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This is good example how we can Eliminate bottlenecks with IguanaX by building a custom file reader component which has a simple interface for a unique purpose rather using a general purpose no code solution - see The problem with no-code solutions

A large lab needs to have a file reading component which can feed files from different customers based on prefix of the file, i.e. some files start with JJ99, others XYZ etc. depending on the source.

Let’s do it!

 Import a custom version of the file reader from git@bitbucket.org:interfaceware/file_tutorial.git

Create component +FROM URL

Copy paste the URL from here:

git@bitbucket.org:interfaceware/file_tutorial.git

This component generates some test files to make it easier to learn how to make a custom file reader.

 Click on the Customize and Copy and Edit button so you can alter the source code

See Customizing components to see how done if you have not done this before.

 Click on MatchRules.lua to see where we need to alter the code

Navigate to MatchRules.lua in the Project Tree. This is the function we need to alter:

function MatchFile(FileName)
   return true
end

The file reader component is deliberately simple and uses /wiki/spaces/IXB/pages/3181903910 to make it more obvious how to modify the code to meet new needs. We need this function to return true when the matching criteria are met.

 Let's extract the filename so we can look at it:

Change the matching to add in two lines so we can see the filenames we need to filter on.

function MatchFile(FileName)
   local JustFileName = FILfilename(FileName)
   trace(JustFileName)
   return true
end

These are the concepts we have used:

 Examine the custom configuration in the component

To simplify the tutorial we have set these up already. Click on the config.json and you should see:

See Custom Fields to understand how this was created.

 Extract the prefixes from the custom fields

Now we need to extract the fields from the custom configuration. So replace the contents of the MatchRules.lua file with this new content:

function APPidList()
   local IdList = component.fields()["ClientList"]
   return IdList
end

function MatchFile(FileName)
   local IdList = APPidList()
   trace(IdList)
   local JustFileName = FILfilename(FileName)
   trace(JustFileName)
   return true
end

Concepts used:

 Break the comma delimited string into a list

So we add one line after line 2:

IdList = IdList:split(",")

You should see something like:

Concepts used:

 Make a function which takes the prefix and sees if the filename starts with it

So now we make a function to determine if the file name matches 

function APPmatchPrefix(Prefix, FileName)
   local Part = FileName:sub(1, #Prefix)
   trace(Part, Prefix)
   return (Part == Prefix)
end

And we’ll call it as part of the MatchFile routine:

Concepts used:

 Now change the matching code so we go through all the of the list

Let’s modify the code to go through the entire list of prefixes:

for i = 1, #IdList do
   if APPmatchPrefix(IdList[i], JustFileName) then 
      return true
   end
end
return false -- we didn't match anything

And this is what you should see:

Concepts used:

 Commit your changes, alter the component to run on the new commit and run it!

Commit and Push Changes to Git and go to the component card for Choosing the code to run for your component.

And done! The next steps are how you could further refine the code

 Make the configuration more robust by striping white space from the list ClientList

That would involve looping through the list and removing white space from each ID:

Concepts:

 Customize the logging

See Custom Logging

 Customize the status

See Custom Status

There is no limit to how you can streamline the usage of a custom component - if that helps address a bottleneck, then it is well worth it.  

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