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

Here’s a scenario:

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

Let’s do it!

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title	Import Use +From URL to import a custom version of the file reader from git@bitbucket.org:interfaceware/file_tutorial.gitcomponent for this tutorial

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

You can useCreate component +FROM URL to import the component.

Copy paste the URL from here:

Code Block
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.

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

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

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title	Examine the Custom Field configurations in the component in config.json

To simplify the tutorial we have set these up a ClientList with the filename prefix Ids. Click on the config.json and you should see:

Image Added

See Custom Fields to understand how this was created.

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title	Click on MatchRules.lua in the Project Tree 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:

Code Block

language	lua

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.

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title	Let's extract the filename using FILfilename() from the FIL Library, 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.

Code Block

language	lua

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

These are the concepts we have used:

A function
FIL Library used to get the file name
Using trace() function

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title	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:

Image Removed

See Custom Fields to understand how this was created.

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title	Extract Edit MatchRules.lua to extract the prefixes from the custom fields

Now we need Create a second function, APPidList() to extract the fields ClientList prefixes from the custom configuration. So fields and update MatchFile() to call APPidList().

You can replace the contents of the MatchRules.lua file with this new contentcode:

Code Block

language	lua

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:

/wiki/spaces/IXB/pages/3181903910
Writing a function
Using trace() function
Using APP as a prefix, see Using prefixes for naming code
Custom Fields

So we add one line

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title	Break the comma delimited string into a list

to get each prefix Id

We can quickly do this by adding one line to AppidList( ) after line 2:

Code Block

language	lua

IdList = IdList:split(",")

You should see something like:

Concepts used:

String:split()

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

So now we make Create a third function, APPmatchPrefix() to determine if the file name matches filename matches the prefix. You can copy the code below:

Code Block

language	lua

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. You will need to type in the line as part of Match file to call APPmatchPrefix:See the screenshot below and add a line to MatchFile() to call and invoke the AppmatchPrefix() function.

Concepts used:

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

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

Code Block

language	lua

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:

...

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