03-SocialMovieDatabase

README

GS.3 Social Movie Database

In this section, we expand the movie database with features typical of a social website. This means our graph will now have more node types and multiple relationship types. We will also write some generic functions for adding information to the graph.

Creating things:

func createUser(name string) {
	queryNodes("", "", "(n:User {name: '"+name+"'})", "n", "")
}

func createFriendship(user, friend string) {
	match := "(u:User {name: '" + user + "'}),(f:User {name: '" + friend + "'})"
	create := "(u)-[:FRIEND]->(f)"
	queryNodes(match, "", create, "", "")
}

func createRating(user, title, stars, comment string) {
	match := "(u:User {name: '" + user + "'}),(m:Movie {title: '" + title + "'})"
	create := "(u)-[:RATED { stars: " + stars + ", comment: '" + comment + "'}]->(m)"
	queryNodes(match, "", create, "", "")
}

Listing user information:

func getRatingsByUser(user string) {
	stmt := `
		MATCH (u:User {name: {userSub}}),(u)-[rating:RATED]->(movie)
	    RETURN movie, rating;
	`
	params := neoism.Props{"userSub": user}

	res := []struct {
		Movie  neoism.Node
		Rating neoism.Relationship
	}{}

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

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

	fmt.Println("User Ratings: ", user, len(res))
	for i, _ := range res {
		m := res[i].Movie.Data
		r := res[i].Rating.Data.(map[string]interface{})
		fmt.Printf("  [%d] %v    %v    %v\n",
			i, m["title"], r["stars"], r["comment"])
	}
}

func getFriendsByUser(user string) {
	stmt := `
		MATCH (u:User {name: {userSub}}),(u)-[r:FRIEND]->(f)
	    RETURN type(r) AS T, f.name AS F;
	`
	params := neoism.Props{"userSub": user}

	// query results
	res := []struct {
		T string
		F string
	}{}

	// construct query
	cq := neoism.CypherQuery{
		Statement:  stmt,
		Parameters: params,
		Result:     &res,
	}
	// execute query
	err := db.Cypher(&cq)
	panicErr(err)

	fmt.Println("User Friends: ", user, len(res))
	for i, _ := range res {
		n := res[i]
		fmt.Printf("  [%d] %q  %q\n", i, n.T, n.F)
	}
}

Limitations and exercises:

The above functions make use of our queryNodes() function, but do not make use of Neo4j's parameter capabilities. To do so requires a more complicated queryNodes() function, which makes neoism.Props{} or a map[string]string a parameter of the function. We leave this as an exercise for the reader.