问React /Typescript："TypeError: blogs.map不是一个函数“(我已经将博客输入为一个‘数组’)

EN

import * as React from "react";
import { useState, useEffect } from "react";
import { IBlog } from "../utils/interfaces";
import BlogPreview from "../components/BlogPreview";
import { json } from "../utils/api";

export interface HomeProps {}

const Home: React.SFC<HomeProps> = () => {
  const [blogs, setBlogs] = useState<IBlog[]>([]);

  useEffect(() => {
    (async () => {
      try {
        let blogs = await json("/api/blogs");
        setBlogs(blogs);
      } catch (error) {
        console.log(error);
      }
    })();
  }, []); 

  return (
    <>
      <div>
        <h2 className="row m-4 justify-content-center text-secondary">
          Blog Feed
        </h2>
      </div>
      <main className="col">
        <section className="row my-5 justify-content-center">
          {blogs.map(blog => {
            return <BlogPreview key={`blog-${blog.id}`} blog={blog} />;
          })}
        </section>
      </main>
    </>
  );
};

export default Home;

export interface IBlog {
    id: number,
    title: string,
    content: string,
    _created: Date,
    name: string
}

import { Router, Request } from "express";
import db from "../../db";

router.get("/", async (req, res, next) => {
  try {
    let blogs = await db.Blogs.getAll();
    res.json(blogs);
  } catch (error) {
    console.log(error);
    res.sendStatus(500);
  }
});

export default router;

import fetch from 'isomorphic-fetch';

export let AccessToken: string = localStorage.getItem('token') || null;
export let User: any = {
    userid: localStorage.getItem('userid') || null,
    role: localStorage.getItem('role') || null
}

export const json = async <T = any>(uri: string, method: string = 'GET', body?: {}) => {
    let headers: any = {
        'Content-type': 'application/json'
    };

    if (AccessToken) {
        headers['Authorization'] = `Bearer ${AccessToken}`;
    }
    try {
        let result = await fetch(uri, {
            method,
            headers,
            body: JSON.stringify(body)
        });
        if (result.ok) {
            return <T>(await result.json());
        } else {
            return false;
        }
        
    } catch (error) {
        console.log(error);
        throw error;
    }
};

export const SetAccessToken = (token: string, user: {} = { userid: undefined, role: 'guest'}) => {
    AccessToken = token;
    User = user;
    localStorage.setItem('token', token);
    localStorage.setItem('userid', User.userid);
    localStorage.setItem('role', User.role);
}