Monday, May 4, 2020

C# MongoDB Data Access Layer Explained

In our previous post, we discussed about writing a data access layer for mongodb. So, let's discuss a bit about each method.

     public bool Insert<T>(T RecordToInsert)  
     {  
       return Insert<T>(typeof(T).Name, RecordToInsert);  
     }  
     public bool Insert<T>(string TableName, T RecordToInsert)  
     {  
       Connect();  
       var collection = mongoDatabase.GetCollection<T>(TableName);  
       collection.InsertOne(RecordToInsert);  
       return true;  
     } 

This methods are used to insert records to a specific collection. The T is a generic type which you can pass any entity. For example, lets say you have a Person class. and you are going to add a new person. So what you need is to pass the Person object  to this method. Normally collections are named as the class name so that it's not going to be clear.

 public bool Insert(Person p)  
     {  
       return dal.Insert(p);         
     }  

The sample Person class will looks like below. You must have the
[BsonId]      
     public ObjectId _id { get; set; } 

so that the MongoDB can keep the unique code generated upon saving a new person.

   public class Person  
   {  
     private int _idPerson;  
     private string _mobileNumber;  
     private string _lastName;  
     private string _firstName;  
     private string _username;  
     private string _password;  
     private DateTime _lastModified;  
     [BsonId]      
     public ObjectId _id { get; set; }  
     public int IdPerson  
     {  
       get { return _idPerson; }  
       set { _idPerson = value; }  
     }  
     public string FirstName  
     {  
       get { return _firstName; }  
       set { _firstName = value; }  
     }      
     public string LastName  
     {  
       get { return _lastName; }  
       set { _lastName = value; }  
     }  
     public string MobileNumber  
     {  
       get { return _mobileNumber; }  
       set { _mobileNumber = value; }  
     }  
     public string Username  
     {  
       get { return _username; }  
       set { _username = value; }  
     }  
     public string Password  
     {  
       get { return _password; }  
       set { _password = value; }  
     }      
     public DateTime LastModified  
     {  
       get { return _lastModified; }  
       set { _lastModified = value; }  
     }      
   }  

Lets see how we can use replace function to update/replace a specific record.

     public bool Replace<T>(T RecordToUpsert, string UpdateColumnName, BsonValue WhereValue)  
     {  
       return Replace<T>(typeof(T).Name, RecordToUpsert, UpdateColumnName, WhereValue);  
     }  
     public bool Replace<T>(string TableName, T RecordToUpsert, string UpdateColumnName, BsonValue WhereValue)  
     {  
       Connect();  
       var filter = Builders<T>.Filter.Eq(UpdateColumnName, WhereValue);        
       var collection = mongoDatabase.GetCollection<T>(TableName);        
       var result = collection.ReplaceOne(filter, RecordToUpsert);  
       return result.IsAcknowledged;  
     }  

This 2 methods will help with our update / replace of persons as below.

     public bool Replace(Person p)  
     {  
       return dal.Replace(p, "IdPerson", p.IdPerson);  
     }  

Here we have the p as Person object that has all the existing and modified data. Also we use IdPerson as the key to update the person.

So, the deletion is done as below.
     public void Delete<T>(BsonValue WhereValue)  
     {  
       Delete<T>(typeof(T).Name, "_id", WhereValue);  
     }  
     public void Delete<T>(string DeleteColumnName, BsonValue WhereValue)  
     {  
       Delete<T>(typeof(T).Name, DeleteColumnName, WhereValue);  
     }      
     public void Delete<T>(string TableName, string DeleteColumnName, BsonValue WhereValue)  
     {  
       Connect();  
       var collection = mongoDatabase.GetCollection<T>(TableName);  
       var filter = Builders<T>.Filter.Eq(DeleteColumnName, WhereValue);  
       collection.DeleteOne(filter);  
     }

So, you can either use _id which is MongoDB ID value of  the record to delete or you can pass a matching attribute with it's value to delete.

