Work with Elasticsearch Data in FoxPro

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The Elasticsearch ODBC Driver is a powerful tool that allows you to connect with live Elasticsearch document databases, directly from any applications that support ODBC connectivity.

Access Elasticsearch like you would a database - read, write, and update through a standard ODBC Driver interface.

Load Elasticsearch data into a FoxPro database. This article includes full code and a walk-through of the process.

The CData ODBC Driver for Elasticsearch enables you to access Elasticsearch data using the ODBC standard. You can use the CData ODBC Driver for Elasticsearch to integrate Elasticsearch data into your FoxPro project. The procedure below provides a walk-through of the included code sample, which saves Elasticsearch data into tables in a FoxPro database.

Connect to Elasticsearch as an ODBC Data Source

If you have not already, first specify connection properties in an ODBC DSN (data source name). This is the last step of the driver installation. You can use the Microsoft ODBC Data Source Administrator to create and configure ODBC DSNs.

NOTE: Set the 'Map To WVarchar' connection property to FALSE (FoxPro uses the ODBC W API and returns the WCHAR for the value type).

Set the Server and Port connection properties to connect. To authenticate, set the User and Password properties, PKI (public key infrastructure) properties, or both. To use PKI, set the SSLClientCert, SSLClientCertType, SSLClientCertSubject, and SSLClientCertPassword properties.

The data provider uses X-Pack Security for TLS/SSL and authentication. To connect over TLS/SSL, prefix the Server value with 'https://'. Note: TLS/SSL and client authentication must be enabled on X-Pack to use PKI.

Once the data provider is connected, X-Pack will then perform user authentication and grant role permissions based on the realms you have configured.

Connect and Transfer

To get started, add the code sample to a new project. You can execute the following command to save all tables without displaying them:

DO C:\Temp\sqldump.prg WITH "CData Elasticsearch Source", "TESTDB", .f.

Below is the process that the program follows:

Create a new FoxPro database.
Open a connection to Elasticsearch data with the line below:
m.hSQLconnection = SQLCONNECT(m.cODBCDSN)
If the connection was successful, you can now retrieve the list of tables using the SQLTABLES function. The code below saves the list of tables in sys_tables.dbf:
WAIT WINDOW "Fetching tables for data source '" + m.cODBCDSN + "'..." NOWAIT NOCLEAR m.nSQLTABLES = SQLTABLES(m.hSQLconnection) IF lUseDistinctConnections WAIT WINDOW "Closing ODBC Connection for data source '" + m.cODBCDSN + "'..." NOWAIT NOCLEAR SQLDISCONNECT(m.hSQLconnection) m.hSQLconnection = 0 * SQLCONNECT needs to be called again ENDIF IF m.nSQLTABLES > 0 * create local table containing list of tables in db COPY TO (m.cImportData + "sys_tables") USE * convert each table to DBF USE (m.cImportData + "sys_tables") ALTER TABLE DBF("sys_tables") ; ADD COLUMN records i ; ADD COLUMN dbfname m
Scan over each table, saving it to a DBF file. The function ODBCtoDBF stores the table in a DBF file and then opens a grid if the lBrowse parameter is set to true: FUNCTION ODBCtoDBF (cTableName as String, cTableType as String, lBrowse as Logical, lhSQLConnection as Integer) WAIT WINDOW ; "Converting " + m.cTableType + ' "' + m.cTableName + '" to DBF...' ; NOWAIT NOCLEAR ACTIVATE SCREEN * strip characters incompatible with FoxPro out of the name of the DBF file m.cTableAlias = "" m.nTableNameLen = LEN(m.cTableName) m.nTableNameStart = 1 FOR m.nTableNameStart = 1 TO m.nTableNameLen m.cCharacter = SUBSTR(m.cTableName, m.nTableNameStart, 1) IF !ISALPHA(m.cCharacter) .and. (m.nTableNameStart = 1 .or. !ISDIGIT(m.cCharacter)) m.cTableAlias = m.cTableAlias + "_" ELSE m.cTableAlias = m.cTableAlias + m.cCharacter ENDIF ENDFOR m.cFromTable = m.cTableName m.cTempViewAlias = m.cTableType + "_" + m.cTableAlias LOCAL loException as Exception LOCAL lnResultSets TRY * run query m.lnResultSets = SQLEXEC(m.lhSQLConnection, ; "SELECT * FROM " + m.cFromTable, ; m.cTempViewAlias, ; aSQLResult) IF m.lnResultSets#1 SET STEP ON ENDIF ACTIVATE SCREEN CATCH TO m.loException ACTIVATE SCREEN ? "Error opening " + m.cTempViewAlias + ":" ? m.loException.Message ? m.loException.Details ENDTRY IF !USED(m.cTempViewAlias) RETURN ENDIF * copy records from view cursor to disk SELECT * FROM (m.cTempViewAlias) ; INTO TABLE (m.cImportData + m.cTableAlias) IF USED(m.cTableAlias) ACTIVATE SCREEN FLUSH && flush the buffer to write the data to disk IF m.lBrowse * pop the table up on screen SELECT (m.cTableAlias) BROWSE NORMAL NOMODIFY NOWAIT ACTIVATE SCREEN ELSE * close on-disk table for now USE IN (m.cTableAlias) ACTIVATE SCREEN ENDIF ENDIF IF USED(m.cTempViewAlias) USE IN &cTempViewAlias && close SQL view ACTIVATE SCREEN ENDIF WAIT CLEAR ENDFUNC
You can now save tables of Elasticsearch data as DBF files.

