Work with Elasticsearch Data in FoxPro



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.

About Elasticsearch Data Integration

Accessing and integrating live data from Elasticsearch has never been easier with CData. Customers rely on CData connectivity to:

  • Access both the SQL endpoints and REST endpoints, optimizing connectivity and offering more options when it comes to reading and writing Elasticsearch data.
  • Connect to virtually every Elasticsearch instance starting with v2.2 and Open Source Elasticsearch subscriptions.
  • Always receive a relevance score for the query results without explicitly requiring the SCORE() function, simplifying access from 3rd party tools and easily seeing how the query results rank in text relevance.
  • Search through multiple indices, relying on Elasticsearch to manage and process the query and results instead of the client machine.

Users frequently integrate Elasticsearch data with analytics tools such as Crystal Reports, Power BI, and Excel, and leverage our tools to enable a single, federated access layer to all of their data sources, including Elasticsearch.

For more information on CData's Elasticsearch solutions, check out our Knowledge Base article: CData Elasticsearch Driver Features & Differentiators.


Getting Started


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:

  1. Create a new FoxPro database.
  2. Open a connection to Elasticsearch data with the line below:

    m.hSQLconnection = SQLCONNECT(m.cODBCDSN)
    
  3. 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
    
  4. 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
    
  5. 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

Ready to get started?

Download a free trial of the Elasticsearch ODBC Driver to get started:

 Download Now

Learn more:

Elasticsearch Icon Elasticsearch ODBC Driver

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.