Finally, the selection can be done like this;

     public List<T> Select<T>()  
     {  
       return Select<T>(typeof(T).Name);  
     }  
     public List<T> Select<T>(string TableName)  
     {  
       Connect();  
       var collection = mongoDatabase.GetCollection<T>(TableName);  
       return collection.Find(new BsonDocument()).ToList();  
     }  
     public List<T> Select<T>(BsonValue WhereValue, string SelectColumnName = null)  
     {  
       Connect();  
       if (string.IsNullOrEmpty(SelectColumnName))  
         SelectColumnName = "_id";  
       return Select<T>(typeof(T).Name, SelectColumnName, WhereValue);  
     }  
     public List<T> Select<T>(string TableName, string SelectColumnName, BsonValue WhereValue)  
     {  
       Connect();  
       var collection = mongoDatabase.GetCollection<T>(TableName);  
       var filter = Builders<T>.Filter.Eq(SelectColumnName, WhereValue);  
       return collection.Find(filter).ToList();  
     }

Methods can  be used as ;

     public List<Person> Select()  
     {  
       return dal.Select<Person>();  
     }  

The matching type Person will return a list of persons from the collection.

So, try using these methods and if any let me know.
Happy coding...




Sunday, May 3, 2020

C# Mongodb Data Access Layer

As we have discussed in our previous post, lets focus on a working data access layer that we can use for our mongodb database.

As a collection based database, it's a bit different as how we should deal with records (collections) here. Let's have a look at the code.

