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title	Import the JSON Filter Tutorial component using +FROM URL

UseCreate component +FROM URL to import the component.

Copy paste the following URL:

Code Block
git@bitbucket.org:interfaceware/json_tutorial.git

This component includes Sample Data to make it easier to learn how to filter messages.

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title	Click on the Customize then the Copy and Edit button so you can access the Translator and alter the code

Refer to Customizing components Edit a Component to see how it's done if you have not done this before.

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title	Use the Annotation Window to view your sample data in the String Viewing Window

Now we are in the Developing in the Translator!

Every Translator component contains a Main.lua module with a main function Functions that is called each time a message is received or on a configured poll time.

Notice we can see our sample data (variable Variables named Data) passed to main functionby looking at the Annotation Windows.

If we click on the sample data in the annotations, we can view it using The string viewing window.

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title	Parse the JSON sample data using json.parse{data=Data}

In main, parse the JSON sample data by passing Data. Create and assign the parsed data to a patient Variable variable.

Code Block

language	lua

local patient = json.parse{data=Data}

JSON objects are parsed into Lua tables as dictionaries with key-value pairs. You can see this by clicking the resulting table in the Annotation Window.

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title	Create a filter.lua module to start building a filter function

Use the Create a File button to create a new filters.lua file in your Project Tree. Click Create.

Notice that when you create a new lua file, Iguana will automatically add a Require Statement to main.lua.

See /wiki/spaces/IXB/pages/3181903910 for why we created a separate lua module specifically for filtering.

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title	Create a filter function in filters.lua

Notice we are brought to an empty filters.lua script in the project tree. Lets add our filtering logic:

First, create a filter function Block statements and pass patient as the parameter.

Code Block

language	lua

function filter(patient)
   
end

Then go into main and call your filter function, passing your parsed patient JSON as the expected parameter.

Notice after calling our filter function,

Navigate back to the filter.lua by clicking the purple filter in the Annotation Windows, notice there is now an annotation block we can use to add the rest of the logic.

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title	Use another if statement in main to test if a message should be queued or filtered out

Your main function should look like this:

This if statement is testing if the filter function returns true - the domain name equalled “interfaceware.com” - then queue the message to be processed by the next component.

See How Push Messages to push messages into a queue?a Component Queue.

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title	Now let's see our filtering in action by going through the sample data and viewing the annotations

By switching which Sample Data is being passed to main, we can see the results and test how our filter function works, by using the annotations.

Navigate to filters.lua and switch to the second sample data to see the sample message fail the condition and return false.

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title	Add custom logging to your filter to make it more comprehensive

Now that the annotations are active for the failed scenario, we can leverage them to add Custom Logging to add more visibility into the logs.

For example,

Code Block

language	lua

if domain == 'interfaceware.com' then
  return true
else 
  iguana.log('Filtered out message with: '..domain)   
  return false
end

You’re done the filter! Don’t forget to Commit and Push Changes to Git.

Now back to the Orientation!

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