Here are some of the contenders:

gorm (19.6k stars in github)

• Supports multiple SQL DBs

xorm (6.1k stars on github)

• Supports multiple SQL DBs
• Used by gitea, gogs, grafana,

pg (3.9k stars in github)

• PostgreSQL only
  • if we decide to change DB in the future, choosing this will mean more changes in the DB layer code
  • we may end up using specific features of PostgreSQL making it harder to switch DB in the future

from hermez-node.

Here's an example of using xorm to store structs with custom marshalers:

• struct definition (see xorm tags): https://github.com/iden3/go-iden3-servers-demo/blob/master/servers/issuerdemo/messages/messages.go#L17
• struct usage: https://github.com/iden3/go-iden3-servers-demo/blob/master/servers/issuerdemo/requests.go#L27
  The core.ID and merkletree.Entry are custom types, and they are serialized and deserialized in the DB with the MarshalJSON and UnmarshalJSON methods.
  The validation tags in the example were only used for the HTTP API, to validate user JSON requests.

from hermez-node.

We've choosen to go with:

• Meddler: Map structs <===> tables
• sql-migrate: Handle schema migrations
• SQLx: Simple interface with SQL backends

from hermez-node.