Magento 2 backend configuration field with custom source model not working

Question

I am trying to add a new configuration field to my module's configuration page that uses a custom source_model, as soon as I add the field to system.xml the whole configuration section goes blank. If I take out the field, the section works fine and shows other fields as expected.

//file app/code/TahirYasin/Hello/etc/adminhtml/system.xml

...
                <field id="custom_select" 
                    translate="label" 
                    type="select" 
                    sortOrder="2" 
                    showInDefault="1" 
                    showInWebsite="1" 
                    showInStore="1">
                    <label>Scope</label>
                    <source_model>TahirYasin\Hello\Model\Config\Source\Custom</source_model>
                </field>
...

my new source model

//file app/code/TahirYasin/Hello/Model/Config/Source/Custom.php

<?php

namespace TahirYasin\Hello\Model\Config\Source;

class Custom implements \Magento\Framework\Option\ArrayInterface
{ 
    /**
     * Return array of options as value-label pairs, eg. value => label
     *
     * @return array
     */
    public function toOptionArray()
    {
        return [
            'value' => 'Label',
            'another_value' => 'Another value',
        ];
    }
}

What am I doing wrong here? Any help plz

Answer 1

public function toOptionArray()
{
    return [
        ['value' => 'val1', 'label' => __('Label 1')],
        ['value' => 'val2', 'label' => __('Label 2')]
    ];
}

Add options to the arrays

Answer 2

Your class name in the source_model is not the same like the class name. Has to be

<source_model>TahirYasin/Hello/Model/Config/Source/Custom</source_model>

Answer 3

Hello I have perfect solution which will work 100 % ., You have to define only in system.xml .

<backend_model>Magento\Contact\Model\System\Config\Backend\Links</backend_model>

If you have any query let me know .