Insert test data in a database

When you're developing or testing, it's often useful to seed databases with test data. This can be done is several ways depending on your use case.

Using go:embed

A straightforward way to insert test data is to conditionally insert it on startup using go:embed in combination with Encore's metadata API control in which environments the data gets inserted. E.g. only in your local environment.

Example

Create a file with your test data named fixtures.sql. Then, for the service where you want to insert test data, add the following to its .go file in order to run on startup.

import (
    _ "embed"
    "log"

    "encore.dev"
)

//go:embed fixtures.sql
var fixtures string

func init() {
    if encore.Meta().Environment.Cloud == encore.CloudLocal {
        if _, err := sqldb.Exec(context.Background(), fixtures); err != nil {
            log.Fatalln("unable to add fixtures:", err)
        }
    }
}

Not included in the above example is preventing adding duplicate data. This is straightforward to do by making the fixtures idempotent, or by tracking it with a database table.

Populating databases in Preview Environments

In some cases, it can be useful to populate new Preview Environments with test data to simplify testing.

The best way to do this depends a bit on your use case, but a common way to do this is by using Encore's webooks functionality, which provides notifications for when a deployment is completed and includes information about the environment in question.