Handle dynamic parameters in URL in Golang

currently am working on an API Rest in Golang. I have the process to CRUD all the tables. Now someone is asking me to develop an endpoint to search in one of that tables based on the parameters send in the URL. Let's say that this is my struct for that table:

type Media struct {
	ID                         uint       
	Key                   string     
	RecordKey           string     
	RecordID            string     
	SystemMediaKey      string          
	MediaObjectID       string   
	ChangedByID         string   
	ChangedByKey        string   
	MediaCategory              string   
	MimeType                   string   
	ShortDescription           string   
	LongDescription            string   
	EntryTimestamp             time.Time
	ModificationTimestamp      time.Time  
	DeletedAtTimestamp         *time.Time 
	MediaModificationTimestamp time.Time
	MediaURL                   string   
	MediaHTML                  string   
	Order                      int      
	Group                      string   
	Width                      int      
	Height                     int      
	ImageSize                  string   
	ResourceName               string  
	ClassName                  string 
	Permission                 *string
	MediaStatus                string
}

Now, he can send me all or some of that fields in the URL, the I need to assign that values to my struct to be able to search in the database based on the data assigned to the object.

I am using Gorm to handle everything with the database, gorilla/schema to assign the values on the POST requests and the Julien Schmidt Router. Now,my questions are:

1. What should I configure in the route to accept dynamic parameters?
2. How can I assign the values that comes in the URL to the a type Media object?
   Thank you!

You could use the reflect package to iterate over the fields and set them by name. Be aware that the reflect package is arduous to use and comes with some dangers of panics if not used properly.

Also be aware that url.Values.Get only returns the first value (see https://godoc.org/net/url#Values.Get for details)

EDIT: I added code to account for the pointers in the struct. They are handled differently.

https://play.golang.org/p/AO4lYx7xka

package main
import (
"fmt"
"net/url"
"reflect"
"time"
)
type Media struct {
ID                         uint
Key                        string
RecordKey                  string
RecordID                   string
SystemMediaKey             string
MediaObjectID              string
ChangedByID                string
ChangedByKey               string
MediaCategory              string
MimeType                   string
ShortDescription           string
LongDescription            string
EntryTimestamp             time.Time
ModificationTimestamp      time.Time
DeletedAtTimestamp         *time.Time
MediaModificationTimestamp time.Time
MediaURL                   string
MediaHTML                  string
Order                      int
Group                      string
Width                      int
Height                     int
ImageSize                  string
ResourceName               string
ClassName                  string
Permission                 *string
MediaStatus                string
}
func main() {
testUrl := "www.example.com/test?MimeType=themimetype&Key=thekey&Permission=admin"
u, err := url.Parse(testUrl)
if err != nil {
fmt.Println(err)
return
}
params := u.Query()
media := &Media{}
val := reflect.ValueOf(media)
for i := 0; i < val.Elem().NumField(); i++ {
// get the reflect.StructField so we can get the Name
f := val.Elem().Type().Field(i)
// check if URL.Values contains the field
if v := params.Get(f.Name); v != "" {
// get the reflect.Value associated with the Field
field := val.Elem().FieldByName(f.Name)
kind := field.Kind()
// you must switch for each reflect.Kind (associated with the type in your struct)
// so you know which Set... method to call
switch kind {
case reflect.String:
field.SetString(v)
case reflect.Ptr:
// pointers are a special case that must be handled manually unfortunately.
// because they default to nil, calling Elem() won't reveal the underlying type
// so you must simply string match the struct values that are pointers.
switch f.Name {
case "Permission":
newVal := reflect.New(reflect.TypeOf(v))
newVal.Elem().SetString(v)
field.Set(newVal.Elem().Addr())
case "DeletedAtTimestamp":
}
}
}
}
fmt.Printf("%#v\n", media)
fmt.Println(*media.Permission)
}

I finally managed to use this library that converts a map to a struct. The only thing, is that I had to pre-process the map that is returned by URL.Query() Values because it returns an array for each value and I needed only the value and not inside an array.