Xamarin form - how to upload and retrieve image using sql server web api

As a best practice, you should not save the image directly into SQL server unless it is really necessary. Read more in this link.

To answer your question, follow the below steps.

1. Convert the image into Base64.

   public static async Task<string> Convertbase64Async (Stream stream)
   {
       var bytes = new byte[stream.Length];
       await stream.ReadAsync(bytes, 0, (int)stream.Length);
       string base64 = Convert.ToBase64String(bytes);
       return base64;
   }
   

2. Now the image will be in a string format. Do the inserting.

   INSERT INTO table_name (column1, column2, column3, ...) VALUES (value1, value2, value3, ...);

3. When you want to display back the image, retrieve the image from SQL using SELECT query.

4. Convert the Base64 back into Image format.

   public Image LoadImage(String base_64)
   {
       byte[] bytes = Convert.FromBase64String(base_64);
   
       Image image;
       using (MemoryStream ms = new MemoryStream(bytes))
       {
           image = Image.FromStream(ms);
       }
   
       return image;
   }
   

For references: Bas64 to image, Best practices