Call add_invoice when adding invoice from Go

I needed to add binary encoding function for the new_invoice_product
type, and currently it is not correct: i hardcoded the OID values, but
they are going to be different on a different database.

go.mod

@@ -10,6 +10,7 @@ require (
 )
 
 require (
+	github.com/jackc/pgio v1.0.0
 	github.com/jackc/pgtype v1.12.0
 	golang.org/x/crypto v0.0.0-20220829220503-c86fa9a7ed90 // indirect
 )

pkg/db.go

@@ -4,6 +4,8 @@ import (
 	"context"
 	"log"
 
+	"github.com/jackc/pgio"
+	"github.com/jackc/pgtype"
 	"github.com/jackc/pgx/v4"
 	"github.com/jackc/pgx/v4/pgxpool"
 )
@@ -12,6 +14,66 @@ type Db struct {
 	*pgxpool.Pool
 }
 
+type newInvoiceProductArray []*invoiceProductForm
+
+type discountRate struct {
+	pgtype.Numeric
+}
+
+func (form *invoiceProductForm) EncodeBinary(ci *pgtype.ConnInfo, buf []byte) (newBuff []byte, err error) {
+	productId := &pgtype.Int4{}
+	if err = productId.Set(form.ProductId.Val); err != nil {
+		return
+	}
+	name := &pgtype.Text{String: form.Name.Val, Status: pgtype.Present}
+	description := &pgtype.Text{String: form.Description.Val, Status: pgtype.Present}
+	price := &pgtype.Text{String: form.Price.Val, Status: pgtype.Present}
+	quantity := &pgtype.Int4{}
+	if err = quantity.Set(form.Quantity.Val); err != nil {
+		return
+	}
+	discount := &discountRate{}
+	if err = discount.Set(form.Discount.Val); err != nil {
+		return
+	}
+	tax := &pgtype.Int4Array{}
+	if err = tax.Set(form.Tax.Selected); err != nil {
+		return
+	}
+	ct := pgtype.CompositeFields{productId, name, description, price, quantity, discount, tax}
+	return ct.EncodeBinary(ci, buf)
+}
+
+func (src newInvoiceProductArray) EncodeBinary(ci *pgtype.ConnInfo, buf []byte) ([]byte, error) {
+	arrayHeader := pgtype.ArrayHeader{
+		Dimensions: []pgtype.ArrayDimension{{Length: int32(len(src)), LowerBound: 1}},
+	}
+
+	/*typeName := "numerus.new_invoice_product"
+	if dt, ok := ci.DataTypeForName(typeName); ok {
+		arrayHeader.ElementOID = int32(dt.OID)
+	} else {
+		return nil, fmt.Errorf("unable to find oid for type name %v", typeName)
+	}*/
+	arrayHeader.ElementOID = 69053
+	buf = arrayHeader.EncodeBinary(ci, buf)
+	for i := range src {
+		sp := len(buf)
+		buf = pgio.AppendInt32(buf, -1)
+
+		elemBuf, err := src[i].EncodeBinary(ci, buf)
+		if err != nil {
+			return nil, err
+		}
+		if elemBuf != nil {
+			buf = elemBuf
+			pgio.SetInt32(buf[sp:], int32(len(buf[sp:])-4))
+		}
+	}
+
+	return buf, nil
+}
+
 func NewDatabase(ctx context.Context, connString string) (*Db, error) {
 	config, err := pgxpool.ParseConfig(connString)
 	if err != nil {
@@ -20,6 +82,7 @@ func NewDatabase(ctx context.Context, connString string) (*Db, error) {
 
 	config.AfterConnect = func(ctx context.Context, conn *pgx.Conn) error {
 		_, err := conn.Exec(context.Background(), "SET search_path TO numerus, public")
+		conn.ConnInfo().RegisterDataType(pgtype.DataType{Value: &discountRate{}, Name: "discount_rate", OID: 69002})
 		return err
 	}
 

pkg/invoices.go

@@ -3,7 +3,6 @@ package pkg
 import (
 	"context"
 	"fmt"
-	"github.com/jackc/pgx/v4"
 	"github.com/julienschmidt/httprouter"
 	"html/template"
 	"math"
@@ -139,22 +138,7 @@ func HandleAddInvoice(w http.ResponseWriter, r *http.Request, _ httprouter.Param
 			mustRenderNewInvoiceForm(w, r, form)
 			return
 		}
-		tx := conn.MustBegin(r.Context())
-		invoiceId := tx.MustGetInteger(r.Context(), "insert into invoice (company_id, invoice_number, invoice_date, contact_id, notes, currency_code)  select company_id, $2, $3, $4, $5, currency_code from company join currency using (currency_code) where company_id = $1 returning invoice_id", company.Id, form.Number, form.Date, form.Customer, form.Notes)
-		batch := &pgx.Batch{}
-		for _, product := range form.Products {
-			batch.Queue("insert into invoice_product(invoice_id, product_id, name, description, price, quantity, discount_rate) select $2, $3, $4, $5, parse_price($6, decimal_digits), $7, $8 / 100::decimal from company join currency using (currency_code) where company_id = $1", company.Id, invoiceId, product.ProductId, product.Name, product.Description, product.Price, product.Quantity.Integer(), product.Discount.Integer())
-		}
-		br := tx.SendBatch(r.Context(), batch)
-		for range form.Products {
-			if _, err := br.Exec(); err != nil {
-				panic(err)
-			}
-		}
-		if err := br.Close(); err != nil {
-			panic(err)
-		}
-		tx.MustCommit(r.Context())
+		conn.MustExec(r.Context(), "select add_invoice($1, $2, $3, $4, $5, $6)", company.Id, form.Number, form.Date, form.Customer, form.Notes, newInvoiceProductArray(form.Products))
 		http.Redirect(w, r, companyURI(company, "/invoices"), http.StatusSeeOther)
 	default:
 		http.Error(w, gettext("Invalid action", locale), http.StatusBadRequest)