ElementUI Error in callback for watcher “data”: “Error: [ElTable] prop row-key is required”

Error in callback for watcher “data”: “Error: [ElTable] prop row-key is required”
Error: [ElTable] prop row-key is required

<el-table 
    :data="props.row.Entities" 
    border size="mini" 
    :row-key="getRowKeys" 
    empty-text="No node design relationship at this time">
    <el-table-column type="selection" :reserve-selection="true" width="55"></el-table-column>
    <el-table-column prop="phone" label="Affiliation" ></el-table-column>
    <el-table-column prop="nickName" label="Model Name" ></el-table-column>
</el-table>

JS

getRowKeys(row) {
    return row.staffTypeId;
},

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