golang: Output NullUUID when necessary

internal/codegen/golang/imports.go

@@ -202,6 +202,10 @@ func (i *importer) interfaceImports() fileImports {
 	if uses("uuid.UUID") && !overrideUUID {
 		pkg[ImportSpec{Path: "github.com/google/uuid"}] = struct{}{}
 	}
+	_, overrideNullUUID := overrideTypes["uuid.NullUUID"]
+	if uses("uuid.NullUUID") && !overrideNullUUID {
+		pkg[ImportSpec{Path: "github.com/google/uuid"}] = struct{}{}
+	}
 
 	// Custom imports
 	for _, o := range i.Settings.Overrides {
@@ -263,6 +267,10 @@ func (i *importer) modelImports() fileImports {
 	if i.usesType("uuid.UUID") && !overrideUUID {
 		pkg[ImportSpec{Path: "github.com/google/uuid"}] = struct{}{}
 	}
+	_, overrideNullUUID := overrideTypes["uuid.NullUUID"]
+	if i.usesType("uuid.NullUUID") && !overrideNullUUID {
+		pkg[ImportSpec{Path: "github.com/google/uuid"}] = struct{}{}
+	}
 
 	for _, o := range i.Settings.Overrides {
 		if o.GoBasicType || o.GoTypeName == "" {
@@ -408,6 +416,10 @@ func (i *importer) queryImports(filename string) fileImports {
 	if uses("uuid.UUID") && !overrideUUID {
 		pkg[ImportSpec{Path: "github.com/google/uuid"}] = struct{}{}
 	}
+	_, overrideNullUUID := overrideTypes["uuid.NullUUID"]
+	if uses("uuid.NullUUID") && !overrideNullUUID {
+		pkg[ImportSpec{Path: "github.com/google/uuid"}] = struct{}{}
+	}
 
 	// Custom imports
 	for _, o := range i.Settings.Overrides {

internal/codegen/golang/postgresql_type.go

@@ -103,7 +103,10 @@ func postgresType(r *compiler.Result, col *compiler.Column, settings config.Comb
 		return "sql.NullString"
 
 	case "uuid":
-		return "uuid.UUID"
+		if notNull {
+			return "uuid.UUID"
+		}
+		return "uuid.NullUUID"
 
 	case "inet", "cidr":
 		return "net.IP"

internal/endtoend/testdata/go.mod

@@ -4,7 +4,7 @@ go 1.16
 
 require (
 	github.com/gofrs/uuid v4.0.0+incompatible
-	github.com/google/uuid v1.2.0
+	github.com/google/uuid v1.3.0
 	github.com/jackc/pgconn v1.5.1-0.20200601181101-fa742c524853
 	github.com/jackc/pgtype v1.6.2
 	github.com/jackc/pgx/v4 v4.6.1-0.20200606145419-4e5062306904

internal/endtoend/testdata/go.sum

@@ -16,6 +16,8 @@ github.com/gofrs/uuid v4.0.0+incompatible/go.mod h1:b2aQJv3Z4Fp6yNu3cdSllBxTCLRx
 github.com/google/renameio v0.1.0/go.mod h1:KWCgfxg9yswjAJkECMjeO8J8rahYeXnNhOm40UhjYkI=
 github.com/google/uuid v1.2.0 h1:qJYtXnJRWmpe7m/3XlyhrsLrEURqHRM2kxzoxXqyUDs=
 github.com/google/uuid v1.2.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/google/uuid v1.3.0 h1:t6JiXgmwXMjEs8VusXIJk2BXHsn+wx8BZdTaoZ5fu7I=
+github.com/google/uuid v1.3.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/jackc/chunkreader v1.0.0 h1:4s39bBR8ByfqH+DKm8rQA3E1LHZWB9XWcrz8fqaZbe0=
 github.com/jackc/chunkreader v1.0.0/go.mod h1:RT6O25fNZIuasFJRyZ4R/Y2BbhasbmZXF9QQ7T3kePo=
 github.com/jackc/chunkreader/v2 v2.0.0/go.mod h1:odVSm741yZoC3dpHEUXIqA9tQRhFrgOHwnPIn9lDKlk=

internal/endtoend/testdata/types_uuid/postgresql/stdlib/query.sql

@@ -0,0 +1,11 @@
+CREATE TABLE foo (
+    description text,
+    bar uuid,
+    baz uuid not null
+);
+
+-- name: List :many
+SELECT * FROM foo;
+
+-- name: Find :one
+SELECT bar FROM foo WHERE baz = $1;

internal/endtoend/testdata/types_uuid/postgresql/stdlib/sqlc.json

@@ -0,0 +1,11 @@
+{
+  "version": "1",
+  "packages": [
+    {
+      "path": "go",
+      "name": "querytest",
+      "schema": "query.sql",
+      "queries": "query.sql"
+    }
+  ]
+}