Handle circular required keys

Use a dummy-value at first and update it later.
Deferrable doesn't seem to work for NOT NULL - only
for FOREIGN KEYs.

http/transaction.go

@@ -1,6 +1,7 @@
 package http
 
 import (
+	"fmt"
 	"net/http"
 	"time"
 
@@ -10,45 +11,50 @@ import (
 )
 
 func (h *Handler) newTransaction(c *gin.Context) {
-	transactionMemo, succ := c.GetPostForm("memo")
-	if !succ {
-		c.AbortWithStatus(http.StatusNotAcceptable)
-		return
-	}
-
+	transactionMemo, _ := c.GetPostForm("memo")
 	transactionAccount, succ := c.GetPostForm("account_id")
 	if !succ {
-		c.AbortWithStatus(http.StatusNotAcceptable)
+		c.AbortWithError(http.StatusNotAcceptable, fmt.Errorf("account_id missing"))
 		return
 	}
 
 	transactionAccountID, err := uuid.Parse(transactionAccount)
 	if !succ {
-		c.AbortWithStatus(http.StatusNotAcceptable)
+		c.AbortWithError(http.StatusNotAcceptable, fmt.Errorf("account_id is not a valid uuid"))
 		return
 	}
 
 	transactionDate, succ := c.GetPostForm("date")
 	if !succ {
-		c.AbortWithStatus(http.StatusNotAcceptable)
+		c.AbortWithError(http.StatusNotAcceptable, fmt.Errorf("date missing"))
 		return
 	}
 
 	transactionDateValue, err := time.Parse("2006-01-02", transactionDate)
 	if err != nil {
-		c.AbortWithStatus(http.StatusNotAcceptable)
+		c.AbortWithError(http.StatusNotAcceptable, fmt.Errorf("date is not a valid date"))
 		return
 	}
 
+	transactionAmount, succ := c.GetPostForm("amount")
+	if !succ {
+		c.AbortWithError(http.StatusNotAcceptable, fmt.Errorf("amount missing"))
+		return
+	}
+
+	amount := postgres.Numeric{}
+	amount.Set(transactionAmount)
 	new := postgres.CreateTransactionParams{
-		Memo:      transactionMemo,
-		Date:      transactionDateValue,
-		Amount:    postgres.Numeric{},
-		AccountID: transactionAccountID,
+		Memo:       transactionMemo,
+		Date:       transactionDateValue,
+		Amount:     amount,
+		AccountID:  transactionAccountID,
+		PayeeID:    uuid.NullUUID{},
+		CategoryID: uuid.NullUUID{},
 	}
 	_, err = h.Service.CreateTransaction(c.Request.Context(), new)
 	if err != nil {
-		c.AbortWithError(http.StatusInternalServerError, err)
+		c.AbortWithError(http.StatusInternalServerError, fmt.Errorf("create transaction: %w", err))
 		return
 	}
 }