This directory contains a number of different examples showing useful ways to
use pggen. They contain checked in versions of the generated code and an
output.txt file showing what they print so that you don't have to go to
the trouble of running them if you don't want to. Because it is checked in
when the example is first written, the generated code may not be entirely
up to date with the most recent master version of pggen.
First, cd into the example directory, then set up the database
> createdb pggen_development
> psql pggen_development < db.sqlMake sure that $DB_URL is postgres://localhost/pggen_development?sslmode=disable either
by explicitly setting it in the environment with
export DB_URL=postgres://localhost/pggen_development?sslmode=disableor by installing direnv and doing direnv allow at the repo root (this will source the
.envrc file).
Finally, run the program
> go run ./main.goThis example shows how to configure a query to be run against the database.
This example shows how to configure a statement to be executed against the database.
This example shows how to add methods containing business logic to the model
structs generated by pggen. This can help you avoid an error prone and labor
intensive manual translation from the model structs to an extra layer just so
you can define methods on the intermediate layer.
This example shows how to use the upsert interface that pggen will automatically generate for each model struct generated from a table.
This example shows how to write a query that checks for set containment
using the = ANY idiom rather than the IN operator that is typically
used with other database interactivity libraries.
This example shows how to use include specs to tell pggen how to fill in records which are associated with one another via foreign keys. Include specs are the key to the way that pggen deals with associations.
This example shows how to make use of the automatic timestamp features that pggen provides. You can ask pggen to automatically take care of keeping track created at and updated at timestamps. Soft deletes are often implemented with a timestamp rather than just a boolean flag, so pggen supports them using similar machinery, which is also demonstrated in this example.
This example shows how to provide useful names for query arguments. You can also provide useful names for query arguments by defining a stored function and telling pggen to generate shims for it, but you may prefer to avoid the ceremony usually involved in managing objects in a database.
This example shows how to inject middleware between the generated PGClient and the database
connection. This allows you to implement things like logging and tracing to see what queries
are getting run against the database.
This example shows how to write queries that return just a single row as a result using
the single_result configuration option. This is a small quality of life improvement over
having to unpack a slice each time you place a query.
This example shows how to ask pggen to generate conversion code between arbitrary go
types and json or jsonb types in postgres.
This example shows how to ask pggen to generate code which allows nils to be passed into
queries. By default, you can only pass concrete types like string and int into a
pggen query.
This example shows how to work postgres's uuid type using the github.com/gofrs/uuid
library. There is no uuid type in the go standard library, so you must use a third party
type. pggen does not want to force a hard dependency on any particular uuid library, so
you must explicitly configure a type override in order to work with uuids.
This example shows how to generate a statement with that accepts nullable arguments. By default, you can only pass in non NULL values to statements, since this is generally more convenient, but if you want you can explicitly ask pggen to allow you to pass in NULL values.