I am trying to create an excel file using Epplus package. I am doing this
static List<TestData> list = new List<TestData>
{
new TestData
{
Name = "Mohsin",
Number = 1
},
new TestData
{
Name = "Ali",
Number = 2
}
};
I am then calling this function
sheet.Cells["A1"].LoadFromCollection(list, true);
I saves the correct data to the file but missing headers and I want the members of my class to be the header here. Is there a way I can achieve it without hard coding? As I would be calling it from various different types of object types?
It's working for me like this:
sheet.Cells["A1"].LoadFromCollection(Collection: res, PrintHeaders: true);
also you may like this:
sheet.Cells["A1"].LoadFromCollection(list, true);
Probably you have some missing in your output file.
Related
Is there any 'easy' way to rename models in RavenDb when the database already has existing data? I have various models which were originally created in another language, and now I would like to rename them to English as the codebase is becoming quite unmaintainable. If I just rename them, then the data won't be loaded because the properties don't match anymore.
I would like the system to automatically do it on first load. Is there any best way how to approach this? My solution would be:
Check if a document exists to determine if the upgrade has been done or not
If upgrade has not been done, execute patch scripts to update fields
Update document to know that the upgrade has been done
I'd recommend you create new documents from the old documents.
This can be done pretty easily using patching via docStore.UpdateByIndex.
Suppose I had an old type name, Foo, and wanted to rename it to the new type name, Bar. And I wanted all the IDs to change from Foos/123 to Bars/123.
It would look something like this:
var patchScript = #"
// Copy all the properties from the old document
var newDoc = {};
for (var prop in this) {
if (prop !== '#metadata') {
newDoc[prop] = this[prop];
}
}
// Create the metadata.
var meta = {};
meta['Raven-Entity-Name'] = newCollection;
meta['Raven-Clr-Type'] = newType;
// Store the new document.
var newId = __document_id.replace(oldCollection, newCollection);
PutDocument(newId, newDoc, meta);
";
var oldCollection = "Foos";
var newCollection = "Bars";
var newType = "KarlCassar.Bar, KarlCassar"; // Where KarlCassar is your assembly name.
var query = new IndexQuery { Query = $"Tag:{oldCollection}" };
var options = new BulkOperationOptions { AllowStale = false };
var patch = new ScriptedPatchRequest
{
Script = patchScript,
Values = new Dictionary<string, object>
{
{ nameof(oldCollection), oldCollection },
{ nameof(newCollection), newCollection },
{ nameof(newType), newType }
}
};
var patchOperation = docStore.DatabaseCommands.UpdateByIndex("Raven/DocumentsByEntityName", query, patch, options);
patchOperation.WaitForCompletion();
Run that code once at startup, and then your app will be able to work with the new name entities. Your old entities are still around - those can be safely deleted via the Studio.
i have a database containing Song objects. The song class has > 30 properties.
My Music Tagging application is doing changes on a song on the file system.
It then does a lookup in the database using the filename.
Now i have a Song object, which i created in my Tagging application by reading the physical file and i have a Song object, which i have just retrieved from the database and which i want to update.
I thought i just could grab the ID from the database object, replace the database object with my local song object, set the saved id and store it.
But Raven claims that i am replacing the object with a different object.
Do i really need to copy every single property over, like this?
dbSong.Artist = songfromFilesystem.Artist;
dbSong.Album = songfromFileSystem.Album;
Or are there other possibilities.
thanks,
Helmut
Edit:
I was a bit too positive. The suggestion below works only in a test program.
When doing it in my original code i get following exception:
Attempted to associate a different object with id 'TrackDatas/3452'
This is produced by following code:
try
{
originalFileName = Util.EscapeDatabaseQuery(originalFileName);
// Lookup the track in the database
var dbTracks = _session.Advanced.DocumentQuery<TrackData, DefaultSearchIndex>().WhereEquals("Query", originalFileName).ToList();
if (dbTracks.Count > 0)
{
track.Id = dbTracks[0].Id;
_session.Store(track);
_session.SaveChanges();
}
}
catch (Exception ex)
{
log.Error("UpdateTrack: Error updating track in database {0}: {1}", ex.Message, ex.InnerException);
}
I am first looking up a song in the database and get a TrackData object in dbTracks.
The track object is also of type TrackData and i just put the ID from the object just retrieved and try to store it, which gives the above error.
