closes #784 by fixing typename + tests

[tlienart]

• fixes typename for DataFrames.DataFrame object, tested with 1.0 to 1.7 seems ok
• added simple tests for it (required adding DataFrames to the extras)

Note: this isdataframe stuff should eventually be removed via improvements to Tables.jl (see here) but for now is necessary to avoid big bottlenecks.

[tlienart]

thanks for the review @OkonSamuel feel free to take this over, I'm not close enough to the Tables API to know what's best so I trust your choices are better, it might be good to check the tests are right, maybe do a side test with what brought Jack_N to open the issue in the first place and check that there's no bottleneck anymore?

[jackn11]

Thank you both for helping with the changes. Also, it may be a good idea to make the slight modification to the selectcols function so that the '!' is not needed in the if statement. The code is below so you can see what I mean. Removing the unnecessary double negative should help keep the code clean and understandable.

function MMI.selectcols(::FI, ::Val{:table}, X, c::Union{Symbol, Integer})
    if isdataframe(X)
        return X[!, c]
    else
        cols = Tables.columntable(X) # named tuple of vectors
        return cols[c]
    end
end

function MMI.selectcols(::FI, ::Val{:table}, X, c::AbstractArray)
    if isdataframe(X)
        return X[!, c]
    else
        cols = Tables.columntable(X) # named tuple of vectors
        newcols = project(cols, c)
        return Tables.materializer(X)(newcols)
    end
end

[codecov-commenter]

Codecov Report

Merging #786 (ca69c2f) into dev (2257471) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##              dev     #786   +/-   ##
=======================================
  Coverage   85.92%   85.93%           
=======================================
  Files          36       36           
  Lines        3460     3462    +2     
=======================================
+ Hits         2973     2975    +2     
  Misses        487      487           

Impacted Files	Coverage Δ
src/interface/data_utils.jl	96.87% <100.00%> (+0.10%)	⬆️

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[ablaom]

@OkonSamuel I'm happy with this, modulo my single suggestion. Please merge and tag a new release at your leisure.

[tlienart]

I just merged (it was my branch so not sure if sam could do it) will leave the tag & release to you guys

[ablaom]

Thank you @tlienart and @OkonSamuel . A new release just tagged.