bugfix: Table Data Parser can have undefined inputs

[ymiftah]

Background

When defining my system through CSV, without any dc_branch.csv, the TableData parser failed to create the system.

Bug description

The CSV files are parsed iteratively, with the get_dataframe function reading the TableData as a dataframe
the get_dataframe function defaults to an empty dataframe if the InputCategory is not defined, not a nothing. The check should be aligned

Happy to provide more context in an issue linked to this

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.52%. Comparing base (4eb1bea) to head (e5cf0c9).
Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1186      +/-   ##
==========================================
- Coverage   84.55%   84.52%   -0.03%     
==========================================
  Files         181      181              
  Lines        8389     8389              
==========================================
- Hits         7093     7091       -2     
- Misses       1296     1298       +2     

Flag	Coverage Δ
unittests	84.52% <100.00%> (-0.03%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/parsers/power_system_table_data.jl	82.06% <100.00%> (-0.30%)	⬇️

[pesap]

@ymiftah , if you add an empty dc_branch.csv to the folder where you are parsing the CSV data, does it work?

[ymiftah]

With an empty dc_branch.csv file, the system is parsed with a warning (as expected)

julia> data
PowerSystems.PowerSystemTableData:
  directory:  ../notebooks/siiptest
  base_power:  100.0
  PowerSystems.InputCategoryModule.InputCategory.GENERATOR = 4:  0×0 DataFrame
  PowerSystems.InputCategoryModule.InputCategory.BUS = 2:  6×17 DataFrame
  PowerSystems.InputCategoryModule.InputCategory.DC_BRANCH = 3:  0×0 DataFrame
  PowerSystems.InputCategoryModule.InputCategory.LOAD = 5:  0×0 DataFrame
  PowerSystems.InputCategoryModule.InputCategory.BRANCH = 1:  16×13 DataFrame

Truncated output

sys = PSY.System(data)
...
┌ Warning: Missing PowerSystems.InputCategoryModule.InputCategory.DC_BRANCH = 3 data.
└ @ PowerSystems ~/.julia/dev/PowerSystems/src/parsers/power_system_table_data.jl:212

System
┌───────────────────┬─────────────┐
│ Property          │ Value       │
├───────────────────┼─────────────┤
│ Name              │             │
│ Description       │             │
│ System Units Base │ DEVICE_BASE │
│ Base Power        │ 100.0       │
│ Base Frequency    │ 60.0        │
│ Num Components    │ 46          │
└───────────────────┴─────────────┘

Static Components
┌──────────┬───────┐
│ Type     │ Count │
├──────────┼───────┤
│ ACBus    │ 6     │
│ Arc      │ 12    │
│ Area     │ 6     │
│ Line     │ 16    │
│ LoadZone │ 6     │
└──────────┴───────┘

PS: I do not have a fully/correctly defined set of csv yet (working around this issue #1185) , so i actually ran this with empty generators and loads csv files as well.

PPS: It would still throw an error without this bugfix