How to check if array of object is empty?

Question

I want to check if the array of objects is empty or not, I'm storing the result from API call in state city_name.

cities = this.state.city_name;
console.warn(cities); //this return an empty array []
cities === null ? console.log(cities) : ToastAndroid.showWithGravity('No Result 
                                                                      Found',ToastAndroid.LONG)

I keep getting an error double java.lang.Double.doubleValue() on a null object. even tried cities.length == 0 and (this.state.city_name).lenght == 0 it return the same error.

This is the data from API call:

city_name = [{"country_flag_url": "https://b.zmtcdn.com/images/countries/flags/country_216.png", "country_id": 216, "country_name": "United States", "discovery_enabled": 1, "has_go_out_tab": 0, "has_new_ad_format": 0, "id": 11282, "is_state": 0, "name": "Del Aire, CA", "should_experiment_with": 0, "state_code": "CA", "state_id": 73, "state_name": "California"}, {"country_flag_url": "https://b.zmtcdn.com/images/countries/flags/country_216.png", "country_id": 216, "country_name": "United States", "discovery_enabled": 0, "has_go_out_tab": 0, "has_new_ad_format": 0, "id": 4463, "is_state": 0, "name": "Del Norte, CO", "should_experiment_with": 0, "state_code": "CO", "state_id": 74, "state_name": "Colorado"}, {"country_flag_url": "https://b.zmtcdn.com/images/countries/flags/country_216.png", "country_id": 216, "country_name": "United States", "discovery_enabled": 0, "has_go_out_tab": 0, "has_new_ad_format": 0, "id": 9431, "is_state": 0, "name": "Del Rio, TX", "should_experiment_with": 0, "state_code": "TX", "state_id": 111, "state_name": "Texas"}]

Please help me

An empty array is not considered to be null. An empty array is still an array. Don't use the ternary operator here if you're doing console.log(cities), instead use a simple if statement to check the following: if (cities.length === 0) { ToastAndroid.showWithGravity(...) }. — goto
– goto, Commented Mar 2, 2020 at 13:32

user12551649 · Accepted Answer · 2020-03-02 15:26:47Z

2

You can do something like this

 cities = this.state.city_name;
 
 arr = cities.length;
 
 if(arr == 0) {
     console.log('no result found')
       }
 
 else {
     console.log(cities)
       }

edited Mar 2, 2020 at 15:26

user12551649

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answered Mar 2, 2020 at 13:43

Efraim Jerszurki

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2 Comments

goto Over a year ago

It should be length not lenght.

Efraim Jerszurki Over a year ago

sorry for the typo, it is length indeed

Amit · Accepted Answer · 2020-03-02 13:37:33Z

2

Check for the length of the array and then try to do your task.

if(cities.length)
// do your task here
else
// handle here

answered Mar 2, 2020 at 13:37

Amit

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Comments

JayDJohno · Accepted Answer · 2020-03-02 13:41:47Z

0

I think the issue may be that you are using === which is strict and you will get the error on a double element. Null is a string and double is a number.

if(cities != null && cities.length>0){
    //not empty, do something with data
}else
    //array is empty, so add values.

answered Mar 2, 2020 at 13:41

JayDJohno

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1 Comment

cthmsst Over a year ago

if( cities && cities.length>0 ) to properly handle undefined too

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