• Andrea Fontana (14/14) Jan 22 2016 If you declare a JSONValue like this:
• userABCabc123 (14/28) Jan 22 2016 read this:
• Andrea Fontana (2/13) Jan 22 2016 That's right, but I need an empty object, without any key set!
• userABCabc123 (6/21) Jan 22 2016 But soon or later you'll need to add values to your object so
• Andrea Fontana (4/7) Jan 22 2016 You're wrong, I need an empty object for an API call!
• userABCabc123 (6/13) Jan 22 2016 It's true that it can be problematic, for example with an input
• Chris Wright (5/11) Jan 22 2016 Which works out to one way that actually has the behavior that Andrea
• Borislav Kosharov (7/21) Jan 22 2016 What you can do is use the JSONValue ctor and pass it an empty

Andrea Fontana <nospam example.com> writes:

If you declare a JSONValue like this:

JSONValue json;

then:

assert(json.type() == JSON_TYPE.NULL);

Documentation at 
https://dlang.org/phobos/std_json.html#.JSONValue.type.2 suggests 
not to change type but to assign a new value instead.

My problem is: how can I assign an empty object like {}?

The only way i found is using that deprecated method:
json.type = JSON_TYPE.OBJECT;

or

json = `{}`.parseJSON;

Please notice that to init as array this works:
json = JSONValue[].init;

userABCabc123 <userABCabc123 skdhf.ri> writes:

On Friday, 22 January 2016 at 11:53:11 UTC, Andrea Fontana wrote:
 If you declare a JSONValue like this:

 JSONValue json;

 then:

 assert(json.type() == JSON_TYPE.NULL);

 Documentation at 
 https://dlang.org/phobos/std_json.html#.JSONValue.type.2 
 suggests not to change type but to assign a new value instead.

 My problem is: how can I assign an empty object like {}?

 The only way i found is using that deprecated method:
 json.type = JSON_TYPE.OBJECT;

 or

 json = `{}`.parseJSON;

 Please notice that to init as array this works:
 json = JSONValue[].init;

read this:

https://issues.dlang.org/show_bug.cgi?id=15410

when you add the first key, the value will be set to 
JSON_TYPE.OBJECT

----
import std.json;

void main(string[] args)
{
     JSONValue json;
     json["first"] = 0;
     assert(json.type == JSON_TYPE.OBJECT);
}
----

Andrea Fontana <nospam example.com> writes:

On Friday, 22 January 2016 at 12:05:48 UTC, userABCabc123 wrote:
 when you add the first key, the value will be set to 
 JSON_TYPE.OBJECT

 ----
 import std.json;

 void main(string[] args)
 {
     JSONValue json;
     json["first"] = 0;
     assert(json.type == JSON_TYPE.OBJECT);
 }
 ----

That's right, but I need an empty object, without any key set!

userABCabc123 <userABCabc123 skdf.gz> writes:

On Friday, 22 January 2016 at 12:54:38 UTC, Andrea Fontana wrote:
 On Friday, 22 January 2016 at 12:05:48 UTC, userABCabc123 wrote:
 when you add the first key, the value will be set to 
 JSON_TYPE.OBJECT

 ----
 import std.json;

 void main(string[] args)
 {
     JSONValue json;
     json["first"] = 0;
     assert(json.type == JSON_TYPE.OBJECT);
 }
 ----

 That's right, but I need an empty object, without any key set!

But soon or later you'll need to add values to your object so 
just imagine it's already an object, even if it will only become 
one when you'll start to add some values.

I don't really get your problem here, as in the first message you 
also start with an empty json.

Andrea Fontana <nospam example.com> writes:

On Friday, 22 January 2016 at 16:45:22 UTC, userABCabc123 wrote:
 But soon or later you'll need to add values to your object so 
 just imagine it's already an object, even if it will only 
 become one when you'll start to add some values.

You're wrong, I need an empty object for an API call!

Moreover "{}" it's a valid json object and there's no easy way to 
create it using std.json.

userABCabc123 <userABCabc123 skdf.gz> writes:

On Friday, 22 January 2016 at 16:58:51 UTC, Andrea Fontana wrote:
 On Friday, 22 January 2016 at 16:45:22 UTC, userABCabc123 wrote:
 But soon or later you'll need to add values to your object so 
 just imagine it's already an object, even if it will only 
 become one when you'll start to add some values.

 You're wrong, I need an empty object for an API call!

 Moreover "{}" it's a valid json object and there's no easy way 
 to create it using std.json.

It's true that it can be problematic, for example with an input 
contract, or for subtyping a JSONValue as something like struct 
JSONValueThatAlwayObject{}...

But there is only 3 ways in std.json, from a literal, using the 
deprecated way or the "lazy" way.

Chris Wright <dhasenan gmail.com> writes:

On Fri, 22 Jan 2016 17:34:58 +0000, userABCabc123 wrote:
 It's true that it can be problematic, for example with an input
 contract, or for subtyping a JSONValue as something like struct
 JSONValueThatAlwayObject{}...
 
 But there is only 3 ways in std.json, from a literal, using the
 deprecated way or the "lazy" way.

Which works out to one way that actually has the behavior that Andrea 
needs, and that involves parsing javascript. That's not ideal.

Vibe.d has a static method 'emptyObject' that returns a new empty object. 
That would be handy here.

Borislav Kosharov <boby_dsm abv.bg> writes:

On Friday, 22 January 2016 at 11:53:11 UTC, Andrea Fontana wrote:
 If you declare a JSONValue like this:

 JSONValue json;

 then:

 assert(json.type() == JSON_TYPE.NULL);

 Documentation at 
 https://dlang.org/phobos/std_json.html#.JSONValue.type.2 
 suggests not to change type but to assign a new value instead.

 My problem is: how can I assign an empty object like {}?

 The only way i found is using that deprecated method:
 json.type = JSON_TYPE.OBJECT;

 or

 json = `{}`.parseJSON;

 Please notice that to init as array this works:
 json = JSONValue[].init;

What you can do is use the JSONValue ctor and pass it an empty 
associative array

     auto json = JSONValue(string[string].init); //or 
JSONValue((JSONValue[string]).init)

It's a little verbose but gets the job done without using 
deprecated things or parseJSON