Set the keyField for CRUD Operations

I use the WebApiAdaptor for remote data source. I also want to use the CommandColumn Option to delete the entries.

The issue now is, that the keyField is undefined in the remove function. So I receive urls like `http://example.com/user/undefined` . How do I set the correct key? In my case the key has the name hash and is not displayed in the grid, but is available in the source. I tried to define the key element in the Datamanager section, but I guess it's the wrong part.

<ejs-grid ref='grid' :data-source="gridSource" :allow-paging="true"
          >
    <e-columns>
        <e-column type='checkbox' width='50'>e-column>
        <e-column field='firstname' header-text='Filename' width=90 :template="userTemplate">e-column>
        <e-column field='account_created' header-text='Created at' width=90>e-column>
        <e-column headerText='Manage Records' width='160' :commands='commands'>e-column>
    e-columns>
ejs-grid>


data() {
    return {

        gridSource: new DataManager({
            url: '/user',
            adaptor: new WebApiAdaptor({
                
            }),
            key: 'hash'
        }),
        commands: [
            { type: 'Delete', buttonOption: { iconCss: 'e-icons e-delete', cssClass: 'e-flat' } },
        ],
}}

Thanks in advance