Below is the full code, in FoxPro 9 syntax:


PARAMETERS cODBCDSN, cDatabaseName, lBrowseAfterConvert

*	cODBCDSN				The ODBC data source name, used for the name of the folder where the DBF tables are stored.
*	cDatabaseName			The name of the FoxPro database to use. This database is created if it does not exist. The default is DATABASE_NAME.
*								
*	lBrowseAfterConvert		If ".t." display each table with the BROWSE command after importing it. If ".f." close each table before moving on to the next one.

#define		ODBC_DATASOURCE		"DataSourceName"
#define		DATABASE_NAME		"odbcdata"

m.m_tpath = ".\"                && root directory for data

ON ERROR
SET SAFETY OFF

IF VARTYPE(m.cODBCDSN)#"C" .or. EMPTY(m.cODBCDSN)
  m.cODBCDSN = ODBC_DATASOURCE
ENDIF
IF VARTYPE(m.cDatabaseName)#"C" .or. EMPTY(m.cDatabaseName)
  m.cDatabaseName = DATABASE_NAME
ENDIF

m.cImportData = m.cODBCDSN + "\"

CLOSE TABLES ALL
CLOSE DATABASES ALL

IF !DIRECTORY(m.cImportData)
	MKDIR (m.cImportData)
ENDIF

CREATE DATABASE (m.cDatabaseName)
CREATE CONNECTION (m.cDatabaseName) DATASOURCE (m.cODBCDSN) DATABASE (m.cDatabaseName)

WAIT WINDOW "Opening ODBC Connection for data source '" + m.cODBCDSN + "'..." NOWAIT NOCLEAR
m.hSQLconnection = SQLCONNECT(m.cODBCDSN)

IF m.hSQLconnection > 0
  * Connection successful; get list of tables
  WAIT WINDOW "Fetching tables for data source '" + m.cODBCDSN + "'..." NOWAIT NOCLEAR
  m.nSQLTABLES = SQLTABLES(m.hSQLconnection)

  IF m.nSQLTABLES > 0
    * Create local table containing list of tables in db
    COPY TO (m.cImportData + "sys_tables")
    USE

    * Convert each table to DBF
    USE (m.cImportData + "sys_tables")
    ALTER TABLE DBF("sys_tables") ;
    ADD COLUMN records	i ;
    ADD COLUMN dbfname	m

