Compatible way to enhance context.Param(), supportted from GET POST COOKIE Route/Var

[xiuno]

Compatible way to enhance context.Param(), support fetch data from Route:key, _GET, _POST, _COOKIE.

In some nodejs frameworks, such as express koa, we can easily use param to get parameters of different ways(GET POST COOKIE...). Considering Gin's design principles, I feel a little wasteful for param to only get parameters on the route. So we can get the parameters conveniently.

Before I got the int in POST, I thought it was not convenient to have a mandatory conversion or bind to display.

Before:

age, err: = strconv.Atoi (ctx.PostForm ("age"))
if err! = nil {
    age = 0
}

Now:

age: = ctx.ParamInt ("age")

[codecov]

Codecov Report

Merging #1627 into master will increase coverage by 0.25%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1627      +/-   ##
==========================================
+ Coverage   99.28%   99.53%   +0.25%     
==========================================
  Files          40       22      -18     
  Lines        1958      431    -1527     
==========================================
- Hits         1944      429    -1515     
+ Misses         10        1       -9     
+ Partials        4        1       -3

Impacted Files	Coverage Δ
logger.go
debug.go
tree.go
utils.go
response_writer.go
fs.go
response_writer_1.8.go
path.go
context_17.go
auth.go
... and 7 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 66b47a8...45cf4f0. Read the comment docs.

[thinkerou]

you should have one utils package, like:

package utils 

func StringToInt(s string) (i int) {
	i, err := strconv.Atoi(s)
	if err != nil {
		return 0
	} else {
		return i
	}
}

and like the follow use it:

utils.StringToInt(ctx.PostForm ("age"))

I think framework should not have these functions, it should keep simple. do you think?
cc @appleboy

[thoeni]

I don't think this is strictly needed as you can just have these conversions in your application, it doesn't belong to Gin, I guess?

[thoeni]

This could be:

func StringToInt(s string) (i int) {
	i, _ = strconv.Atoi(s)
	return
}

or even better:

func StringToInt(s string) int {
	i, _ := strconv.Atoi(s)
	return i
}

as you shouldn't use named returns...

[appleboy]

move internal package to top.

[appleboy]

if v := c.Query(key); v != "" {
	return v
}

if v := c. PostForm(key); v != "" {
	return v
}

...

[zdpdpdp]

i support this.

In gin framework , we can see these functions of *context like below

// GetStringSlice returns the value associated with the key as a slice of strings.
func (c *Context) GetStringSlice(key string) (ss []string) {
      //
}

// GetStringMap returns the value associated with the key as a map of interfaces.
func (c *Context) GetStringMap(key string) (sm map[string]interface{}) {
	//
}

these also can use utils function to convert, but gin support convenient functions to call

so why not support a high call frequency function like ctx.ParamInt()?

cc @thinkerou