model: Use only string types for models

When a HTML form is converted to JSON by JavaScript using `FormData()`,
`Object.fromEntries()` and `JSON.stringify` the data type is always
`string`. This does not match the Go struct definitions using multiple
types including e.g. `int`.

There are several options to solve this conflict:

1. use only strings in Go struct definitions
2. write custom functions to parse string-based JSONs to Go structs
3. implement custom functions in JS to use `number` type if possible

Option 3 seems to be a very clean solution. Nevertheless it is limited
by the fact that JSON anyway has a way more limited type system than Go.
So the types used in Go cannot be used and this would reduce this option
to a variant of option 2.

Option 2 requires significant effort per struct inside the model
package. Every object which is transferred via JSON and serialized into
Go structs would require a second struct definition with string types
and a conversion function. This does not scale.

Thus option 1 seems to be the best fit. The reasons for using types like
`int` or `bool` are:

- less memory consumption than `string` in most cases
- implicit data validation (e.g. enforcing positive numbers with `uint`)
- better compatibility with certain APIs which rely on e.g. `int`

The first argument is not so relevant in this use case. The amount of
required memory is still quite small for servers. Implicit data
validation is a good thing but not enough. There should anyway be
validation method which has to be called on CRUD methods and JSON
deserialization.

1 files changed, 9 insertions, 7 deletions

diff --git a/model/recipe.go b/model/recipe.go
index 1510379..e5cf0a6 100644
--- a/model/recipe.go
+++ b/model/recipe.go
@@ -3,23 +3,24 @@ package model
 import (
 	"database/sql"
 	"errors"
+	"fmt"
 	"time"
 )
 
 type Recipe struct {
-	Id          int64  `json:"id"`
+	Id          string `json:"id"`
 	Title       string `json:"title"`
-	Portions    int    `json:"portions"`
+	Portions    string `json:"portions"`
 	Url         string `json:"url"`
 	Notes       string `json:"notes"`
-	Created     int64  `json:"created"`
-	LastChanged int64  `json:"last_changed"`
+	Created     string `json:"created"`
+	LastChanged string `json:"last_changed"`
 }
 
 func (r *Recipe) Create() error {
 	now := time.Now().Unix()
-	r.Created = now
-	r.LastChanged = now
+	r.Created = fmt.Sprint(now)
+	r.LastChanged = r.Created
 
 	query := `INSERT INTO recipes
     (title, portions, url, notes, created, last_changed)
@@ -32,10 +33,11 @@ VALUES
 		return err
 	}
 
-	r.Id, err = result.LastInsertId()
+	id, err := result.LastInsertId()
 	if err != nil {
 		return err
 	}
+	r.Id = fmt.Sprint(id)
 
 	return nil
 }