`schema()` 's show (print) method raises error

[cgiachalis]

The print method of tiledb_array_schema object raises an error when passing a tiledb_array object on write mode.

reprex:

library(tiledb)

uri <- tempfile()
df <- data.frame(id = 1:2, val= c(10, 20))
fromDataFrame(df, uri, col_index  = 1)

arr <- tiledb_array(uri, query_type = "WRITE", keep_open = TRUE)

# verify is opened in write mode
tiledb_array_is_open_for_writing(arr)
#> [1] TRUE

# so far OK
sch <- schema(arr)
attr <- attrs(sch) # just a check


# but printing...
schema(arr)
#> Error:
#> ! [TileDB::Array] Error: Cannot open array; Array already open.


# Now reopen to READ mode
arr <- tiledb_array_close(arr)

arr <- tiledb_array_open(arr, type = "READ")

# Good
schema(arr)
#> tiledb_array_schema(
#>     domain=tiledb_domain(c(
#>         tiledb_dim(name="id", domain=c(1L,2L), tile=2L, type="INT32", filter_list=tiledb_filter_list(c(tiledb_filter_set_option(tiledb_filter("ZSTD"),"COMPRESSION_LEVEL",-1))))
#>     )),
#>     attrs=c(
#>         tiledb_attr(name="val", type="FLOAT64", ncells=1, nullable=FALSE, filter_list=tiledb_filter_list(c(tiledb_filter_set_option(tiledb_filter("ZSTD"),"COMPRESSION_LEVEL",-1))))
#>     ),
#>     cell_order="COL_MAJOR", tile_order="COL_MAJOR", capacity=10000, sparse=TRUE, allows_dups=TRUE,
#>     coords_filter_list=tiledb_filter_list(c(tiledb_filter_set_option(tiledb_filter("ZSTD"),"COMPRESSION_LEVEL",-1))),
#>     offsets_filter_list=tiledb_filter_list(c(tiledb_filter_set_option(tiledb_filter("ZSTD"),"COMPRESSION_LEVEL",-1))),
#>     validity_filter_list=tiledb_filter_list(c(tiledb_filter_set_option(tiledb_filter("RLE"),"COMPRESSION_LEVEL",-1)))
#> )

Root cause

The issue is in the internal text helper .as_text_attribute that checks if the array pointer is open in READ mode and not just opened:

TileDB-R/R/Attribute.R

Line 110 in 3760c68

if (!libtiledb_array_is_open_for_reading(arrptr)) arrptr <- libtiledb_array_open_with_ptr(arrptr, "READ")

A bit of background on schema show method: if you pass a tiledb_array object, it uses the array pointer to query about enums and construct the schema for printing. In case you pass a uri, the print function will not show any enums (incomplete schema).

Also, .as_text_attribute will print "dictionary"/"ordered_dictionary" which is not the case as the correct argument in tiledb_attr is enumerations. Run the example in #854 and print the schema using the array..

TileDB-R/R/Attribute.R

Line 117 in 3760c68

dictionary_txt <- if (ord) "ordered_dictionary" else "dictionary"