調用子組件中的方法，明明定義了還報“Cannot read properties of undefined (reading 'fullValidEvent')”

在修改頁面，在父組件中直接調用子組件中的方法，通過ref來調用。明明在子組件中定義了這個方法，還一直報undefined

if (this.form.receivingType == 0) {
          await this.$refs.editTable1.fullValidEvent()
        } else if (this.form.receivingType == 1) {
          await this.$refs.editTable2.fullValidEvent()
        } else if (this.form.receivingType == 2) {
          await this.$refs.editTable3.fullValidEvent()
        }

我就嘗試先確定存在這個組件才調用這個方法，果然這樣可以

if (this.form.receivingType == 0) {
          this.$refs['editTable1'] && await this.$refs['editTable1'].fullValidEvent()
        } else if (this.form.receivingType == 1) {
          this.$refs['editTable2'] && await this.$refs['editTable2'].fullValidEvent()
        } else if (this.form.receivingType == 2) {
          this.$refs['editTable3'] && await this.$refs['editTable3'].fullValidEvent()
        }