B4J Library [SithasoMongoDB] A jMongo class helper for everything MongoDB CRUD

Hi there

This helper class is to help anyone explore the jMongo library for CRUD for the less adventurous. Demo attached.

SithasoMongoDB

• Initialize (sHost As String, iPort As Int, dbName As String, tblName As String) As SithasoMongoDB
  '
  'initialize the class
  Dim dbMongo As SithasoMongoDB
  dbMongo.Initialize("127.0.0.1", 27017, "test", "users")
• PrepareRecord As SithasoMongoDB
  prepare the record for insert/update
• SetField (fld As String, value As Object) As SithasoMongoDB
  set a field on the record
• SetLimit (l As Int) As SithasoMongoDB
  set limit
• SetSkip (l As Int) As SithasoMongoDB
  set skip
• MoveFirst
  movefirst
• MoveLast
  movelast
• MovePrevious
  moveprevious
• MoveNext
  movenext
• ClearWhere As SithasoMongoDB
  clear where clause
• AddFields (flds As List) As SithasoMongoDB
  add projection
• AddSort (fld As String, desc As Boolean) As SithasoMongoDB
  add a sort order
• AddWhere (fld As String, operator As String, value As Object) As SithasoMongoDB
  add a where clause for your select where statement
  _id will be ignored
• Update As Int
  
  'update a record, returns number of records updated
  'you can specify a where clause optionally
  'dbConnect.ClearWhere
  'dbConnect.AddWhere("name", dbConnect.EQ_OP, "Anele")
  dbConnect.PrepareRecord
  dbConnect.SetField("age", 50)
  dbConnect.SetField("work", "Software Engineer")
  dbConnect.Update
  if dbConnect.RowCount >= 1 then
  'the records were updated
  end if
• Delete (id As String) As Int
  
  'delete record and returns number of records deleted
  dbMongo.Delete("1234567")
  if dbMongo.RowCount = 1 then
  'the record was deleted
  end if
• DeleteWhere As Int
  
  'delete record by id or where clause returns number of records deleted
  'dbConnect.ClearWhere
  'dbConnect.AddWhere("name", dbConnect.EQ_OP, "Anele")
  dbMongo.DeleteWhere
  if dbMongo.RowCount = 1 then
  'the record was deleted
  end if
• DeleteAll As Int
  
  'delete all records
  dbMongo.DeleteAll
  if dbMongo.RowCount > 0 then
  'the records were deleted
  end if
• Read (id As String) As Map
  
  'read record by id, get result
  dbMongo.Read("1234567")
  if dbMongo.RowCount = 1 then
  'the record was read
  'dbConnect.MoveFirst
  dim sname As String = dbMongo.GetString("name")
  log(sname)
  end if
• Insert
  
  'insert record, returns the number of records inserted
  '_id will be ignore
  dbMongo.PrepareRecord
  dbMongo.SetField("name", "Anele")
  dbMongo.SetField("email", "[EMAIL][email protected][/EMAIL]")
  dbConnect.Insert
• SelectAll() As List
  
  'select where records and show specific fields
  dbConnect.ClearWhere
  dbConnect.AddFields(array("name", "lastname", "_id"))
  dbConnect.AddWhere("name", dbConnect.EQ_OP, "Anele")
  dbConnect.SetSkip(1)
  dbConnect.SetLimit(1)
  dbConnect.SelectAll
  if dbConnect.RowCount >= 1 then
  'the records were selected
  end if
• setPosition (pos As Int)
  set the position of the current record
• GetInt (fld As String) As Int
  get an integer from the current record
• GetLong (fld As String) As Long
  get a long from the current record
• GetID As String
  get the id of this record
• GetString (fld As String) As String
  get a string from the current record
• GetBoolean (fld As String) As Boolean
  get a boolean from the current record
• GetDouble (fld As String) As Double
  get a double from the current record

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[Mashiane]

Let me explain.

The C in CRUD

Lets initialize the helper class and add some records. We create a family database and a members table.

