Parsing an object from multiple source files

Question

I receive zip files and they have as content 8 different files, each with it's own metadata inside.

I have to combine these files into 1 object containing certain metadata. The big issue here is that there will not always be 8 files and the metadata i want to retrieve could be in any of these files stored in there own way.

for now i have created a factory method that initiates the correct parser for each file type and the parser returns the object with the metadata it was able to parse.

Now when this is done i have 8 object's i have to merge into 1 result object with the metadata gathered from these results.

so i could have something like this

object Meta1 Meta2 Meta3 Meta4 Meta5
1 A - 15 RT -
2 - - 15 - HIGH
3 A - 15 RT HIGH
4 - 65 - RT HIGH

This needs to have only 1 object as output:

Meta1 Meta2 Meta3 Meta4 Meta5
A 65 15 RT HIGH

Now i'm wondering what would be the best strategy to solve this issue

• Have my parsers accept my Object as parameter, try to map the data and override if present and then return the Object to be passed again in the next Parser
• Parse all the Object and try to merge them somehow in the end
• Another strategy?

• Brian: Is the handler known before the data is loaded? Given file1 and file2, will your code use load(file1);load(file2) or load1(file1);load2(file2);?
• JMan: I receive the files loaded and have allready determined the required handler to parse them

Answer 1

Here I describe some similar work I did. Perhaps it will work for you. I had 7 different file formats across 2 different files.

What I must assume is that your meta-data is effectively keys. Otherwise how can one possibly know which records to merge?

• Create a CommonData class

  • A single class to hold any record from any file.
  • A property for each possible meta-field from any incoming file
  • A property to hold the entire record
  • As you clearly illustrate - Where meta-fields are the same, there is only one. I.E. only 1 "Meta1", "Meta2"
  • Populate only the appropriate meta fields for a given file/record format.
  • An enum identifing the record type - what file it comes from essentially; or for me, the file format.
  • Has an IEqualityComparer

• CommonDataEqualityComparer

  • Implements IEqualityComparer
  • In my solution your "meta data" were my keys that defined equality for each given record type (file).
  • The equality-comparer object is passed into the CommonData constructor.

• An enum to identify each source file or unique file format.

• The Factory

  • takes the raw record and it's type - enum value
  • Factory passes to appropriate parser based on the enum value
  • Factory returns new CommonData object, with it's record-type-specific CommonDataEqualityComparer implementation.

• CommonDataCollection

  • Between the equality-comparer implementations and RecordType property we can find, match, etc. records for each file type.