I have this String an I covered it to jsonNode using the ObjectMapper. Then I tried to look for a pecific key in this jsonNode so I used the ".has" but it did not work:! Here is what I did :
{
"links": {
"data": {
"self": {
"body": "",
"content_type": "",
"href": "/api/v2/nodes",
"method": "POST",
"name": ""
}
}
},
"results": {
"data": {
"properties": {
"container": true,
"container_size": 0,
"create_date": "2020-06-22T16:19:07",
"create_user_id": 1000,
"description": ""
"description_multilingual": {
"en": "",
"fr_FR": ""
},
"external_create_date": null,
"external_identity": "",
"external_identity_type": "",
"external_modify_date": null,
"external_source": "",
"favorite": false,
"id": 276625,
"mime_type": null,
"modify_date": "2020-06-22T16:19:07",
"modify_user_id": 1000,
"name": "mar",
"name_multilingual": {
"en": "mar",
"fr_FR": ""
},
"owner": "Admin",
"owner_group_id": 1001,
"owner_user_id": 1000,
"parent_id": 2000,
"permissions_model": "advanced",
"reserved": false,
"reserved_date": null,
"reserved_shared_collaboration": false,
"reserved_user_id": 0,
"size": 0,
"size_formatted": "0 Eléments",
"type": 0,
"type_name": "Dossier",
"versions_control_advanced": false,
"volume_id": -2000
}
}
}
}
and I want to test whether it has the "id" key (it actually exists in line 31) so I used .has()
as mentioned in How to check if a json key exists? :
ObjectMapper mapper = new ObjectMapper();
JsonNode rootNode= mapper.readTree(body);
if(rootNode.has("id")){
System.out.println(true);
}
else{
System.out.println(false);
}
but always it shows me "false" as output !!
If you're trying to find a key which is placed inside nested object, you may use findValue(String key)
method which returns null if a value is not found by the given key:
ObjectMapper mapper = new ObjectMapper();
JsonNode rootNode= mapper.readTree(json);
String[] keys = {
"id", "create_date", "versions_control_advanced", "name", "nofield"
};
for (String key : keys) {
JsonNode value = rootNode.findValue(key);
System.out.printf("Key %s exists? %s --> value=%s%n", key, value != null,
value == null ? null : value.asText());
}
Output:
Key id exists? true --> value=276625
Key create_date exists? true --> value=2020-06-22T16:19:07
Key versions_control_advanced exists? true --> value=false
Key name exists? true --> value=
Key nofield exists? false --> value=null
I think you are not bound to the has() method.
You can convert the json to a map and then find the node recursively
ObjectMapper mapper = new ObjectMapper();
Map<String, Object> map = mapper.readValue( body, Map.class );
ArrayList<Object> container = new ArrayList<>();
boolean value = find( map, "id", container );
if( value )
{
System.out.println( container );
}
The recursive method should visit all the nodes and return soon as node is found
private static boolean find( Map<String, Object> map, String search, ArrayList<Object> container )
{
int i = 0;
for( String s : map.keySet() )
{
i++;
if( s.equals( search ) )
{
container.add( map.get( s ) );
return true;
}
if( map.get( s ) instanceof Map )
{
boolean found = find( (Map<String, Object>) map.get( s ), search, container );
if( i == map.size() || found )
{
return found;
}
}
}
return false;
}
I have edited the code to get the value also. hope this helps. I strongly suggest you to do more research on yourself before looking for help from the community.
I'm a bit late to the party but i've just had a similar requirement. For checking if JsonNode has a Value one could do as well:
...
var dataO = data.AsObject();
// check for presence and value
if (dataO.Where(w => w.Key == "Mandatory" && w.Value == null).ToList().Count > 0)
{
...
whereas data is the JsonNode Object...
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.