# Data Validation Rules

#### Duncan Garmonsway

#### 2018-03-26

## What data validation rules are

Data validation rules control what constants can be entered into a cell, e.g. any whole number between 0 and 9, or one of several values from another part of the spreadsheet.

‘xlsx_validation()’ returns each of the data validation rules in an xlsx file, and the ranges of cells to which each rule applies.

Here is a rule that restricts input to integers between 0 and 9 inclusive, or no value (blank). If any other value is attempted, then an error message is displayed with the imaginative title “message title”, the informative body text “message body”, and a “stop” symbol.

    library(tidyxl)
    library(dplyr)
    #>
    #> Attaching package: 'dplyr'
    #> The following objects are masked from 'package:stats':
    #>
    #>     filter, lag
    #> The following objects are masked from 'package:base':
    #>
    #>     intersect, setdiff, setequal, union
    library(tidyr)
    examples <- system.file("extdata/examples.xlsx", package = "tidyxl")
    glimpse(xlsx_validation(examples)[1, ])
    #> Observations: 1
    #> Variables: 14
    #> $ sheet              <chr> "Sheet1"
    #> $ ref                <chr> "A106"
    #> $ type               <chr> "whole"
    #> $ operator           <chr> "between"
    #> $ formula1           <chr> "0"
    #> $ formula2           <chr> "9"
    #> $ allow_blank        <lgl> TRUE
    #> $ show_input_message <lgl> TRUE
    #> $ prompt_title       <chr> "message title"
    #> $ prompt_body        <chr> "message body"
    #> $ show_error_message <lgl> TRUE
    #> $ error_title        <chr> "error title"
    #> $ error_body         <chr> "error body"
    #> $ error_symbol       <chr> "stop"

The gamut of possible rules is given in the examples for `xlsx_validation()`.

    as.data.frame(xlsx_validation(examples))
    #>     sheet            ref       type           operator            formula1
    #> 1  Sheet1           A106      whole            between                   0
    #> 2  Sheet1           A108       list               <NA>              $B$108
    #> 3  Sheet1           A110       date            between 2017-01-01 00:00:00
    #> 4  Sheet1           A111       time            between            00:00:00
    #> 5  Sheet1           A112 textLength            between                   0
    #> 6  Sheet1           A114      whole         notBetween                   0
    #> 7  Sheet1 A115,A121:A122      whole              equal                   0
    #> 8  Sheet1           A116      whole           notEqual                   0
    #> 9  Sheet1           A117      whole        greaterThan                   0
    #> 10 Sheet1           A119      whole greaterThanOrEqual                   0
    #> 11 Sheet1           A120      whole    lessThanOrEqual                   0
    #> 12 Sheet1           A118      whole           lessThan                   0
    #> 13 Sheet1           A107    decimal         notBetween                   0
    #> 14 Sheet1           A113     custom               <NA>     A113<=LEN(B113)
    #> 15 Sheet1           A109       list               <NA>              $B$108
    #>               formula2 allow_blank show_input_message  prompt_title
    #> 1                    9        TRUE               TRUE message title
    #> 2                 <NA>        TRUE               TRUE          <NA>
    #> 3  2017-01-09 09:00:00        TRUE               TRUE          <NA>
    #> 4             09:00:00        TRUE               TRUE          <NA>
    #> 5                    9        TRUE               TRUE          <NA>
    #> 6                    9        TRUE               TRUE          <NA>
    #> 7                 <NA>        TRUE               TRUE          <NA>
    #> 8                 <NA>        TRUE               TRUE          <NA>
    #> 9                 <NA>        TRUE               TRUE          <NA>
    #> 10                <NA>        TRUE               TRUE          <NA>
    #> 11                <NA>        TRUE               TRUE          <NA>
    #> 12                <NA>        TRUE               TRUE          <NA>
    #> 13                   9       FALSE              FALSE          <NA>
    #> 14                <NA>        TRUE               TRUE          <NA>
    #> 15                <NA>        TRUE               TRUE          <NA>
    #>     prompt_body show_error_message error_title error_body error_symbol
    #> 1  message body               TRUE error title error body         stop
    #> 2          <NA>               TRUE        <NA>       <NA>      warning
    #> 3          <NA>               TRUE        <NA>       <NA>         stop
    #> 4          <NA>               TRUE        <NA>       <NA>         stop
    #> 5          <NA>               TRUE        <NA>       <NA>         stop
    #> 6          <NA>               TRUE        <NA>       <NA>         stop
    #> 7          <NA>               TRUE        <NA>       <NA>         stop
    #> 8          <NA>               TRUE        <NA>       <NA>         stop
    #> 9          <NA>               TRUE        <NA>       <NA>         stop
    #> 10         <NA>               TRUE        <NA>       <NA>         stop
    #> 11         <NA>               TRUE        <NA>       <NA>         stop
    #> 12         <NA>               TRUE        <NA>       <NA>         stop
    #> 13         <NA>              FALSE        <NA>       <NA>         stop
    #> 14         <NA>               TRUE        <NA>       <NA>         stop
    #> 15         <NA>               TRUE        <NA>       <NA>  information

## Joining rules to cells

> There are no built-in functions for joining ranges like `A1:D5,G8` to single cells like `B3`. For now, use the snippets in this section. In future I might develop a dplyr-like join function (this is hard currently because dplyr doesn’t yet join on arbitrary functions, or even the standard inequalities like `>=`). Help and advice would be gratefully accepted!