Dim smongo As SithasoMongoDB
    'create a database named family with a table named members
    smongo.Initialize("127.0.0.1", 27017, "family", "members")
    'create the record to add
    Log("INSERT RECORD...")
    smongo.PrepareRecord
    smongo.SetField("firstname", "Anele")
    smongo.SetField("lastname", "Mbanga")
    smongo.SetField("gender", "Male")
    smongo.Insert

 

[Mashiane]

The R in CRUD

In this example, (well we dont have an id we know of, so we will select the records, move to the last record added, get its _id and then read that.

Getting the last record added

'* get the last record
    smongo.ClearWhere
    smongo.SelectAll
    smongo.MoveLast
    Dim id As String = smongo.GetID
    Log(id)

Now lets read that record using that ID.

'read a record using id
    smongo.Read(id)
    Log(smongo.RowCount & " record(s) read!")
    If smongo.RowCount = 1 Then
        smongo.MoveFirst
        Dim sname As String = smongo.GetString("firstname")
        Log(sname)
        Log(smongo.Record)
    End If

 

[Mashiane]

The U in CRUD

In this example, we use the last read id we got in the previous post. We then update the lastname and the age of the person.

'update an existing record by _id
    smongo.PrepareRecord
    smongo.SetField("_id", id)
    smongo.SetField("lastname", "Nguta")
    smongo.SetField("age", 52)
    smongo.Update
    Log(smongo.RowCount & " record(s) updated!")

We can also execute something like "UPDATE WHERE..." like this

Log("UPDATE RECORD...")
    smongo.ClearWhere
    'update where firstname = anele
    smongo.AddWhere("firstname", smongo.EQ_OP, "Anele")
    smongo.PrepareRecord
    'set these fields
    smongo.SetField("work", "Software Engineer")
    smongo.SetField("age", 51)
    smongo.Update
    Log(smongo.RowCount & " record(s) updated!")

This finds all records where the first name = "Anele", then the work and age fields are updated.

Using the same approach, you can also include fields that didnt exist before. Here we update all Males and add a "loves" field.

'update where
    Log("UPDATE WHERE")
    smongo.ClearWhere
    smongo.AddWhere("gender", smongo.EQ_OP, "Male")
    smongo.PrepareRecord
    smongo.SetField("loves", "b4x")
    smongo.Update
    Log(smongo.RowCount & " record(s) updated!")

 

[Mashiane]

The D in CRUD

In this example, we execute a delete and a delete where. To delete a single record, just like before...

We get the last id added to the table... (just to demonstrate) and then use that id to delete our record of interest.

smongo.ClearWhere
    smongo.SelectAll
    smongo.MoveLast
    Dim lastID As String = smongo.GetID
    Log(lastID)
    smongo.Delete(lastID)
    Log(smongo.RowCount & " record(s) deleted.")

We can also execute a "DELETE WHERE..."

smongo.ClearWhere
    smongo.AddWhere("age", smongo.EQ_OP, 52)
    smongo.DeleteWhere
    Log(smongo.RowCount & " record(s) deleted.")

And perhaps a "TRUNCATE TABLE ..." to delete all records

smongo.DeleteAll
    Log(smongo.RowCount & " record(s) deleted.")

 

[Mashiane]

We can also SELECT WHERE ... ORDER BY .... LIMIT.... OFFSET...

smongo.ClearWhere
    smongo.AddSort("surname", True)
    smongo.SetLimit(5)
    smongo.SetSkip(1)
    smongo.SelectAll
    Log(smongo.RowCount & " record(s) selected!")
    For Each rec As Map In smongo.result
        Log(rec)
    Next

Here we select all records, sorted by surname in descending order, with a limit of 5 and an offset of 1

 

[Mashiane]

Of just a basic SELECT WHERE statement

smongo.ClearWhere
    smongo.AddFields(Array("_id", "firstname", "lastname", "age"))
    smongo.AddWhere("age", smongo.EQ_OP, 52)
    smongo.SelectAll
    Log(smongo.RowCount & " record(s) selected!")
    For Each rec As Map In smongo.result
        Log(rec)
    Next

Here we use a projection to only show _id, firstname, lastname and age fields. Only these fields will be shown even if records have more fields.
We select all records where the age is 52

See the attached demo for more details.

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