Map database records to Go structs

Let’s suppose the database we’re working on has a “books” table that was created like this:

CREATE TABLE "books" (
  "id" INTEGER NOT NULL,
  "title" VARCHAR NOT NULL,
  "author_id" INTEGER,
  "subject_id" INTEGER,
  CONSTRAINT "books_id_pkey" PRIMARY KEY ("id")
);

We can represent a single record from such a table and the fields accompanying it with a Go struct accompanied by struct tags in exported fields:

type Book struct {
  ID          uint   `db:"id"`
  Title       string `db:"title"`
  AuthorID    uint   `db:"author_id"`
  SubjectID   uint   `db:"subject_id"`
}

The db field tag is required so upper/db can map columns to struct fields.

Please note that:

• Fields and columns must be of compatible types (upper/db will handle most reasonable conversions automatically).
• Fields must be exported and have a db tag; otherwise, they will be ignored.

If the table contains a special column to represent automatically-generated values like IDs, serials, dates, etc. add the omitempty option to the field tag:

type Book struct {
  ID uint `db:"id,omitempty"`
}

The omitempty option will make upper/db ignore zero-valued fields when building INSERT and UPDATE statements so the database can correctly generate them.