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Frequent Visitor

Retrieving Data URI from an image added via the "Add picture" control

I am trying to submit a photo taken from a PowerApps app to a custom API. There are a number of tutorials written for it, but they all use the built-in camera control, which is very limiting as far as photo-taking goes. It seems that the recent addition of native camera functionality (https://powerapps.microsoft.com/en-us/blog/powerapps-v610/) should work much better, however I am struggling with obtaining the image data from the "Add picture" control.

 

The problem narrows down to the following: when you obtain image data from the Camera control (using the Camera1.Photo property) you get a long Data URI string containing the actual image, it like this:

 

data&colon;image/jpeg;base64<long base64 string follows>

 

When I obtain the image from the "Add picture" control (using AddMediaButton1.Media property) I get a string that looks like this:

 

blob:https://us.create.powerapps.com/dd6409a9-1b09-4ef5-a64b-21c84b16bb54 (if using the web player)
blob:http://127.0.0.1:49428/b7371d5a-bec9-45da-acb4-e2c6a1fefff6 (if using the Android player)

 

So it seems that instead of the actual image content I am getting some kind of a reference to a local blob storage, which is of no use for the purposes of passing it to the API that is expecting the actual image.

 

QUESTION: how can I obtain a proper Data URI string containing the actual image from the "Add picture" control?

27 REPLIES 27
Highlighted

Thanks Claudio for your solution however would it be possible to create a similar example running WebAPI? Also could you provide the full code? 

 

Another question. Where is 

IFormFile coming from?

 

Thirdly, Do you have an ETA when Add Photos functionality similar to the Camera control will be released for GA in PowerApps ?

 

I desperately need it.

 

Thanks

Highlighted
Frequent Visitor

Here are my "using" statements:

 

using System;
using System.IO;
using System.Net;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using System.Web.Http;

Here are my nuget packages:

 

  <package id="Microsoft.AspNet.WebApi" version="5.2.3" targetFramework="net452" />
  <package id="Microsoft.AspNet.WebApi.Client" version="5.2.3" targetFramework="net452" />
  <package id="Microsoft.AspNet.WebApi.Core" version="5.2.3" targetFramework="net452" />
  <package id="Microsoft.AspNet.WebApi.WebHost" version="5.2.3" targetFramework="net452" />
  <package id="Microsoft.Net.Compilers" version="1.3.2" targetFramework="net452" developmentDependency="true" />
  <package id="Microsoft.Web.Infrastructure" version="1.0.0.0" targetFramework="net452" />
  <package id="Newtonsoft.Json" version="9.0.1" targetFramework="net452" />
  <package id="WebActivatorEx" version="2.2.0" targetFramework="net452" />

Don't worry about the DataAccess class that you highlighted in blue -- that's some internal code specific to my app.

 

 

And to answer your question about IFormFile, I think it's a .Net Core class, I ended up not using it.

Highlighted
Frequent Visitor

Thanks a lot for your quick response. I will try it out and revert back hopefully with good news. 🙂

 

One final question what is this function returning? 

 result = DataAccess.Sharepoint.UploadFile(entityId, saveToPath);

 

Is it a bool field? true or false? 

Highlighted
Frequent Visitor

Yes, bool.

Highlighted
Frequent Visitor

Hi, sorry to bother you but im getting this error when i compile in Azure functions....

 

 

 
2017-07-13T21:14:50.336 Script for function 'HttpTriggerCSharp1' changed. Reloading.
2017-07-13T21:14:50.431 (20,22): error CS0103: The name 'Request' does not exist in the current context
2017-07-13T21:14:50.431 (26,23): error CS0103: The name 'Request' does not exist in the current context
2017-07-13T21:14:50.431 (46,24): error CS0103: The name 'InternalServerError' does not exist in the current context
2017-07-13T21:14:50.431 (49,20): error CS0103: The name 'Ok' does not exist in the current context
2017-07-13T21:14:50.446 error AF001: Your function must contain a single public method, a public method named 'Run', or a public method matching the name specified in the 'entryPoint' metadata property.
2017-07-13T21:14:50.446 Compilation failed.

