如何使用C＃从UWP中的SQLite数据库检索字节数组

Question

I've searched for too long but couldn't find any answer.

I'm working on a UWP app which stores BitmapImage data (converted to byte array) into a blob field in an SQLite3 database. However, I can't find a way to retrieve the data once it's saved in the database.

All the solutions I've seen use the GetBytes method from Microsoft.Data.SQLite.SQLiteDataReader but Microsoft's documentation indicates method is "not supported". https://docs.microsoft.com/en-us/dotnet/api/microsoft.data.sqlite.sqlitedatareader.getbytes?view=msdata-sqlite-1.1.0

Can anyone please show some sample code how to retrieve the blob from the SQLite 3 database and convert it to a BitmapImage for display?

Thanks in advance for your help.

Answer 1

That is a really minimal version of the work required but that gives you the step that will store picture data as btye[] 's also that will retrieve the data as a byte array.

I won't go into full depth of the entity framework because that isn't a part of the question, I believe this link does a good job. Microsoft Documentation .

Disclaimer I have never used the entity framework with UWP, as well I have never used a SQL Lite database, there may be things with the amount of data and all the available types that can be stored in the database.

As for the converting byte[] to BitMap in UWP, look here .

public class ProfilePictures
{
    public int ProfilePicturePK {get;set;}
    public byte[] PictureData {get;set;}
}

... all the other entity setup, see link for entity setup

public byte[] GetPictureData(int id)
{
    return GetPictureDataAsync(id).Wait();
}

//If you want to make things a little more UI and thread friendly
public async Task<byte[]> GetPictureDataAsync(int id)
{
     await Task.Factory.StartNew(()=>{
        using(var db = Context)
        {
            return (from pictures in db.ProfilePictures where pictures.ProfilePicturePK == id select pictures).SingleOrDefault();
        }
     });
}