    SCAN	
    m.cCurrentTable	= TRIM(sys_tables.table_name)
    m.cCurrentTableType	= TRIM(sys_tables.table_type) && Valid values are "SYSTEMTABLE", "TABLE", and "VIEW".
    IF m.cCurrentTableType = "TABLE" or m.cCurrentTableType = "VIEW"

      ODBCtoDBF(m.cCurrentTable, m.cCurrentTableType, m.lBrowseAfterConvert, m.hSQLConnection)
    ELSE
      ACTIVATE SCREEN
      ? "ERROR:", m.cCurrentTable, "Couldn't open ODBC connection."
      =MESSAGEBOX("couldn't open data source " + m.cODBCDSN + " for table " + m.cCurrentTable + ".")
    ENDIF

    ENDSCAN
    BROWSE NORMAL NOWAIT

  ELSE
    =MESSAGEBOX("No tables found in data source " + m.cODBCDSN + ".")
    SET STEP ON
  ENDIF
  
  SQLDISCONNECT(m.hSQLconnection)
  
ELSE
  =MESSAGEBOX("Could not open data source " + m.cODBCDSN + ".")
  SET STEP ON
ENDIF

FUNCTION ODBCtoDBF (cTableName as String, cTableType as String, lBrowse as Logical, lhSQLConnection as Integer)

  WAIT WINDOW ;
  "Converting " + m.cTableType + ' "' + m.cTableName + '" to DBF...' ;
  NOWAIT NOCLEAR

  ACTIVATE SCREEN

  * Strip characters incompatible with FoxPro out of the name of the DBF file
  m.cTableAlias		= ""
  m.nTableNameLen		= LEN(m.cTableName)
  m.nTableNameStart	= 1
  
  FOR m.nTableNameStart = 1 TO m.nTableNameLen
    m.cCharacter = SUBSTR(m.cTableName, m.nTableNameStart, 1)	
    IF !ISALPHA(m.cCharacter) .and. (m.nTableNameStart = 1 .or. !ISDIGIT(m.cCharacter))
      m.cTableAlias = m.cTableAlias + "_"
    ELSE
      m.cTableAlias = m.cTableAlias + m.cCharacter
    ENDIF
  ENDFOR

  m.cFromTable = m.cTableName
  m.cTempViewAlias	= m.cTableType + "_" + m.cTableAlias

  LOCAL loException as Exception
  LOCAL lnResultSets
  
  TRY
    * Run query
    m.lnResultSets = SQLEXEC(m.lhSQLConnection, ;
      "SELECT * FROM " + m.cFromTable, ;
      m.cTempViewAlias, ;
      aSQLResult)
	  
    IF m.lnResultSets#1
      SET STEP ON
    ENDIF
	
    ACTIVATE SCREEN

  CATCH TO m.loException
    ACTIVATE SCREEN
    ? "Error opening " + m.cTempViewAlias + ":"
    ? m.loException.Message
    ? m.loException.Details
  ENDTRY

  IF !USED(m.cTempViewAlias)
    RETURN
  ENDIF

  * Copy records from view cursor to disk
  SELECT * FROM (m.cTempViewAlias) ;
    INTO TABLE (m.cImportData + m.cTableAlias)

  IF USED(m.cTableAlias)

    ACTIVATE SCREEN

    FLUSH	&& Flush the buffer to write the data to disk

    IF m.lBrowse
      * Display the table on screen
      SELECT (m.cTableAlias)
      BROWSE NORMAL NOMODIFY NOWAIT
      ACTIVATE SCREEN
    ELSE
      * Close on-disk table
      USE IN (m.cTableAlias)
      ACTIVATE SCREEN
    ENDIF
  ENDIF

  IF USED(m.cTempViewAlias)
    USE IN &cTempViewAlias && Close SQL view
    ACTIVATE SCREEN
  ENDIF

  WAIT CLEAR

ENDFUNC

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Work with Elasticsearch Data in FoxPro

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Connect and Transfer