Exposing a Google Spreadsheet as a Data Service

This tutorial will guide you on how to expose data in a google spreadsheet as a data service in WSO2 Data Services Server.

See the following topics for instructions:

Now, let's start creating the data service from scratch:

1. Log in to the management console using the following URL on your browser:  "https://localhost:9443/carbon/".

2. Click Create under the Data Service menu to open the Create Data Service wizard.

3. Enter GSpread as the data service name as shown below. Leave the default values for the other fields.
   

4. Click Next to go to the Datasources screen.
   

You can add a google spreadsheet as the datasource by following the steps given below.

1. Click Add New Datasource to open the following screen.
   

2. Follow the instructions below to fill the datasource details.

   1. In the Datasource Id field, enter GoogleSpreadsheet as the value.

   2. In the Datasource Type field, specify the type of datasource for which the data service is created. Select Google Spreadsheet from the list. You will now get the following screen:
      

   3. In the Google Spreadsheet URL field, specify the path to your spreadsheet. The file we are using for this tutorial is https://spreadsheets.google.com/ccc?key=0Av5bU8aVtFjPdElrUVN3VmZlRkoyM1ZzVlE1MzdtbXc&hl=en.

   4. Select a value for the Visibility field based on whether the spreadsheet is private or public. Since we have used a private spreadsheet in this example, set the visibility to Private. You are asked to provide credentials as well as a browser redirect URL that is known to your browser. Google no longer supports authentication through username and password. Therefore, it is now necessary to provide credentials in the form of a Client ID, Client Secret and Refresh Token as shown below.
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   5. See the google documentation for instructions on how to get an OAuth2 client ID and client secret. In order to get these credentials, you will be asked to provide an authorization redirect URL. Be sure to use the same URL as the browser redirect URL shown above.

   6. Update the Client ID and the Client Secret fields in the Edit Datasource screen with the values you got in the previous step:
      

   7. Click Generate Token. You will now be redirected to the google consent page. After you approve that, the refresh token will be inserted into the New Datasource screen automatically as shown below. Note that we just store the refresh token because the access token is going to expire anyway.
      

   8. The Use Query Mode option allows you to write queries for the spreadsheet in two different modes:

      • Non-Query mode: Allows you to directly expose the contents of a Google spreadsheet as a service.

      • Query mode: Allows you to query a Google spreadsheet in a familiar, SQL-like manner, and expose the result as a service. You need to provide the name of the spreadsheet, in addition to the spreadsheet URL as shown below:
        

      See the next section on defining queries for more information on how the query mode affects how you query data in the spreadsheet.

3. Save the datasource.

4. Click Next to go to the Queries screen

You can define queries in two ways for a google spreadsheet, depending on whether or not Query mode is enabled for the datasource.

If query mode is disabled for the spreadsheet, you cannot use SQL statements to query data in the spreadsheet. Note that in non-query mode, you can only get data from the spreadsheet and you cannot insert, update or modify any data. 

1. Click Add New Query to open the Add New Query screen.

2. Enter Q1 as the query id in the Query ID field.

3. In the Datasource field, select the datasource for which you are going to write a query. Select the datasource for the Google spreadsheet that you created previously.

4. You can directly specify the details of the spreadsheet as shown below.
   

5. Define Output Mapping: Now, let's specify how the data fetched from the datasource should be displayed in the output. The google spreadsheet we are using contains several columns with customer data. We will create output mappings for the following columns: ID, CustomerNumber, CustomerName and City.

   1. In the Output type field, specify the format in which the query results should be presented. You can select XML, JSON or RDF. We will use XML for this tutorial.

   2. In the Grouped by element field, specify a grouping for all the output mappings. This will be the XML element that will group the query result. Enter Customers in this field. 

   3. In the Row Name field, specify the XML element that should group each individual result.  Enter Customer in this field.

   4. Click Add New Output Mapping to start creating the output mapping for the ID column. Enter values as shown below:
      

   5. Click Add to save the output mapping. You will now have one output mapping listed for the query.

   6. Now, add output mappings for the following:

      You will now have the following output mappings listed for the query:

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6. Click Next to go to the Operations screen.

You can query data in the spreadsheet using SQL statements.  At the moment, the query mode supports only the basic SELECT, INSERT, UPDATE and DELETE queries. Note that the Google spreadsheet sql driver does not accept the SELECT * command. Therefore, all the required select options (e.g., column names) should be specified in the query. See the following example: <sql>SELECT employeeId,name,salary FROM Sheet1 WHERE employeeId = ?</sql>. Nested queries will be supported in an upcoming release. 

1. Click Add New Query to open the Add New Query screen.

2. Enter Q1 as the query id in the Query ID field.

3. In the Datasource field, select the datasource for which you are going to write a query. Select the datasource for the Google spreadsheet that you created previously.

4. Specify an SQL query to insert data into the spreadsheet.

   INSERT INTO customers (customerNumber, customerName, city) VALUES(?,?,?)

5. Define Input Mapping: You need to create input mappings for the customerNumber, customerName and city columns specified in the above SQL statement. These input mapping parameters will be used for inserting data into the relevant columns. Click Generate Input Mapping, and default input mappings will be generated for all the fields that you have specified in your SQL statement as shown below.

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6. Click Next to go to the Operations screen.

Follow the steps given below.

1. Click Add New Operation to open the Add New Operation screen.

2. In the Operation Name field, enter a name for the operation.

3. In the Query ID field, select the query that you created.

4. Save the operation.