism.Props{"userSub": user}

	res := []struct {
		Group string `json:"group.name"`
	}{}

	...
}

func listUserFriends(user string) {
	stmt := `
		MATCH (user:User)-[:knows]->(friend:User)
		WHERE user.name = {userSub}
		RETURN friend.name
		ORDER BY friend.name
	`

	params := neoism.Props{"userSub": user}

	res := []struct {
		Friend string `json:"friend.name"`
	}{}

	...
}

Finding Mutuals

Here, we are trying to find the number of paths (through friends or groups) to the user to the other user.

OPTIONAL MATCH is used here so that one of the relationships can be optional (equal to 0).

func findMutualsForUser(user string, other string) {
	stmt := `
		MATCH (me:User { name: {userSub} }),(other:User { name: {otherSub} })
		OPTIONAL MATCH pGroups=(me)-[:member_of_group]->(mg)<-[:member_of_group]-(other)
		OPTIONAL MATCH pMutualFriends=(me)-[:knows]->(mf)<-[:knows]-(other)
		RETURN other.name AS name, collect(mg.name) AS mutualGroups,
		  collect(DISTINCT mf.name) AS mutualFriends
		ORDER BY length(collect(DISTINCT mf.name)) DESC
	`

	// othersStr := "['" + others[0]
	// for i, o := range others {
	// 	if i < 1 {
	// 		continue
	// 	}
	// 	othersStr += "', '" + o
	// }
	// othersStr += "']"
	// fmt.Println("others: ", othersStr)

	// ERROR  othersStr doesn't substitute well
	// WHERE other.name IN {othersSub} --> ['Jill', 'Bob']
	// params := neoism.Props{"userSub": user, "othersSub": othersStr}

	params := neoism.Props{"userSub": user, "otherSub": other}

	res := []struct {
		Name    string   `json:"name"`
		Groups  []string `json:"mutualGroups"`
		Friends []string `json:"mutualFriends"`
	}{}

	// construct query
	cq := neoism.CypherQuery{
		Statement:  stmt,
		Parameters: params,
		Result:     &res,
	}

	// execute query
	err := db.Cypher(&cq)
	panicErr(err)

	fmt.Println("Mutuals of", user, ":")
	if len(res) > 0 {
		fmt.Printf("%-12s  %-14s  %-14s\n", "Name", "Groups", "Friends")
		for _, n := range res {
			fmt.Printf("  %-10s  %v  %v\n", n.Name, n.Groups, n.Friends)
		}
	} else {
		fmt.Println("No results found")
	}
}