Write a Simple Go Application to work with Greenhouse Data on Linux

Use CData ODBC drivers and unixODBC to create a simple Go app with live connectivity to Greenhouse data.

Go is an open source programming language that enables you to easily build software on Linux/UNIX machines. When Go is paired with the ODBC Driver for Greenhouse and unixODBC you are able write applications with connectivity to live Greenhouse data. This article will walk you through the process of installing the ODBC Driver for Greenhouse, configuring a connection using the unixODBC Driver Manager, and creating a simple Go application to work with Greenhouse data.

Using the CData ODBC Drivers on a Unix/Linux Machine

The CData ODBC Drivers are supported in various Red Hat-based and Debian-based systems, including Ubuntu, Debian, RHEL, CentOS, and Fedora. There are also several libraries and packages that are required, many of which may be installed by default, depending on your system. For more information on the supported versions of Linux operating systems and the required libraries, please refer to the "Getting Started" section in help documentation (installed and found online).

Installing the Driver Manager

Before installing the driver, you need to be sure that your system has a driver manager. For this article, you will use unixODBC, a free and open source ODBC driver manager that is widely supported.

For Debian-based systems like Ubuntu, you can install unixODBC with the APT package manager:


apt-get install unixodbc unixodbc-dev

For systems based on Red Hat Linux, you can install unixODBC with yum or dnf:


yum install unixODBC unixODBC-devel

The unixODBC driver manager reads information about drivers from an odbcinst.ini file and about data sources from an odbc.ini file. You can determine the location of the configuration files on your system by entering the following command into a terminal:


odbcinst -j

NOTE: You may need to install odbcinst. Use the following command in a terminal:


apt install odbcinst

The output of the command will display the locations of the configuration files for ODBC data sources and registered ODBC drivers. User data sources can only be accessed by the user account whose home folder the odbc.ini is located in. System data sources can be accessed by all users. Below is an example of the output of this command:


DRIVERS............: /etc/odbcinst.ini
SYSTEM DATA SOURCES: /etc/odbc.ini
FILE DATA SOURCES..: /etc/ODBCDataSources
USER DATA SOURCES..: /home/myuser/.odbc.ini
SQLULEN Size.......: 8
SQLLEN Size........: 8
SQLSETPOSIROW Size.: 8

Installing the Driver

You can download the driver in standard package formats: the Debian .deb package format or the .rpm file format. Once you have downloaded the file, you can install the driver from the terminal.

The driver installer registers the driver with unixODBC and creates a system DSN, which can be used later in any tools or applications that support ODBC connectivity.

For Debian-based systems like Ubuntu, run the following command with sudo or as root: dpkg -i /path/to/package.deb

For systems that support .rpms, run the following command with sudo or as root: rpm -i /path/to/package.rpm

Once the driver is installed, you can list the registered drivers and defined data sources using the unixODBC driver manager:

List the Registered Driver(s)


odbcinst -q -d
CData ODBC Driver for Greenhouse
...

List the Defined Data Source(s)


odbcinst -q -s
CData Greenhouse Source
...

To use the CData ODBC Driver for Greenhouse with unixODBC, you need to ensure that the driver is configured to use UTF-16. To do so, edit the INI file for the driver (cdata.odbc.greenhouse.ini), which can be found in the lib folder in the installation location (typically /opt/cdata/cdata-odbc-driver-for-greenhouse), as follows:

cdata.odbc.greenhouse.ini


...

[Driver]
DriverManagerEncoding = UTF-16

Modifying the DSN

When the driver is installed, a system DSN should be predefined. You can modify the DSN by editing the system data sources file (/etc/odbc.ini) and defining the required connection properties. Additionally, you can create user-specific DSNs that will not require root access to modify in $HOME/.odbc.ini.

You need an API key to connect to Greenhouse. To create an API key, follow the steps below:

Click the Configure icon in the navigation bar and locate Dev Center on the left.
Select API Credential Management.
Click Create New API Key.

Set "API Type" to Harvest.
Set "Partner" to custom.
Optionally, provide a description.

Proceed to Manage permissions and select the appropriate permissions based on the resources you want to access through the driver.
Copy the created key and set APIKey to that value.

/etc/odbc.ini or $HOME/.odbc.ini


[CData Greenhouse Source]
Driver = /opt/cdata/cdata-odbc-driver-for-greenhouse/lib/libgreenhouseodbc.x64.so
Description = My Description
APIKey = YourAPIKey

For specific information on using these configuration files, please refer to the help documentation (installed and found online).

Creating a Simple Go App for Greenhouse Data

With the Driver Manager installed and the DSN configured, you are ready to create a simple Go application to work with your Greenhouse data. To start, install a Go driver for ODBC databases. While there are several options available, this article will use the odbc driver found at https://github.com/alexbrainman/odbc.

Installing ODBC on Linux

There are a series of steps required to install the ODBC driver for Go.

Create the $HOME/golang/go path (if it does not exist) by entering the following commands in a terminal: mkdir /root/golang mkdir /root/golang/go
Define the GOPATH environment variable: export GOPATH=$HOME/golang/go
Create a module inside the new Go directory: cd $GOPATH go mod init myproject
Install the Go driver for ODBC databases:
go get http://github.com/alexbrainman/odbc

Now you are ready to create and execute a simple Go application.

Sample Go Application

The sample application issues a simple SQL SELECT query for Greenhouse data and displays the results. Create the directory $GOPATH/src/cdata-odbc-greenhouse and create a new Go source file, copying the source code from below.

cdata-odbc-greenhouse.go


package main

import (
  _ "github.com/alexbrainman/odbc"
  "database/sql"
  "log"
  "fmt"
)

func main() {
  db, err := sql.Open("odbc",
    "DSN=CData Greenhouse Source")
  if err != nil {
    log.Fatal(err)
  }

  var (
    id string
    candidateid string
  )

  rows, err := db.Query("SELECT Id, CandidateId FROM Applications WHERE Status = ?", "Active")
  if err != nil {
    log.Fatal(err)
  }
  defer rows.Close()
  for rows.Next() {
    err := rows.Scan(&id, &candidateid)
    if err != nil {
      log.Fatal(err)
    }
    fmt.Println(id, candidateid)
  }
  err = rows.Err()
  if err != nil {
    log.Fatal(err)
  }

  defer db.Close()
}

In the terminal, navigate to the Go application directory and build the application:


go build

After the application builds, you will be able to execute the application, displaying your Greenhouse data:


./cdata-odbc-greenhouse

At this point, you have a simple Go application for working with Greenhouse data. From here, you can easily expand the application, adding deeper read functionality through familiar SQL queries.

Ready to get started?

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

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Learn more:

Greenhouse ODBC Driver

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

Access Greenhouse data like you would a database - read, write, and update Greenhouse 0, etc. through a standard ODBC Driver interface.

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