Check If a Key Exists Inside a Json Object

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.

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

Use any() to check if certain key exists in JQ

Provide any with an iterator and a condition

jq 'any(paths; .[-1] == "headline")'

You can also provide the -e (or --exit-status) option to have an exit status of 0 if the result was true, and 1 if the result was false, which can immediately be used for further processing in the shell.

jq -e 'any(paths; .[-1] == "headline")'

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.

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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

} 

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 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 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')