 public class MongoDBCRUD  
   {  
     MongoClient client;  
     private IMongoDatabase mongoDatabase;  
     string DBMaster, DBName;  
     public MongoDBCRUD()  
     {  
     }  
     public MongoDBCRUD(string MasterDatabase)  
     {  
       DBMaster = MasterDatabase;  
     }  
     private void Connect()  
     {        
       DBName = DBMaster ?? (Common.DBName != null ? Common.DBName.ToString() : string.Empty);  
       if (!string.IsNullOrEmpty(Common.ConString))  
         client = new MongoClient(Common.ConString);  
       if (!string.IsNullOrEmpty(DBName))  
         mongoDatabase = client.GetDatabase(DBName);  
     }  
     public bool Insert<T>(T RecordToInsert)  
     {  
       return Insert<T>(typeof(T).Name, RecordToInsert);  
     }  
     public bool Insert<T>(string TableName, T RecordToInsert)  
     {  
       Connect();  
       var collection = mongoDatabase.GetCollection<T>(TableName);  
       collection.InsertOne(RecordToInsert);  
       return true;  
     }  
     public bool Replace<T>(T RecordToUpsert, string UpdateColumnName, BsonValue WhereValue)  
     {  
       return Replace<T>(typeof(T).Name, RecordToUpsert, UpdateColumnName, WhereValue);  
     }  
     public bool Replace<T>(string TableName, T RecordToUpsert, string UpdateColumnName, BsonValue WhereValue)  
     {  
       Connect();  
       var filter = Builders<T>.Filter.Eq(UpdateColumnName, WhereValue);        
       var collection = mongoDatabase.GetCollection<T>(TableName);        
       var result = collection.ReplaceOne(filter, RecordToUpsert);  
       return result.IsAcknowledged;  
     }  
     public void Delete<T>(BsonValue WhereValue)  
     {  
       Delete<T>(typeof(T).Name, "_id", WhereValue);  
     }  
     public void Delete<T>(string DeleteColumnName, BsonValue WhereValue)  
     {  
       Delete<T>(typeof(T).Name, DeleteColumnName, WhereValue);  
     }      
     public void Delete<T>(string TableName, string DeleteColumnName, BsonValue WhereValue)  
     {  
       Connect();  
       var collection = mongoDatabase.GetCollection<T>(TableName);  
       var filter = Builders<T>.Filter.Eq(DeleteColumnName, WhereValue);  
       collection.DeleteOne(filter);  
     }  
     public List<T> Select<T>()  
     {  
       return Select<T>(typeof(T).Name);  
     }  
     public List<T> Select<T>(string TableName)  
     {  
       Connect();  
       var collection = mongoDatabase.GetCollection<T>(TableName);  
       return collection.Find(new BsonDocument()).ToList();  
     }  
     public List<T> Select<T>(BsonValue WhereValue, string SelectColumnName = null)  
     {  
       Connect();  
       if (string.IsNullOrEmpty(SelectColumnName))  
         SelectColumnName = "_id";  
       return Select<T>(typeof(T).Name, SelectColumnName, WhereValue);  
     }  
     public List<T> Select<T>(string TableName, string SelectColumnName, BsonValue WhereValue)  
     {  
       Connect();  
       var collection = mongoDatabase.GetCollection<T>(TableName);  
       var filter = Builders<T>.Filter.Eq(SelectColumnName, WhereValue);  
       return collection.Find(filter).ToList();  
     }      
     public T Select<T>(Dictionary<string, BsonValue> WhereValue)  
     {  
       return Select<T>(typeof(T).Name, WhereValue);  
     }  
     public T Select<T>(string TableName, Dictionary<string, BsonValue> WhereValue)  
     {  
       Connect();  
       var collection = mongoDatabase.GetCollection<T>(TableName);  
       FilterDefinition<T>[] filterDefinition = new FilterDefinition<T>[WhereValue.Count];  
       FilterDefinition<T> filter;  
       int i = 0;  
       foreach (var v in WhereValue)  
       {  
         filter = Builders<T>.Filter.Eq(v.Key, v.Value);  
         filterDefinition[i] = filter;  
         i++;  
       }  
       return collection.Find(Builders<T>.Filter.And(filterDefinition)).FirstOrDefault();  
     }  
     public int GetNextNumber<T>()  
     {  
       Connect();  
       var TableName = typeof(T).Name;  
       var value = this.Select<AutoIncrement>().Where(x => x.Table.Equals(TableName)).ToList().FirstOrDefault();  
       if (value == null)  
         return 1;  
       else  
         return value.TableId + 1;  
     }  
     public void SetNextNumber<T>(T Table, int id)  
     {  
       Connect();  
       var TableName = typeof(T).Name;  
       AutoIncrement autoIncrement = new AutoIncrement() { TableId = id, Table = TableName };  
       if (id > 1)  
       {   
         var filter = Builders<AutoIncrement>.Filter.Eq("Table", TableName);  
         var update = Builders<AutoIncrement>.Update.Set("TableId", id);  
         var collection = mongoDatabase.GetCollection<AutoIncrement>("AutoIncrement");  
         var result = collection.UpdateOne(filter, update);  
       }  
       else  
         this.Insert<AutoIncrement>(autoIncrement);        
     }  
   }  


You can copy this class and use it directly in your application. Anyway, it's got few more functions as you can have a parent and child database connections with primary keys as a value added function.

In our next post, we will talk a bit more about individual functions.
till that play with this code.

happy coding.

Friday, April 17, 2020

Writing Data Access Layer in C# for MongoDB

As discussed from our previous post, MongoDB is pretty good if we can work it in int's unique way. So, to do all of the work, we need to have a propert DB layer. Let's first look at how we can connect and then do a sample select.

 var client = new MongoClient("mongodb://localhost:27017");  
 mongoDatabase = client.GetDatabase("TemplateManager");  
 public List<T> Select<T>(string TableName, string SelectColumnName, BsonValue WhereValue)  
     {  
       var collection = mongoDatabase.GetCollection<T>(TableName);  
       var filter = Builders<T>.Filter.Eq(SelectColumnName, WhereValue);  
       return collection.Find(filter).ToList();  
     }    

Using above code, you can connect to the locally installed DB server get a list of records which can be converted into a list of entity.

Lets see how this is used.