To join rules to cells, a naive method is to use the `sheet` and `ref` columns to match the `sheet` and `address` columns to the output of `xlsx_cells()`.

    rules <- xlsx_validation(examples)
    cells <- filter(xlsx_cells(examples), row >= 106, col == 1)

    rules
    #> # A tibble: 15 x 14
    #>    sheet  ref      type    operator    formula1    formula2    allow_blank
    #>    <chr>  <chr>    <chr>   <chr>       <chr>       <chr>       <lgl>
    #>  1 Sheet1 A106     whole   between     0           9           TRUE
    #>  2 Sheet1 A108     list    <NA>        $B$108      <NA>        TRUE
    #>  3 Sheet1 A110     date    between     2017-01-01… 2017-01-09… TRUE
    #>  4 Sheet1 A111     time    between     00:00:00    09:00:00    TRUE
    #>  5 Sheet1 A112     textLe… between     0           9           TRUE
    #>  6 Sheet1 A114     whole   notBetween  0           9           TRUE
    #>  7 Sheet1 A115,A1… whole   equal       0           <NA>        TRUE
    #>  8 Sheet1 A116     whole   notEqual    0           <NA>        TRUE
    #>  9 Sheet1 A117     whole   greaterThan 0           <NA>        TRUE
    #> 10 Sheet1 A119     whole   greaterTha… 0           <NA>        TRUE
    #> 11 Sheet1 A120     whole   lessThanOr… 0           <NA>        TRUE
    #> 12 Sheet1 A118     whole   lessThan    0           <NA>        TRUE
    #> 13 Sheet1 A107     decimal notBetween  0           9           FALSE
    #> 14 Sheet1 A113     custom  <NA>        A113<=LEN(… <NA>        TRUE
    #> 15 Sheet1 A109     list    <NA>        $B$108      <NA>        TRUE
    #> # ... with 7 more variables: show_input_message <lgl>, prompt_title <chr>,
    #> #   prompt_body <chr>, show_error_message <lgl>, error_title <chr>,
    #> #   error_body <chr>, error_symbol <chr>
    cells
    #> # A tibble: 93 x 21
    #>    sheet  address   row   col is_blank data_type error logical numeric
    #>    <chr>  <chr>   <int> <int> <lgl>    <chr>     <chr> <lgl>     <dbl>
    #>  1 Sheet1 A106      106     1 FALSE    numeric   <NA>  NA        0.
    #>  2 Sheet1 A107      107     1 FALSE    numeric   <NA>  NA        0.100
    #>  3 Sheet1 A108      108     1 FALSE    character <NA>  NA       NA
    #>  4 Sheet1 A109      109     1 FALSE    character <NA>  NA       NA
    #>  5 Sheet1 A110      110     1 FALSE    date      <NA>  NA       NA
    #>  6 Sheet1 A111      111     1 FALSE    date      <NA>  NA       NA
    #>  7 Sheet1 A112      112     1 FALSE    character <NA>  NA       NA
    #>  8 Sheet1 A113      113     1 FALSE    numeric   <NA>  NA       10.0
    #>  9 Sheet1 A114      114     1 FALSE    numeric   <NA>  NA       -1.00
    #> 10 Sheet1 A115      115     1 FALSE    numeric   <NA>  NA        0.
    #> # ... with 83 more rows, and 12 more variables: date <dttm>,
    #> #   character <chr>, character_formatted <list>, formula <chr>,
    #> #   is_array <lgl>, formula_ref <chr>, formula_group <int>, comment <chr>,
    #> #   height <dbl>, width <dbl>, style_format <chr>, local_format_id <int>

