记一次element ui 表单for循环校验

                                      <el-form-item class="img-item-wrapper" v-for="(item, idx) in form.nativeExtInfo.mainImages" :key="idx">
                                            <div class="img-size-wrapper">
                                                <el-form-item
                                                    label="宽："
                                                    :prop="'nativeExtInfo.mainImages.' + idx + '.width'"
                                                    :rules="rules.img">
                                                    <el-input class="input-size" type="number" v-model="item.width" size="small"></el-input>
                                                </el-form-item>
                                                <el-form-item
                                                    label="高："
                                                    :prop="'nativeExtInfo.mainImages.' + idx + '.high'"
                                                    :rules="rules.img">
                                                    <el-input class="input-size" type="number" v-model="item.high" size="small"></el-input>
                                                </el-form-item>
                                                <!-- <div>宽:<el-input class="input-size" type="number" v-model="item.width" size="small"></el-input></div>
                                                <div>高:<el-input class="input-size" type="number" v-model="item.high" size="small"></el-input></div> -->
                                            </div>
                                            <el-form-item                                         
                                                v-for="(img, i) in item.imageInfo" 
                                                :key="i"
                                                :prop="'nativeExtInfo.mainImages.' + idx + '.imageInfo.'+i+'.url'"
                                                :rules="rules.imgUrl">
                                                <div class="img-list-wrapper add-value-wrapper" >
                                                    <el-input placeholder="url" v-model.trim="img.url" clearable size="small"></el-input>
                                                    <i class="el-icon-plus add" @click="addUrl(idx, i , 'mainImages')"></i>
                                                    <i class="el-icon-close del" v-show="i > 0" @click="delUrl(idx, i , 'mainImages')"></i>
                                                </div>
                                            </el-form-item>
                                            <div class="del-img-wrapper" v-if="idx > 0" @click="delImages(idx , 'mainImages')">
                                                <i class="el-icon-circle-close"></i>
                                            </div>
                                        </el-form-item>