How to implement an upload form in .Net Core API?

Question

I create a .Net Core API ( I use swagger with it).

I create a controller in order to upload a picture to link it to an item.

.cs :

[HttpPut("[Action]/{id}")]
public async Task<ActionResult> Link(int id, IFormFile file)
{
    var item = await _context.Item.FirstOrDefaultAsync(t => t.Id == id);
    if (item == null)
    {
        return BadRequest("item null");
    }

    using (var memoryStream = new MemoryStream())
    {
        await file.CopyToAsync(memoryStream);
        // code to link
        return Ok(file);
    }
}

My issue is if I want to test to know if it works, I have to use postman but I want to test it in my api.

A solution exist for my issue ? For the moment it look like that :

What is your .net core version and swagger version?

Edward
– Edward

2019-07-23 05:09:12 +00:00
Commented Jul 23, 2019 at 5:09 — Edward
– Edward, Commented Jul 23, 2019 at 5:09

Edward · Accepted Answer · 2019-07-23 05:12:39Z

For Swashbuckle.AspNetCore with 4.0.1 and Swashbuckle.AspNetCore.Swagger with 4.0.1, it supports IFormFile with swagger/index.html.

Detail steps:

Install package Swashbuckle.AspNetCore with 4.0.1 and Swashbuckle.AspNetCore.Swagger with 4.0.1

Startup.cs

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
        services.AddSwaggerGen(c =>
        {
            c.SwaggerDoc("v1", new Info { Title = "My API", Version = "v1" });
        });

    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        else
        {
            // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
            app.UseHsts();
        }

        app.UseHttpsRedirection();
        // Enable middleware to serve generated Swagger as a JSON endpoint.
        app.UseSwagger();
        // Enable middleware to serve swagger-ui (HTML, JS, CSS, etc.),
        // specifying the Swagger JSON endpoint.
        app.UseSwaggerUI(c =>
        {
            c.SwaggerEndpoint("/swagger/v1/swagger.json", "My API V1");
        });

        app.UseMvc();
    }
}

ApiController

[Route("api/[controller]")]
[ApiController]
public class ValuesController : ControllerBase
{
    [HttpPut("[Action]/{id}")]
    public async Task<ActionResult> Link(int id, IFormFile file)
    {
        return Ok(id);
    }
}

Chris Pratt · Accepted Answer · 2019-07-22 15:07:55Z

2

IFormFile only works for multipart/form-data encoded requests. To send via JSON, you need to bind to byte[], and then send the file data as either a Base64-encoded string or a uint array (i.e. the JSON equivalent of a byte[].

Also, JSON is an object notation format, so you must bind to an object. For example:

public class MyFileUploadModel
{
    public byte[] File { get; set; }
}

Then:

public async Task<IActionResult> Link(int id, MyFileUploadModel model)

Finally, you'd send a JSON object like:

{
    "file": "[base64 encoded string here]"
}

OR

{
    "file": [1, 2, 3]
}

Where [1, 2, 3] would actually be an array of the bytes in the file (i.e. numbers 0-255).

answered Jul 22, 2019 at 15:07

Chris Pratt

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