    inner_join(rules, cells, by = c("sheet" = "sheet", "ref" = "address"))
    #> # A tibble: 9 x 33
    #>   sheet  ref   type     operator   formula1      formula2      allow_blank
    #>   <chr>  <chr> <chr>    <chr>      <chr>         <chr>         <lgl>
    #> 1 Sheet1 A106  whole    between    0             9             TRUE
    #> 2 Sheet1 A108  list     <NA>       $B$108        <NA>          TRUE
    #> 3 Sheet1 A110  date     between    2017-01-01 0… 2017-01-09 0… TRUE
    #> 4 Sheet1 A111  time     between    00:00:00      09:00:00      TRUE
    #> 5 Sheet1 A112  textLen… between    0             9             TRUE
    #> 6 Sheet1 A114  whole    notBetween 0             9             TRUE
    #> 7 Sheet1 A107  decimal  notBetween 0             9             FALSE
    #> 8 Sheet1 A113  custom   <NA>       A113<=LEN(B1… <NA>          TRUE
    #> 9 Sheet1 A109  list     <NA>       $B$108        <NA>          TRUE
    #> # ... with 26 more variables: show_input_message <lgl>,
    #> #   prompt_title <chr>, prompt_body <chr>, show_error_message <lgl>,
    #> #   error_title <chr>, error_body <chr>, error_symbol <chr>, row <int>,
    #> #   col <int>, is_blank <lgl>, data_type <chr>, error <chr>,
    #> #   logical <lgl>, numeric <dbl>, date <dttm>, character <chr>,
    #> #   character_formatted <list>, formula <chr>, is_array <lgl>,
    #> #   formula_ref <chr>, formula_group <int>, comment <chr>, height <dbl>,
    #> #   width <dbl>, style_format <chr>, local_format_id <int>

Notice that only 9 cells were joined, even though 15 rules were defined. Surely at least 15 cells ought to be joined? The reason why they are not is that the cells for the other 6 rules don’t exist – rules can be defined for cells that have no value, and cells with no value are not returned by `xlsx_cells()`, otherwise all 17179869184 cells in a worksheet must be returned.

A more subtle reason for certain cells not to have joined successfully is that the `ref` column of the rules sometimes refers to more than one cell, and can even refer to several, non-contiguous ranges of cells. Specifically, the seventh rule’s `ref` column has `A115,A121:A122`.

Special treatment is needed here. Ideally, some kind of join function would be defined that can compare indidual cells with ranges. But I haven’t written one, so what follows is a workaround. First, the two ranges of cells must be `unnested` into `A115` and `A121:122`. Then the range `A121:122` must be ‘unranged’ into `A121` and `A122`.

    unrange <- function(x) {
      limits <- cellranger::as.cell_limits(x)
      rows <- seq(limits$ul[1], limits$lr[1])
      cols <- seq(limits$ul[2], limits$lr[2])
      rowcol <- expand.grid(rows, cols)
      cell_addrs <- cellranger::cell_addr(rowcol[[1]], rowcol[[2]])
      cellranger::to_string(cell_addrs, fo = "A1", strict = FALSE)
    }

    unnest_ref <- function(x, ref) {
      UseMethod("unnest_ref")
    }

    unnest_ref.default <- function(x, ref_col = ref) {
      stopifnot(is.character(x), length(x) == 1L)
      refs <- unlist(strsplit(x, ",", fixed = TRUE))
      unlist(lapply(refs, unrange))
    }

    unrange("A121:A122")
    #> [1] "A121" "A122"
    unnest_ref("A115,A121:A122")
    #> [1] "A115" "A121" "A122"

The `unnest_ref()` function can also be defined for whole data frames, unnesting them by a column of references.

    unnest_ref.data.frame <- function(x, ref_col) {
      ref <- rlang::enquo(ref_col)
      x[[rlang::quo_name(ref)]] <- lapply(x[[rlang::quo_name(ref)]], unnest_ref)
      tidyr::unnest(x, rlang::UQ(ref))
    }

    (nested_rule <- slice(rules, 7))
    #> # A tibble: 1 x 14
    #>   sheet  ref            type  operator formula1 formula2 allow_blank
    #>   <chr>  <chr>          <chr> <chr>    <chr>    <chr>    <lgl>
    #> 1 Sheet1 A115,A121:A122 whole equal    0        <NA>     TRUE
    #> # ... with 7 more variables: show_input_message <lgl>, prompt_title <chr>,
    #> #   prompt_body <chr>, show_error_message <lgl>, error_title <chr>,
    #> #   error_body <chr>, error_symbol <chr>
    unnest_ref(nested_rule, ref)
    #> # A tibble: 3 x 14
    #>   sheet  type  operator formula1 formula2 allow_blank show_input_message
    #>   <chr>  <chr> <chr>    <chr>    <chr>    <lgl>       <lgl>
    #> 1 Sheet1 whole equal    0        <NA>     TRUE        TRUE
    #> 2 Sheet1 whole equal    0        <NA>     TRUE        TRUE
    #> 3 Sheet1 whole equal    0        <NA>     TRUE        TRUE
    #> # ... with 7 more variables: prompt_title <chr>, prompt_body <chr>,
    #> #   show_error_message <lgl>, error_title <chr>, error_body <chr>,
    #> #   error_symbol <chr>, ref <chr>

Finally the new data frame of rules can be joined to a data frame of cells in any of the usual ways, via the `sheet` and `ref` columns.

Problems with this approach occur with rules that are defined over large ranges of cells: the ‘unnesting’ of those ranges results in very long vectors of individual cell addresses, or (worse) huge data frames of rules. Such cases are commonplace, because rules are often defined for entire columns of a spreadsheet, and a column has 1048576 rows.