How to check if a JSON key exists?
JSONObject class has a method named "has":
http://developer.android.com/reference/org/json/JSONObject.html#has(java.lang.String)
Returns true if this object has a mapping for name. The mapping may be NULL.
How to check if a key exists in Json Object and get its value
Use below code to find key is exist or not in JsonObject
. has("key")
method is used to find keys in JsonObject
.
containerObject = new JSONObject(container);
//has method
if (containerObject.has("video")) {
//get Value of video
String video = containerObject.optString("video");
}
If you are using optString("key")
method to get String value then don't worry about keys are existing or not in the JsonObject
.
Check if key exists in a json array
You can use a simple null check on the json fields using the ??
operator with a default. Use it like
productName: json["productName"] ?? 'Default Product Name';
That should automatically set the default value Default Product Name
if the JSON field is null.
It's essentially a short hand for
productName: json["productName"] != null ? json["productName"] : 'Default Product Name';
How to check key exist in json or not
var json = {key1: 'value1', key2: 'value2'}
"key1" in json ? console.log('key exists') : console.log('unknown key')
"key3" in json ? console.log('key exists') : console.log('unknown key')
how to find if key value pair exists in json object using switch statement
In addition to the answer from Fiouze, you can also do these:
// will return true if the property exists.
'city' in x.address
// will return a value if set or undefined if not.
x.address.city
But if you want to stick with the switch case, you can iterate through the properties by doing something like:
for (const prop in x.address) {
switch (prop) {
case 'city':
return x.address.city;
case 'village':
return x.address.village;
default:
alert('err');
}
}
Reference: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...in
How to check for a particular key exists in json string or not
You can parse JSON string within a Script component using JavaSerializer or JSON.Net assemblies and search for the key value.
- Importing JSON Files Using SQL Server Integration Services
- newtonsoft json package requires reinstall every time i open code
If the JSON data is formal and contains only keys and values then you can search for the following string "-1":
, if it is found then the -1
key is found.
if(json.contains("\"-1\":")){
//key found
}else{
// key not found
}
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