# Having trouble implementating a Tables.jl row-table; when using BadukGoWeiqiTools, DataFrame(tbl) no longer works!

**URL:** <https://discourse.julialang.org/t/having-trouble-implementating-a-tables-jl-row-table-when-using-badukgoweiqitools-dataframe-tbl-no-longer-works/63622>\
**Category:** New to Julia\
**Created:** [June 27, 2021, 1:24am UTC](https://discourse.julialang.org/t/having-trouble-implementating-a-tables-jl-row-table-when-using-badukgoweiqitools-dataframe-tbl-no-longer-works/63622 "2021-06-27T01:24:47Z")\
**Posts on this page:** 1\
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**Author:** ![Sukera](https://avatars.discourse-cdn.com/v4/letter/s/ce7236/32.png) [@Sukera](https://discourse.julialang.org/u/Sukera)\
**Post date:** [June 27, 2021, 5:51am UTC](https://discourse.julialang.org/t/having-trouble-implementating-a-tables-jl-row-table-when-using-badukgoweiqitools-dataframe-tbl-no-longer-works/63622/3 "2021-06-27T05:51:44Z")

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The ambiguity is caused by ` promote_type(::Type{T}, ::Type{String})`. Since every type is a supertype of `Union` (as it’s the bottom type in the type lattice), neither method is more specific than the other. I’d investigate/open an issue about why `DataFrames` calls that promotion in the first place, it [shouldn’t do that](https://youtu.be/TPuJsgyu87U?t=781). `WeakRefStrings` seems to be behaving correctly here, since their `T` is restricted to being subtypes of their own type.

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