I would think that the above message tells me that the objects are of different types, which they aren't.
The same error happens, if i use AutoMapper.
any idea?
You can do what you're trying: replace an existing object using just the ID. If it's not working, you might be doing something else wrong. (In which case, please show us your code.)
When it comes to updating existing objects in Raven, there are a few options:
Option 1: Just save the object using the same ID as an existing object:
var song = ... // load it from the file system or whatever
song.Id = "Songs/5"; // Set it to an existing song ID
DbSession.Store(song); // Overwrites the existing song
Option 2: Manually update the properties of the existing object.
var song = ...;
var existingSong = DbSession.Load<Song>("Songs/5");
existingSong.Artist = song.Artist;
existingSong.Album = song.Album;
Option 3: Dynamically update the existing object:
var song = ...;
var existingSong = DbSession.Load<Song>("Songs/5");
existingSong.CopyFrom(song);
Where you've got some code like this:
// Inside Song.cs
public virtual void CopyFrom(Song other)
{
var props = typeof(Song)
.GetProperties(System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance)
.Where(p => p.CanWrite);
foreach (var prop in props)
{
var source = prop.GetValue(other);
prop.SetValue(this, source);
}
}
If you find yourself having to do this often, use a library like AutoMapper.
Automapper can automatically copy one object to another with a single line of code.
Now that you've posted some code, I see 2 things:
First, is there a reason you're using the Advanced.DocumentQuery syntax?
// This is advanced query syntax. Is there a reason you're using it?
var dbTracks = _session.Advanced.DocumentQuery<TrackData, DefaultSearchIndex>().WhereEquals("Query", originalFileName).ToList();
Here's how I'd write your code using standard LINQ syntax:
var escapedFileName = Util.EscapeDatabaseQuery(originalFileName);
// Find the ID of the existing track in the database.
var existingTrackId = _session.Query<TrackData, DefaultSearchIndex>()
.Where(t => t.Query == escapedFileName)
.Select(t => t.Id);
if (existingTrackId != null)
{
track.Id = existingTrackId;
_session.Store(track);
_session.SaveChanges();
}
Finally, #2: what is track? Was it loaded via session.Load or session.Query? If so, that's not going to work, and it's causing your problem. If track is loaded from the database, you'll need to create a new object and save that:
var escapedFileName = Util.EscapeDatabaseQuery(originalFileName);
// Find the ID of the existing track in the database.
var existingTrackId = _session.Query<TrackData, DefaultSearchIndex>()
.Where(t => t.Query == escapedFileName)
.Select(t => t.Id);
if (existingTrackId != null)
{
var newTrack = new Track(...);
newTrack.Id = existingTrackId;
_session.Store(newTrack);
_session.SaveChanges();
}
This means you already have a different object in the session with the same id. The fix for me was to use a new session.
I am using Google diff-match-patch JAVA plugin to create patch between two JSON strings and storing the patch to database.
diff_match_patch dmp = new diff_match_patch();
LinkedList<Patch> diffs = dmp.patch_make(latestString, originalString);
String patch = dmp.patch_toText(diffs); // Store patch to DB
Now is there any way to use this patch to re-create the originalString by passing the latestString?
I google about this and found this very old comment # Google diff-match-patch Wiki saying,
Unpatching can be done by just looping through the diff, swapping
DIFF_INSERT with DIFF_DELETE, then applying the patch.
But i did not find any useful code that demonstrates this. How could i achieve this with my existing code ? Any pointers or code reference would be appreciated.
Edit:
The problem i am facing is, in the front-end i am showing a revisions module that shows all the transactions of a particular fragment (take for example an employee details), like which user has updated what details etc. Now i am recreating the fragment JSON by reverse applying each patch to get the current transaction data and show it as a table (using http://marianoguerra.github.io/json.human.js/). But some JSON data are not valid JSON and I am getting JSON.parse error.
