C#•4mo ago

How to connect my c# backend with the frontend?

Hello, I created a ASP NET Core Web Api project with the command dotnet new webapi -minimal. In my program.cs I am fetching some data from a public server and displaying it in plaintext for now when I run it and open localhost. So it works perfectly but since I am a beginner I have two questions. 1. Is my code and approach fine the way I did it? Is there anything what I can improve? 2. How can I connect this with a React frontend to display the some values from the fetch? I know how to work with react but I am missing the link how to connect each other? I uploaded the code on github here: https://github.com/BearCooder/ASP.NET-Core Basically the code is only in program.cs I appreciate any help!

13 Replies

Keswiik•4mo ago

manually adding a react app to an existing asp.net project can be a bit of a hassle, if you have VS or Rider there should be templates for ASP projects that include react It would probably be easier for you to create a new project (that supports react already) and then copy your existing code over

BearCooder•4mo ago

Ah I did not know this. I use VSCode. I was looking for a best practice how to work with c# and react but at the end I was not sure whats the right approach to be honest

Keswiik•4mo ago

I would personally recommend using a proper IDE instead of VSCode for working with c# but there are probably ways to create templated projects from the CLI

Pobiega•4mo ago

There are, it's a template of its own However you don't need to use that template. It's very common to simply run your react app on its own Set up a dev proxy to redirect your api traffic, and thats all you need

BearCooder•4mo ago

So you mean something like adding a proxy in my package json where my react app e.g. "proxy": "http://localhost:5000"? And using the port where my ASP NET Core app is running.

Pobiega•4mo ago

Yeah, something like that We use vite at work and have that setup It works great

BearCooder•4mo ago

Ok that sounds good I also use Vite with React. And then I should be able to display certain data with axios?

Pobiega•4mo ago

well, axios lets you make requests to the backend, yes then you do react stuff with that data to show it 🙂

Angius•4mo ago

Or you can ditch Axios and just use fetch() ¯\_(ツ)_/¯

BearCooder•4mo ago

Yes true. I just have a problem to make a successfull request to my ASP NET Core app to see the data on the frontend. And I was trying either with axios or fetch. This is what I try in React. The backend code is in my program.cs in the github link. No matter what I try I get TypeErrors in browser console. And now its patient.name.given is undefined.

import React, { useEffect, useState } from 'react';

interface Patient {
  id: string;
  name: { family: string; given: string[] };
  birthDate: string;
  identifier: { value: string }[];
}

const DataList: React.FC = () => {
  const [patients, setPatients] = useState<Patient[]>([]);

  useEffect(() => {
    const fetchData = async () => {
      const response = await fetch('http://localhost:4000/patient');
      const data: { entry: { resource: Patient }[] } = await response.json();
      setPatients(data.entry.map((entry) => entry.resource));
    };

    fetchData();
  }, []);

  return (
    <div>
      <h2>Patient List</h2>
      <table>
        <thead>
          <tr>
            <th>Id</th>
            <th>Given Name</th>
            <th>Family Name</th>
            <th>Birth Date</th>
            <th>Identifier</th>
          </tr>
        </thead>
        <tbody>
          {patients.map((patient) => (
            <tr key={patient.id}>
              <td>{patient.id}</td>
              <td>{patient.name.given.join(' ')}</td>
              <td>{patient.name.family}</td>
              <td>{patient.birthDate}</td>
            </tr>
          ))}
        </tbody>
      </table>
    </div>
  );
};

export default DataList;

import React, { useEffect, useState } from 'react';

interface Patient {
  id: string;
  name: { family: string; given: string[] };
  birthDate: string;
  identifier: { value: string }[];
}

const DataList: React.FC = () => {
  const [patients, setPatients] = useState<Patient[]>([]);

  useEffect(() => {
    const fetchData = async () => {
      const response = await fetch('http://localhost:4000/patient');
      const data: { entry: { resource: Patient }[] } = await response.json();
      setPatients(data.entry.map((entry) => entry.resource));
    };

    fetchData();
  }, []);

  return (
    <div>
      <h2>Patient List</h2>
      <table>
        <thead>
          <tr>
            <th>Id</th>
            <th>Given Name</th>
            <th>Family Name</th>
            <th>Birth Date</th>
            <th>Identifier</th>
          </tr>
        </thead>
        <tbody>
          {patients.map((patient) => (
            <tr key={patient.id}>
              <td>{patient.id}</td>
              <td>{patient.name.given.join(' ')}</td>
              <td>{patient.name.family}</td>
              <td>{patient.birthDate}</td>
            </tr>
          ))}
        </tbody>
      </table>
    </div>
  );
};

export default DataList;

Keswiik•4mo ago

so log the result you're getting from the fhir api and make sure it contains what you're expecting?

Keswiik•4mo ago

https://github.com/BearCooder/ASP.NET-Core/blob/cacc0433de246c61d75df2d0ca7790aaa007459a/Program.cs#L27 if this is still how you have it written, I would expect things to fail

GitHub

ASP.NET-Core/Program.cs at cacc0433de246c61d75df2d0ca7790aaa007459a...

Contribute to BearCooder/ASP.NET-Core development by creating an account on GitHub.

Keswiik•4mo ago

you aren't returning a valid json object here

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How to connect my c# backend with the frontend?