I'm using std.json for parsing json. I need to check if a specific string key is in JSONValue.object. The first thing I tried was:

JSONValue root = parseJSON(text);
if(root["key"].isNull == false) {
    //do stuff with root["key"]
}

But that code doesn't work, because calling root["key"] will throw an exception of key not fount if "key" isn't there.

I need some method `root.contains("key")` method to check if the object has a key.

Thanks in advance!

On Tue, Oct 06, 2015 at 08:28:46PM +0000, Borislav Kosharov via Digitalmars-d-learn wrote:
> JSONValue root = parseJSON(text);
> if(root["key"].isNull == false) {

try

if("key" in root) {
	// it is there
} else {
	// it is not there
}


you can also do

if("key" !in root) {}

On Tuesday, 6 October 2015 at 20:44:30 UTC, via Digitalmars-d-learn wrote:
> On Tue, Oct 06, 2015 at 08:28:46PM +0000, Borislav Kosharov via Digitalmars-d-learn wrote:
>> JSONValue root = parseJSON(text);
>> if(root["key"].isNull == false) {
>
> try
>
> if("key" in root) {
> 	// it is there
> } else {
> 	// it is not there
> }
>
>
> you can also do
>
> if("key" !in root) {}

Additionally, just like associative arrays, if you need to access the value, you can get a pointer to it with the in operator (and if the key doesn't exist, it will return a null pointer).

const(JSONValue)* p = "key" in root;
if (p)
{
    // key exists, do something with p or *p
}
else
{
    // key does not exist
}

Am Tue, 06 Oct 2015 21:39:28 +0000
schrieb Fusxfaranto <fusxfaranto@gmail.com>:

> Additionally, just like associative arrays, if you need to access the value, you can get a pointer to it with the in operator (and if the key doesn't exist, it will return a null pointer).
> 
> const(JSONValue)* p = "key" in root;
> if (p)
> {
>      // key exists, do something with p or *p
> }
> else
> {
>      // key does not exist
> }

And you could go further and write

if (auto p = "key" in root)
{
     // key exists, do something with p or *p
}
else
{
     // key does not exist
}

-- 
Marco

Thanks guys that was I was looking for!