 List<Person> personList = new bllPerson().Select();  

The Person is an entity which we use in the collection. The bllPerson is a class that handles DB calls. So it gets all the people saved under Person collection in the Database.

Try it and next time lets talk about Updated and Delete method.

Happy coding.

Sunday, April 5, 2020

Using MongoDB for your .Net applications - Data Access (Layer)

Hopefully you might have worked on MongoDB or probably not. Anyway, MongoDB can be downloaded https://www.mongodb.com/download-center/community here. It's the community version and free version. Install and run the server. It runs on localhost:27017.

If you want to know more about what is MongoDB, visit here https://www.mongodb.com/what-is-mongodb


When you download the server and install, you can easily do all the CRUD operations. for that you need to install the MongoDB nuget package. Those have the necessary dlls to perform database actions. following are the packages you need to install.


Once you have it, you can reference the namespaces.



So, you now you are ready to write your own codes to deal with MongoDB. For example, you can think of the following code.























This is how you can get this to use in your front end.





try to understand the basics here. documentation of MongoDB is here (https://developer.mongodb.com/learn?languages=C%23)

Next time, lets see how we can write our own Data Access Layer.

Until that, happy coding.

Tuesday, March 31, 2020

MS Sql Server - Alternative to Cursor

Hello Friends,

If you are working with MS SQL Server, you may familier with Cursor which we use to loop through a recordset. But as everyone knows, cursors are expensive. They consume more memory and also take more time.

So lets discuss how to avoid cursors but how to loop as we use a cursor.

Create a temp table.
 create table #ttProduct (  
      [id] int identity(1,1) NOT NULL,  
      [idProduct] inIdentifier not null,       
      [idCategory] inIdentifier not null, ...etc  

and here we get selected records into the temp table.
 insert #ttProduct(  
 [idProduct],   
 [idCategory],   
 [lbCategory],  
 .  
 .  
 )  
 select   
      cp.idProduct,  
      po.idCategory,  
      cat.ShortName AS 'lbCategory',  
 .  
 .  

And now let's see how it is done.
 while exists (select * from #ttProduct)  
           begin  
                select top 1 @recordId = id, @idProduct=idProduct  
                from #ttProduct  
                order by id asc  
                --select * from #ttProduct where id = @recordId  
                -- Do something with your TableID  
                delete #ttProduct  
                where id = @recordId  
           end  
 drop table #ttProduct  

it is basically a while loop and each iteration we delete the top record once processed. So it will ultimately run out from records. End of everything, drop the tempory table too.

Hope you have got your idea.

Friday, March 27, 2020

c# method to return dynamic types

This is a simple method that return dynamic types based on what it recieves from the parameter.

 private dynamic GetValue<T>(object value, bool toString)  
     {  
       Type type = typeof(T);  
       if (value == null || (value != null && string.IsNullOrEmpty(value.ToString())))  
       {  
         if (toString)  
           return string.Empty;  
         else  
           return null;  
       }  
       else  
       {  
         if (toString)  
           return value.ToString();  
         else  
           return Convert.ChangeType(value, type);  
       }  
     }  

value : the value you want to get
toString : whether the return type needs to be as a string.

example,
 item.EXT_PRODUCT_ID = this.GetValue<int?>(p.idProduct, true);  

The value we pass is
p.idProduct

and it is a nullable integer. Also we set toString as true. so the return value is :
"466565" or empty string.

Instead of checking null everytime, we can use this method.

Happy coding.

Friday, March 20, 2020

Multithreading - passing parameters

    When you need to write multithreading application, you might need to pass parameters to the method that is executed by another thread. Sometimes, assigining the value to a variable and access it from the method works but what if it's countless threads that access the same method. 

You can directly pass the values to the parameter. Look at the below code.


This is the method that needs to be executed by another thread. (Actually a loop of threads). This is how it can be done.


k.Key is the keyword and v is the url.

This way you can pass parameters and will not be effected to any thread.

Happy coding..