# Using from\_json method of a class with a post request
**URL:** https://forum.crystal-lang.org/t/using-from-json-method-of-a-class-with-a-post-request/1015
**Category:** Help & Support
**Created:** [July 31, 2019, 2:29pm UTC](https://forum.crystal-lang.org/t/using-from-json-method-of-a-class-with-a-post-request/1015 "2019-07-31T14:29:57Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@curious2learn](https://forum.crystal-lang.org/u/curious2learn)
#### Post date: [July 31, 2019, 2:29pm UTC](https://forum.crystal-lang.org/t/using-from-json-method-of-a-class-with-a-post-request/1015/1 "2019-07-31T14:29:57Z")
Sorry in advance for not including a working example. Hoping if someone is aware of the issue and can answer without a working example.
I have a struct, say
```
struct User
JSON.mapping(
name: String?,
email: String,
hobbies: Array(String)?
)
end
```
I make a json post request from the client to the server (a route in Kemal) that contains the user’s information. Option 1 below fails, while option 2 works. Any ideas why Option 1 is failing? Why do I have to do `JSON.parse(postbody).to_json` for it to work. I am worried that the solution may not be robust. Would really appreciate any help.
**Option 1 (errors out with: _Unexpected token: EOF at 1:1_)**
```
postbody = env.request.body.not_nil!
user = User.from_json(postbody)
```
**Option 2 (this works)**
```
postbody = env.request.body.not_nil!
modpostbody = JSON.parse(postbody).to_json
user = User.from_json(postbody)
```
Thank you.
---
### Author:  [@asterite](https://forum.crystal-lang.org/u/asterite)
#### Post date: [July 31, 2019, 4:44pm UTC](https://forum.crystal-lang.org/t/using-from-json-method-of-a-class-with-a-post-request/1015/2 "2019-07-31T16:44:16Z")
What’s the post request body?
---
### Author:  [@curious2learn](https://forum.crystal-lang.org/u/curious2learn)
#### Post date: [July 31, 2019, 4:54pm UTC](https://forum.crystal-lang.org/t/using-from-json-method-of-a-class-with-a-post-request/1015/3 "2019-07-31T16:54:27Z")
Hi @asterite,
The post request body is supposed to be a json body containing the user object (I am using Elm on the frontend to create the json).
So it looks like
`{"name": "Crystal", "email": "crystal@example.com", "hobbies": ["fast", "fun", "resourceful"}`
This is the output in the terminal when I invoke `puts JSON.parse(postbody)` (which works):
{“name” =\> “Crystal”, “email” =\> "crystal@example.com", “hobbies” =\> [“fast”, “fun”, “resourceful”]}
---
### Author:  [@asterite](https://forum.crystal-lang.org/u/asterite)
#### Post date: [July 31, 2019, 5:11pm UTC](https://forum.crystal-lang.org/t/using-from-json-method-of-a-class-with-a-post-request/1015/4 "2019-07-31T17:11:26Z")
I can’t reproduce the problem using HTTP::Server.
Could you provide the full code? Like runnable code that I can download, just do `crystal some_file.cr` and then provide the `curl` line or whatever method you are feeding data to the server?
---
### Author:  [@curious2learn](https://forum.crystal-lang.org/u/curious2learn)
#### Post date: [July 31, 2019, 6:34pm UTC](https://forum.crystal-lang.org/t/using-from-json-method-of-a-class-with-a-post-request/1015/5 "2019-07-31T18:34:44Z")
Thank you @asterite. I will try to make a runnable version and post it.
---
### Author:  [@curious2learn](https://forum.crystal-lang.org/u/curious2learn)
#### Post date: [August 2, 2019, 3:01pm UTC](https://forum.crystal-lang.org/t/using-from-json-method-of-a-class-with-a-post-request/1015/6 "2019-08-02T15:01:07Z")
Hi @asterite
Sorry for not posting a runnable version yet. But I wanted to point out that I figured out the issue (it was my mistake). I think the problem was that I was actually doing the following to check the post request.
```
postbody = env.request.body.not_nil!
puts JSON.parse(postbody) ## this empties the postbody
user = User.from_json(postbody) ##Now that the postbody is empty, I get EOF error
```
Wouldn’t it be better to copy the postbody when passed to a function like this, so that this does not occur inadvertently? Probably it is not very efficient.
Thanks.