I was looking to do something similar (in C#) and what is working for me with a relatively simple object is the patch_apply method. This use case seems somewhat missing from the documentation, so I'm answering here. Code is C# but the API is cross language:
static void Main(string[] args)
{
var dmp = new diff_match_patch();
string v1 = "My Json Object;
string v2 = "My Mutated Json Object"
var v2ToV1Patch = dmp.patch_make(v2, v1);
var v2ToV1PatchText = dmp.patch_toText(v2ToV1Patch); // Persist text to db
string v3 = "Latest version of JSON object;
var v3ToV2Patch = dmp.patch_make(v3, v2);
var v3ToV2PatchTxt = dmp.patch_toText(v3ToV2Patch); // Persist text to db
// Time to re-hydrate the objects
var altV3ToV2Patch = dmp.patch_fromText(v3ToV2PatchTxt);
var altV2 = dmp.patch_apply(altV3ToV2Patch, v3)[0].ToString(); // .get(0) in Java I think
var altV2ToV1Patch = dmp.patch_fromText(v2ToV1PatchText);
var altV1 = dmp.patch_apply(altV2ToV1Patch, altV2)[0].ToString();
}
I am attempting to retrofit this as an audit log, where previously the entire JSON object was saved. As the audited objects have become more complex the storage requirements have increased dramatically. I haven't yet applied this to the complex large objects, but it is possible to check if the patch was successful by checking the second object in the array returned by the patch_apply method. This is an array of boolean values, all of which should be true if the patch worked correctly. You could write some code to check this, which would help check if the object can be successfully re-hydrated from the JSON rather than just getting a parsing error. My prototype C# method looks like this:
private static bool ValidatePatch(object[] patchResult, out string patchedString)
{
patchedString = patchResult[0] as string;
var successArray = patchResult[1] as bool[];
foreach (var b in successArray)
{
if (!b)
return false;
}
return true;
}
There's a variable persistence concept I have integrated multiple times:
// Standard initialiation
boolean save = true;
Map<String, Object> dataHolder;
// variables to persist
int number = 10;
String text = "I'm saved";
// Use the variables in various ways in the project
void useVariables() { ... number ... text ...}
// Function to save the variables into a datastructure and for example write them to a file
public Map<String, Object> getVariables()
{
Map<String, Object> data = new LinkedHashMap<String, Object>();
persist(data);
return(data);
}
// Function to load the variables from the datastructure
public void setVariables(Map<String, Object> data)
{
persist(data);
}
void persist(Map<String, Object> data)
{
// If the given datastructure is empty, it means data should be saved
save = (data.isEmpty());
dataHolder = data;
number = handleVariable("theNumber", number);
text = handleVariable("theText", text);
...
}
private Object handleVariable(String name, Object value)
{
// If currently saving
if(save)
dataHolder.put(name, value); // Just add to the datastructure
else // If currently writing
return(dataHolder.get(name)); // Read and return from the datastruct
return(value); // Return the given variable (no change)
}
The main benefit of this principle is that you only have a single script where you have to mention new variables you add during the development and it's one simple line per variable.
Of course you can move the handleVariable() function to a different class which also contains the "save" and "dataHolder" variables so they wont be in the main application.
Additionally you could pass meta-information, etc. for each variable required for persisting the datastructure to a file or similar by saving a custom class which contains this information plus the variable instead of the object itself.
Performance could be improved by keeping track of the order (in another datastructure when first time running through the persist() function) and using a "dataHolder" based on an array instead of a search-based map (-> use an index instead of a name-string).
However, for the first time, I have to document this and so I wondered whether this function-reuse principle has a name.
Does someone recognize this idea?
Thank you very much!
I'm using PetaPoco T4 Template (http://www.hanselman.com/blog/T4TextTemplateTransformationToolkitCodeGenerationBestKeptVisualStudioSecret.aspx), It always converting table names, for example it converts a table named "Media" to "Medium". Have you any idea how can I make it to stop doing that?
Thanks
In your .Database.tt file you can tweak the class names to your liking for each table:
tables["Media"].ClassName = "Media";
I don't know of a way to turn this off everywhere. I believe it is a remnant from the SubSonic inflector. In the SchemaReader classes you will see a call like this:
tbl.ClassName=Inflector.MakeSingular(tbl.CleanName);
You could try changing that to
tbl.ClassName=tbl.CleanName;
To prevent that, I put always this piece of code in the Database.tt file:
// Read schema
var tables = LoadTables();
foreach(Table t in tables)
{
if(!t.Name.ToLower().StartsWith("tablePrefix_"))
{
// Filter tables by prefix
t.Ignore = true;
}
else
{
// This do the trick discussed here
t.ClassName = t.CleanName;
}
}