Picker can not get column value when defaultIndex & defaultValue are not given

[xxyan0205]

Mand Mobile Version

v1.4.3

OS Version & Browser Version

all

Recurring Steps

    <md-picker
      ref="picker"
      :data="[[{text: 1}, {text:2}, {text:3}]]"
    ></md-picker>

    console.log(this.$refs.picker.getColumnValues())

Expectant Behaviors

[{text:1}]

Actual Behaviors

[undefined]