How to set values in lightning dual list box in lwc

Question

I need to populate my lightning-dual-listbox with the fields of selected object. My apex class returns the list of fields, I have fetched the values in this.objectFields but they are not getting populated in dual-listbox.

Apex class

   @AuraEnabled(cacheable=true)
    public static List<String> getObjectFields(String objectName){
        system.debug(objectName);
        SObjectType objectType = Schema.getGlobalDescribe().get((objectName));
        Map<String,Schema.SObjectField> mfields = objectType.getDescribe().fields.getMap();

        List<String> sObjectDetailsList = new List<String>();
        for(String s : mfields.keySet()){
            sObjectDetailsList.add(String.valueOf(mfields.get(s)));
        }
        return sObjectDetailsList;
    }

JS file

@track objectFields = [];
 getObjectFields({
            objectName: this.selectedObject
        })
        .then(result => {
            var fields = result;
            console.log('fields : '+fields);
            this.objectFields = fields;
            console.log('this.objectFields : '+this.objectFields);

        })
        .catch(error => {
            this.error = error;
            console.log('error ===>: ' + error.body.message);
        });

HTML File

<lightning-dual-listbox name="Fields"
                            label="Select Fields"
                            source-label="Available"
                            selected-label="Selected"
                            field-level-help="Select your preferred fields"
                            options={objectFields}
                            onchange={handleChange}></lightning-dual-listbox>

Answer 1

If you check the documenation, you might notice that each object in the array of options contains the following properties: label and value:

{ label: 'English', value: 'en' }

so, you should make sure that each of your results contains these in order to properly appear in the dual-listbox options.

Answer 2

Try store the using label, value format in objectFields, as below

@track objectFields = [];
 getObjectFields({
            objectName: this.selectedObject
        })
        .then(result => {
            result.forEach(element=> this.objectFields.push({
                value: element.value,
                label: element.value});
         })
        .catch(error => {
            this.error = error;
            console.log('error ===>: ' + error.body.message);
        });