分页列表数据不出来，初始化页面数据不出来的原因，Create中传一个参数1，解决bug的方法，学习敲代码的时候仔细与原项目比对，从上比到下

<template>
  <div id="app">
    <el-button type="primary" @click="dialogVisible = true">添加</el-button>
    <el-table :data="tableData">
      <el-table-column label="学号" prop="id"> </el-table-column>
      <el-table-column label="姓名" prop="name"> </el-table-column>
      <el-table-column label="生日" prop="birthday"> </el-table-column>
      <el-table-column label="学院" prop="college"> </el-table-column>
      <el-table-column label="专业" prop="major"> </el-table-column>
      <el-table-column align="right">
        <template v-slot="scope"
          ><el-button type="primary" @click="modify(scope.row)" plain style="width: 50px; font-size: 13px"
            >修改</el-button
          >
          <el-popconfirm
            confirmButtonText="好的"
            cancelButtonText="不用了"
            icon="el-icon-info"
            iconColor="red"
            @confirm="deleteStudent(scope.row.id)"
            title="这是一段内容确定删除吗？"
          >
            <template #reference>
              <el-button type="danger">删除</el-button>
            </template>
          </el-popconfirm>
        </template>
      </el-table-column>
    </el-table>
    <el-pagination
        background
        @current-change="handleCurrentChange"
        layout="prev,pager,next"
        :total="totalNum"
        @next-click="getList(pageNum+1)"
        @prev-click="getList(pageNum-1)"
        >
    </el-pagination>
    <el-dialog
      title="提示"
      v-model="dialogVisible"
      width="30%"
      :before-close="handleClose"
    >
      <el-form
        :model="ruleForm"
        status-icon
        ref="ruleForm"
        label-width="100px"
        class="demo-ruleForm"
      >
      <el-input type="text" v-model="ruleForm.id" v-show="false"></el-input>
        <el-form-item label="姓名">
          <el-input
            type="text"
            v-model="ruleForm.name"
          ></el-input>
        </el-form-item>
        <el-form-item label="生日">
          <el-input
            type="date"
            v-model="ruleForm.birthday"
          ></el-input>
        </el-form-item>
        <el-form-item label="学院">
          <el-input v-model.number="ruleForm.college"></el-input>
        </el-form-item>
        <el-form-item label="专业">
          <el-input v-model.number="ruleForm.major"></el-input>
        </el-form-item>
        <el-form-item>
          <el-button type="primary"
            >提交</el-button>
          <el-button @click="resetForm('ruleForm')">重置</el-button>
        </el-form-item>
      </el-form>
      <template #footer>
        <span class="dialog-footer">
          <el-button @click="dialogVisible = false">取 消</el-button>
          <el-button type="primary" @click="submitForm()" >
            确 定</el-button>
        </span>
      </template>
    </el-dialog>
  </div>
</template>
 
<script>
import axios from "axios";
// import axios from "axios";
export default {
  data() {
    return {
      tableData: [],
      search: "",
      url: "http://localhost:9090/crud",
      pageNum: 1,
      pageSize: 10,
      dialogVisible: false,
      ruleForm: {},
      totalNum: 0,
    };
  },
  methods: {
    handleCurrentChange(pageNum){
        this.getList(pageNum)
    },
    deleteStudent(id) {
      let that = this;
      axios
        .get(this.url + "/delete?id=" + id)
        .then(function (res) {
          if (res.data.success) {
            that.$message({
              type: "success",
              message: res.data.data,
            })
            that.getList(that.pageNum);
          } else {
            that.$message({
              type: "error",
              message: res.data.message,
            });
          }
        })
        .catch(function (res) {
          console.log(res);
          
        });
    },
    getList(pageNum) {
      let that = this;
      axios
        .post(this.url + "/list", {
          pageNum: pageNum,
          pageSize: this.pageSize,
        })
        .then(function (res) {
          console.log(res);
          that.tableData = res.data.data.records;
          that.totalNum = res.data.data.total
        })
        .catch(function (error) {
          alert("error!");
          console.log(error);
        });
    },
    modify(student){
        this.ruleForm = student
        this.dialogVisible = true
    }
    ,
    resetForm(){
        this.ruleForm = {}
    },
    submitForm(){
        console.log(this.ruleForm)
        let that = this
        if(!this.ruleForm.id){
        axios.post(this.url + "/add",this.ruleForm)
        .then(function (res) {
          console.log(res);
          if (res.data.success) {
            that.$message({
              type: "success",
              message: res.data.data,
            });
            that.getList(that.pageNum);
            // 跳转成功，弹框失效
            that.ruleForm = {}
            that.dialogVisible = false
          } else {
            that.$message({
              type: "error",
              message: res.data.message,
            });
          }
        })
        .catch(function (error) {
          alert("error!");
          console.log(error);
        });
        } else {
            axios.post(this.url+'/modify',this.ruleForm).then(function (res) {
                        console.log(res)
                        if(res.data.success){
                            that.$message({
                                type: 'success',
                                message: res.data.data
                            })
                            that.getList(1)
                            that.ruleForm = {}
                            that.dialogVisible = false
                        }else{
                            that.$message({
                                type: 'error',
                                message: res.data.message
                            })
                        }
                    }).catch(function (error) {
                        alert('error！')
                        console.log(error)
                    })
        }
    }
  },
  created() {
    this.getList(1);
  },
};
</script>
 
<style>
</style>