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Explore Your Generated OData Service
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Explore Your Generated OData Service

09/25/2018

Explore the product data in your OData service you've just generated.

You will learn

  • How to use the SQL Console
  • How to import data from a CSV source
  • How your generated OData service supports standard OData query operation parameters

This tutorial assumes you’ve completed the tutorial Add Data to your OData Service. At this stage you have your generated OData service and you’ve populated it with some sample product data, either data of your own, or from the Northwind data set. It’s now time to explore your OData service to see that it functions, out of the box, just like any other.

In this tutorial and others the general name “SAP Web IDE” is used. Specifically, the “Full-Stack” version is implied throughout.


Step 1: Start up the SAP Web IDE

Access SAP Web IDE from your trial SAP Cloud Platform cockpit. Use the details in the tutorial Enable the SAP Web IDE Full Stack to find out how to access it, or simply invoke it using a URL which will look like this:

https://webidecp-XYZ.dispatcher.hanatrial.ondemand.com/

Here, XYZ represents your trial subaccount name, such as p999999trial.

You can find out more about accessing the SAP Web IDE in the Help Portal, specifically in the “Open SAP Web IDE” section.

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Step 2: Remove any existing data

It’s quite likely that you’ve only entered a few products in the preceding prerequisite tutorial. In this case, the query operations you’ll be carrying out won’t return very much data. To make it more interesting, you will import all of Northwind’s products in this step.

Before importing data, it’s best to remove any existing data that you’ve entered.

Do this by using the SQL Console in the Database Explorer perspective. Use the Open SQL Console button as indicated, then enter the following statement into the console and execute it.

delete from my_app_products;
SQL Console delete

On execution, you should see a message similar to the following:

Statement 'delete from my_app_products'
executed in 2 ms - Rows Affected: 3
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Step 3: Import fresh Northwind data

You can import the Northwind product data by providing a couple of files – a CSV file containing the data, and a file that defines the data source and how the fields map between the data source and the target table in the database.

Back in the Development perspective, within the db/src folder, create a new folder called csv. Import into this new folder the following two files:

Make sure you choose the src folder within the db folder, not the one within the srv folder.

When you’ve done this, you should see these files in the explorer, thus:

contents of CSV folder

Now you can rerun the database build facility that will recognize the new artifacts and import the data automatically. To do this, use the context menu on the db folder and choose menu path Build > Build.

If you check in the Console during or after this operation, you’ll see references to the Products.csv and Data.hdbtabledata files being recognized and processed accordingly.

You should now have quite a few products in your table, plenty to explore with OData queries!

How many products were imported in total?
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Step 4: Try out a few OData queries on your service

You’re all set. Your OData service should respond to you in a way that feels completely familiar. In this step, put it through its paces by constructing some query operations.

Before you do, make sure the OData service, in the form of the Java app in the srv folder, is still running. Open the Run Console with menu path View > Run Console. If the service is running, you’ll see the URL as before. If not, use the green Run button on the far right to restart it. What you’ll see should look something like this:

the OData service running

Like you did in previous prerequisite tutorials, follow the URL to find your OData service’s service document. The URL should look something like this:

https://3om1s7cblrlhamdk-products-srv.cfapps.eu10.hana.ondemand.com/odata/v2/CatalogService

The first part of the URL is generated and will look different in your case.

Service metadata

Append /$metadata to the end of the service document URL to look at the OData service’s metadata:

https://3om1s7cblrlhamdk-products-srv.cfapps.eu10.hana.ondemand.com/odata/v2/CatalogService/$metadata

You should see something like this, where you can see that the name of the entity set is Products:

metadata document

In this case the name of the entity set is the same name as the entity type.

Products

Ask for the Products entity set by replacing $metadata with Products in the URL:

https://3om1s7cblrlhamdk-products-srv.cfapps.eu10.hana.ondemand.com/odata/v2/CatalogService/Products

You should see an XML formatted list of products, like this:

XML entity set

Request the same resource but in a different representation – JavaScript Object Notation (JSON) – with the $format system query option:

https://3om1s7cblrlhamdk-products-srv.cfapps.eu10.hana.ondemand.com/odata/v2/CatalogService/Products?$format=json

Low stock products

Ask to see those products where the stock is very low, with the $filter system query option:

https://3om1s7cblrlhamdk-products-srv.cfapps.eu10.hana.ondemand.com/odata/v2/CatalogService/Products?$format=json&$filter=UnitsInStock lt 5

When you enter this in your browser, any spaces will be URL encoded into %20 values.

Rather than read through the resulting payload to find out how many there are, ask directly, with $count:

https://3om1s7cblrlhamdk-products-srv.cfapps.eu10.hana.ondemand.com/odata/v2/CatalogService/Products/$count?$filter=UnitsInStock lt 5

The $format system query option cannot be used with $count so it has been removed from this query.

Product with largest stock

Ask to see the product with the largest amount of units in stock:

https://3om1s7cblrlhamdk-products-srv.cfapps.eu10.hana.ondemand.com/odata/v2/CatalogService/Products?$orderby=UnitsInStock desc&$top=1

As you can see, the OData service, for which you haven’t had to write a single line of code, is performing as expected. Feel free to explore more standard OData features, perhaps those that you discovered in the Learn about OData Fundamentals tutorial. Good luck!

How many products are low on stock (where the units in stock is less than 5)?
×

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