 

 

 

 

Below is my Azure Function -- HTTP Trigger WebAPI

 

 

using System;
using System.IO;
using System.Net;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using System.Web.Http;

 

public async Task<IHttpActionResult> UploadImage(int entityId)
{
const string storagePath = @"C:\temp";
var result = false;

try
{
// Check if the request contains multipart/form-data.
if (!Request.Content.IsMimeMultipartContent())
throw new HttpResponseException(HttpStatusCode.UnsupportedMediaType);

var provider = new MultipartFormDataStreamProvider(storagePath);

// Read the form data.
await Request.Content.ReadAsMultipartAsync(provider);

// This illustrates how to get the file names.
var fileData = provider.FileData[0];
if (string.IsNullOrEmpty(fileData.Headers.ContentDisposition.FileName))
throw new HttpResponseException(HttpStatusCode.InternalServerError);

var fileName = fileData.Headers.ContentDisposition.FileName;
fileName = fileName.Trim('"');

var saveToPath = Path.Combine(storagePath, fileName);

//temporarily save the file locally to be later uploaded to Sharepoint
File.Move(fileData.LocalFileName, saveToPath);

result = false; //DataAccess.Sharepoint.UploadFile(entityId, saveToPath);

}
catch (Exception e)
{
return InternalServerError(e);
}

return Ok(result);

}

 

Highlighted
Frequent Visitor

My code runs as a ASP.Net 4.5 Web API method on IIS, which is a different context than Azure functions. Your error seems specific to the latter, so maybe someone with knowledge of Azure Functions can help out.

Highlighted
Helper II
Helper II

Hi,

 

Has anyone managed to get this working using an Azure Function / Azure API?

 

I've been scouring the internet attempting to find ways to convert the BLOB format to Data URI / An image byt been very unsuccessful.

 

Any help would be very much appreciated.

 

Thanks again,

Kind regards,

J

Highlighted

I currently use a Flow to upload my image, i perform an action on the byte stream in Azure functions, then pass it to an Azure blob connector to save it in Azure Blob Storage.  I am trying something similiar now with the AddMedia control, but am still just getting the blob address being passed and not the blob itself.

 

Has there been any further developments on this to have it act just like the image control and pass the base64 encoded string for us to work with as that works great?

 

The image control, the pen control, the camera control and the add media should all handle "images" the same way.

Highlighted

More info...

 

I call my Flow with this code from in PowerApps to succesfully upload an image to Azure blob storage: 

UploadDeviceImage.Run(UploadedImage1.Image, "/inventorypictures/TestFolder/", "DeviceImage.jpg")

 

Here is my working Azure function that the flow calls:

using System.Net;
using System.Net.Http;
using System.Net.Http.Headers;

public static async Task<HttpResponseMessage> Run(HttpRequestMessage req, TraceWriter log)
{

    string body = await req.Content.ReadAsStringAsync();  // read image/jpeg;base64
    body = body.Replace("data&colon;image/jpeg;base64,", "");   // remove the header
    var bytes = Convert.FromBase64String(body);           // convert data to bytes
    
    var response = new HttpResponseMessage()
    {
        Content = new ByteArrayContent(bytes),            // write binary out to pass to create blob
        StatusCode = HttpStatusCode.OK,
    };
    response.Content.Headers.ContentType = new MediaTypeHeaderValue("image/jpeg");
    return response;
}

And here is my Flow, which calls the function above and the blob connector:

MicrosoftFlowPic.PNG

 

Pretty simple.  How do i replicate this with the AddMedia control?

 

Based code mentioned in this thread, i created a new Azure function to look like this, but i just get the blog address still:

#r "System.Web"
using System.Web; 
using System.Net;
using System.Net.Http;
using System.Net.Http.Headers;

public static async Task<HttpResponseMessage> Run(HttpRequestMessage req, TraceWriter log)
{
    byte[] bytes = null;

    if (!req.Content.IsMimeMultipartContent())
    {
        return new HttpResponseMessage()
        {
            StatusCode = HttpStatusCode.UnsupportedMediaType
        };
    }        

    var filesReadToProvider = await req.Content.ReadAsMultipartAsync();

    foreach (var stream in filesReadToProvider.Contents)
    {
        bytes = await stream.ReadAsByteArrayAsync();
    }

    var response = new HttpResponseMessage()
    {
        Content = new ByteArrayContent(bytes),            // write binary out
        StatusCode = HttpStatusCode.OK,
    };
    response.Content.Headers.ContentType = new MediaTypeHeaderValue("image/jpeg");
    return response;
}

Any ideas?

 

 

Highlighted
Advocate I
Advocate I

As low code platforms goes, this is a complete fail. If you have to do this much trouble to get the image bits.... as some people say here, the "add picture" control is completely useless this way.

 

 

I have tried a lot of things specified here, but if you have to roll your own api... that's just wrong, that's not low code anymore.

 

Either allow the camera to take high resolution image or make "add picture" easier to use. But this problem is far from solved in my book!

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