[elm-discuss] Encoding JSON and updating

[David Legard]

I am using a simple JSON decode and encode (following from examples at
elm-tutorial <https://www.elm-tutorial.org/en/>), but I'm clearly missing
something.

The *db.json* file has the simple structure

{
"plrs": {
"ixd": "FF",
"name": "Frank",
"level": 3
}
}


.. and I decode that successfully into an Elm object with an HTTP Get: from *http://localhost:3000/db.
*The Elm object holding the data has the type* Roster.*

When I encode it, and try to save it with an HTTP Send (to the identical
URL), I get a *File Not Found 404* error.

Do I need to tweak the URL for sending the data back, or would a mistake in
my Encoding code (quite a possibility) cause this to happen?

I'm running this as Administrator in case there are any permission issues.

I am using the code in the tutorial to create the HTTP request, as follows:

savePlayerRequest : Roster -> Http.Request Roster
savePlayerRequest roster =
Http.request
{ body = plrsEncoder roster |> Http.jsonBody
, expect = Http.expectJson plrsDecoder
, headers = []
, method = "PATCH"
, timeout = Nothing
, url = savePlayerUrl
, withCredentials = False
}

[David Andrews]

This depends on the backend server you are using and its configuration. It
has nothing to do with Elm.

I recommend against running your server as Administrator as a security
practice.


On Nov 19, 2017 2:05 AM, "David Legard" <***@gmail.com> wrote:

I am using a simple JSON decode and encode (following from examples at
elm-tutorial <https://www.elm-tutorial.org/en/>), but I'm clearly missing
something.

The *db.json* file has the simple structure

{
"plrs": {
"ixd": "FF",
"name": "Frank",
"level": 3
}
}


.. and I decode that successfully into an Elm object with an HTTP Get:
from *http://localhost:3000/db
<http://localhost:3000/db>. *The Elm object holding the data has the type*
Roster.*

When I encode it, and try to save it with an HTTP Send (to the identical
URL), I get a *File Not Found 404* error.

Do I need to tweak the URL for sending the data back, or would a mistake in
my Encoding code (quite a possibility) cause this to happen?

I'm running this as Administrator in case there are any permission issues.

I am using the code in the tutorial to create the HTTP request, as follows:

savePlayerRequest : Roster -> Http.Request Roster
savePlayerRequest roster =
Http.request
{ body = plrsEncoder roster |> Http.jsonBody
, expect = Http.expectJson plrsDecoder
, headers = []
, method = "PATCH"
, timeout = Nothing
, url = savePlayerUrl
, withCredentials = False
}
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[David Legard]

I'm testing it on *localhost*.

[Roman Frołow]

For uploading files I typically forward people
to https://github.com/simonh1000/file-reader/tree/master/example

[Steve Schafer]

The tutorial uses json-server, which, by default, expects PATCH requests to
go to a specific player's URL, not the top-level URL for all players. I
haven't played with the tutorial myself, so the following may not be 100%
accurate, but I think that you need to:

1. Give each player an ID field, and call that field "id".
2. When you perform the patch, the URL should be
http://localhost:3000/db/plrs/<id>. That is, the ID should be the final
part of the URL. (I'm not sure about the first part of the URL; your
example is not quite consistent with the json-server documentation.)

Post by David Legard
I'm testing it on *localhost*.

[Steve Schafer]

One other thing: You need to add a *Content-Type: application/json *header
to the request.

Post by David Legard
I'm testing it on *localhost*.

[David Legard]

OK, thanks for the suggestions.

There's something going on beyond my comprehension level.

I can read the data from http://localhost:3000/db, but when I try to send
it back, even with an Http.emptyBody, I get:

BadStatus { status = { code = 404, message = "Not Found" }, headers = Dict.fromList

[("Cache-Control","no-cache"),("Content-Type","application/json;
charset=utf-8"),("Expires","-1"),("Pragma","no-cache")], url =
"http://localhost:3000/db", body = "{}" }

[Steve Schafer]

Like I said in my previous message, you can't send data to that URL. That
URL identifies the *entire* database. With PUT, PATCH, and DELETE, you have
to use a URL that identifies a *specific *record in the database.

The error message also says that the body of the request is empty, but I
can't tell from the message itself what the underlying problem is with that.

Post by David Legard
OK, thanks for the suggestions.
There's something going on beyond my comprehension level.
I can read the data from http://localhost:3000/db, but when I try to send
BadStatus { status = { code = 404, message = "Not Found" }, headers = Dict

.fromList [("Cache-Control","no-cache"),("Content-Type","application/json;
charset=utf-8"),("Expires","-1"),("Pragma","no-cache")], url = "
http://localhost:3000/db", body = "{}" }

[David Legard]

OK, thanks, I didn't fully understand your previous message.

I'll do some more tinkering with this.