1## Create migrations
2Let's create nodes called `Users`:
3```
4migrate create -ext cypher -dir db/migrations -seq create_user_nodes
5```
6If there were no errors, we should have two files available under `db/migrations` folder:
7- 000001_create_user_nodes.down.cypher
8- 000001_create_user_nodes.up.cypher
9
10Note the `cypher` extension that we provided.
11
12In the `.up.cypher` file let's create the table:
13```
14CREATE (u1:User {name: "Peter"})
15CREATE (u2:User {name: "Paul"})
16CREATE (u3:User {name: "Mary"})
17```
18And in the `.down.sql` let's delete it:
19```
20MATCH (u:User) WHERE u.name IN ["Peter", "Paul", "Mary"] DELETE u
21```
22Ideally your migrations should be idempotent. You can read more about idempotency in [getting started](GETTING_STARTED.md#create-migrations)
23
24## Run migrations
25```
26migrate -database ${NEO4J_URL} -path db/migrations up
27```
28Let's check if the table was created properly by running `bin/cypher-shell -u neo4j -p password`, then `neo4j> MATCH (u:User)`
29The output you are supposed to see:
30```
31+-----------------------------------------------------------------+
32| u |
33+-----------------------------------------------------------------+
34| (:User {name: "Peter") |
35| (:User {name: "Paul") |
36| (:User {name: "Mary") |
37+-----------------------------------------------------------------+
38```
39Great! Now let's check if running reverse migration also works:
40```
41migrate -database ${NEO4J_URL} -path db/migrations down
42```
43Make sure to check if your database changed as expected in this case as well.
44
45## Database transactions
46
47To show database transactions usage, let's create another set of migrations by running:
48```
49migrate create -ext cypher -dir db/migrations -seq add_mood_to_users
50```
51Again, it should create for us two migrations files:
52- 000002_add_mood_to_users.down.cypher
53- 000002_add_mood_to_users.up.cypher
54
55In Neo4j, when we want our queries to be done in a transaction, we need to wrap it with `:BEGIN` and `:COMMIT` commands.
56Migration up:
57```
58:BEGIN
59
60MATCH (u:User)
61SET u.mood = "Cheery"
62
63:COMMIT
64```
65Migration down:
66```
67:BEGIN
68
69MATCH (u:User)
70SET u.mood = null
71
72:COMMIT
73```
74
75## Optional: Run migrations within your Go app
76Here is a very simple app running migrations for the above configuration:
77```
78import (
79 "log"
80
81 "github.com/golang-migrate/migrate/v4"
82 _ "github.com/golang-migrate/migrate/v4/database/neo4j"
83 _ "github.com/golang-migrate/migrate/v4/source/file"
84)
85
86func main() {
87 m, err := migrate.New(
88 "file://db/migrations",
89 "neo4j://neo4j:password@localhost:7687/")
90 if err != nil {
91 log.Fatal(err)
92 }
93 if err := m.Up(); err != nil {
94 log.Fatal(err)
95 }
96}
97```View as plain text