app re-downloads data package from same DOI

[atn38]

Describe the problem:

The app re-downloads and re-ingests the data package from one DOI if

• the user exits out and reopens the GUI, putting in the same DOI each time (same R session, different GUI session).
• the user, after looking at one data package (DOI 1), downloads another (DOI 2), and then inputs DOI 1 again (same R session, same GUI session).

Proposed solution: app should look for and load already download data packages in tempdir(). tempdir() gets re-set with every new R session; within the same R session, users should not have to re-download data packages.

Expanded solution for future: Users might want to look at multiple packages in one GUI session. After the first download, populate a GUI drop-down menu with the already downloaded packages. Should users want to re-visit a DOI, they select from the menu, not paste in the DOI again.

---

R version 3.6.0 (2019-04-26)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 17763)

Matrix products: default

locale:
[1] LC_COLLATE=English_United States.1252  LC_CTYPE=English_United States.1252   
[3] LC_MONETARY=English_United States.1252 LC_NUMERIC=C                          
[5] LC_TIME=English_United States.1252    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] scales_1.0.0       cowplot_0.9.4      lubridate_1.7.4    ggplot2_3.1.1      shiny_1.3.2        datapie_0.0.0.9000
[7] testthat_2.1.1    

loaded via a namespace (and not attached):
  [1] nlme_3.1-140       fs_1.3.1           usethis_1.5.0      devtools_2.0.2     RColorBrewer_1.1-2
  [6] httr_1.4.0         rprojroot_1.3-2    tools_3.6.0        backports_1.1.4    R6_2.4.0          
 [11] lazyeval_0.2.2     colorspace_1.4-1   withr_2.1.2        tidyselect_0.2.5   prettyunits_1.0.2 
 [16] processx_3.3.1     curl_3.3           compiler_3.6.0     rvest_0.3.4        datapack_1.3.1    
 [21] cli_1.1.0          jsonld_2.1         xml2_1.2.0         shinyjs_1.0        desc_1.2.0        
 [26] plotly_4.9.0       labeling_0.3       readr_1.3.1        askpass_1.1        callr_3.2.0       
 [31] commonmark_1.7     stringr_1.4.0      digest_0.6.19      rmarkdown_1.12     base64enc_0.1-3   
 [36] pkgconfig_2.0.2    htmltools_0.3.6    sessioninfo_1.1.1  highr_0.8          htmlwidgets_1.3   
 [41] rlang_0.3.4        readxl_1.3.1       rstudioapi_0.10    generics_0.0.2     emld_0.2.0        
 [46] jsonlite_1.6       dplyr_0.8.1        magrittr_1.5       Rcpp_1.0.1         munsell_0.5.0     
 [51] stringi_1.4.3      yaml_2.2.0         jqr_1.1.0          pkgbuild_1.0.3     plyr_1.8.4        
 [56] grid_3.6.0         shinyFiles_0.7.3   EML_2.0.0          promises_1.0.1     forcats_0.4.0     
 [61] crayon_1.3.4       lattice_0.20-38    haven_2.1.0        redland_1.0.17-10  hash_2.2.6.1      
 [66] hms_0.4.2          knitr_1.22         parsedate_1.2.0    ps_1.3.0           pillar_1.4.0      
 [71] uuid_0.1-2         dataone_2.1.2      pkgload_1.0.2      XML_3.98-1.19      glue_1.3.1        
 [76] packrat_0.5.0      evaluate_0.13      V8_2.2             modelr_0.1.4       data.table_1.12.2 
 [81] remotes_2.0.4      httpuv_1.5.1       cellranger_1.1.0   openssl_1.3        gtable_0.3.0      
 [86] purrr_0.3.2        tidyr_0.8.3        assertthat_0.2.1   xfun_0.7           mime_0.6          
 [91] broom_0.5.2        xtable_1.8-4       tidyverse_1.2.1    roxygen2_6.1.1     later_0.8.0       
 [96] rsconnect_0.8.13   viridisLite_0.3.0  tibble_2.1.1       memoise_1.1.0      metajam_0.2.0.9000