jenny Fri May 13 09:40:57 2016
Task: create XML to update contents of cells in a Google Sheet.
Here's how I currently do it with the XML package.
library(readr)
library(XML)
#> Warning: package 'XML' was built under R version 3.2.4
library(purrr)
update_fodder <- read_csv("27_update-fodder.csv")
africa_cellsfeed <- "SOME_URL"
f_XML <- function(cell, cell_id, edit_link, row, col, update_value) {
XML::xmlNode("entry",
XML::xmlNode("batch:id", cell),
XML::xmlNode("batch:operation",
attrs = c("type" = "update")),
XML::xmlNode("id", cell_id),
XML::xmlNode("link",
attrs = c("rel" = "edit",
"type" = "application/atom+xml",
"href" = edit_link)),
XML::xmlNode("gs:cell",
attrs = c("row" = row,
"col" = col,
"inputValue" = update_value)))
}
list_of_nodes <- update_fodder %>%
pmap(f_XML)
feed_node <-
xmlNode("feed",
namespaceDefinitions =
c("http://www.w3.org/2005/Atom",
batch = "http://schemas.google.com/gdata/batch",
gs = "http://schemas.google.com/spreadsheets/2006"),
.children = list(xmlNode("id", africa_cellsfeed))) %>%
addChildren(kids = list_of_nodes)
## here's what I actually send as body of an httr::POST request:
write(toString.XMLNode(feed_node), "27_feed-node-XML.xml")Installing / verifying xml2 from the relevant PR.
#devtools::install_github("hadley/xml2#76")
si <- devtools::session_info("xml2")$packages
si$source[si$package == "xml2"]
#> [1] "Github (jimhester/xml2@63e5c1c)"Current approach given by @jimhester.
library(xml2)
d <- xml_new_document() %>%
xml_add_child("feed",
xmlns = "http://www.w3.org/2005/Atom",
"xmlns:batch" = "http://schemas.google.com/gdata/batch",
"xmlns:gs" = "http://schemas.google.com/spreadsheets/2006")
d %>% xml_add_child("id", africa_cellsfeed)
#> {xml_node}
#> <id>
f_XML <- function(cell, cell_id, edit_link, row, col, update_value) {
d %>%
xml_add_child("entry") %>%
xml_add_child("batch:id", cell) %>%
xml_add_sibling("batch:operation", type = "update") %>%
xml_add_sibling("id", cell_id) %>%
xml_add_sibling("link", rel = "edit", type = "application/atom+xml",
href = edit_link) %>%
xml_add_sibling("gs:cell", row = as.character(row), col = as.character(col),
inputValue = update_value)
}
update_fodder %>% pwalk(f_XML)
write_xml(d, "27_feed-node-xml2.xml")How does this compare to the output from the XML package? xml2 adds an XML declaration.
diff -b -U 0 27_feed-node-XML.xml 27_feed-node-xml2.xml
#> --- 27_feed-node-XML.xml 2016-05-13 09:40:58.000000000 -0700
#> +++ 27_feed-node-xml2.xml 2016-05-13 09:40:58.000000000 -0700
#> @@ -0,0 +1 @@
#> +<?xml version="1.0"?>Can xml2 roundtrip it's own XML? I.e. the new linebreaks don't cause trouble? I wonder because of r-lib/xml2#49.
rt <- read_xml("27_feed-node-xml2.xml")
identical(as_list(d), as_list(rt))
#> [1] FALSE
head(all.equal(as_list(d), as_list(rt)))
#> [1] "Names: 20 string mismatches"
#> [2] "Length mismatch: comparison on first 37 components"
#> [3] "Component 1: Modes: list, character"
#> [4] "Component 1: Component 1: 1 string mismatch"
#> [5] "Component 2: names for target but not for current"
#> [6] "Component 2: Length mismatch: comparison on first 1 components"
xml_children(d)[[2]]
#> {xml_node}
#> <entry>
#> [1] <batch:id>A1</batch:id>
#> [2] <batch:operation type="update"/>
#> [3] <id>https://spreadsheets.google.com/feeds/cells/1tP1SAErOJbMrTTCONdL ...
#> [4] <link rel="edit" type="application/atom+xml" href="https://spreadshe ...
#> [5] <gs:cell row="1" col="1" inputValue="country"/>
xml_children(rt)[[2]]
#> {xml_node}
#> <entry>
#> [1] <batch:id>A1</batch:id>
#> [2] <batch:operation type="update"/>
#> [3] <id>https://spreadsheets.google.com/feeds/cells/1tP1SAErOJbMrTTCONdL ...
#> [4] <link rel="edit" type="application/atom+xml" href="https://spreadshe ...
#> [5] <gs:cell row="1" col="1" inputValue="country"/>
as_list(xml_children(d)[[2]])
#> $id
#> $id[[1]]
#> [1] "A1"
#>
#>
#> $operation
#> list()
#> attr(,"type")
#> [1] "update"
#>
#> $id
#> $id[[1]]
#> [1] "https://spreadsheets.google.com/feeds/cells/1tP1SAErOJbMrTTCONdL0a9lwe3KkhTuZaGhCy3MPZP8/ozf3txt/private/full/R1C1"
#>
#>
#> $link
#> list()
#> attr(,"rel")
#> [1] "edit"
#> attr(,"type")
#> [1] "application/atom+xml"
#> attr(,"href")
#> [1] "https://spreadsheets.google.com/feeds/cells/1tP1SAErOJbMrTTCONdL0a9lwe3KkhTuZaGhCy3MPZP8/ozf3txt/private/full/R1C1/fu9n6e"
#>
#> $cell
#> list()
#> attr(,"row")
#> [1] "1"
#> attr(,"col")
#> [1] "1"
#> attr(,"inputValue")
#> [1] "country"
as_list(xml_children(rt)[[2]])
#> [[1]]
#> [1] "\n "
#>
#> $id
#> $id[[1]]
#> [1] "A1"
#>
#>
#> [[3]]
#> [1] "\n "
#>
#> $operation
#> list()
#> attr(,"type")
#> [1] "update"
#>
#> [[5]]
#> [1] "\n "
#>
#> $id
#> $id[[1]]
#> [1] "https://spreadsheets.google.com/feeds/cells/1tP1SAErOJbMrTTCONdL0a9lwe3KkhTuZaGhCy3MPZP8/ozf3txt/private/full/R1C1"
#>
#>
#> [[7]]
#> [1] "\n "
#>
#> $link
#> list()
#> attr(,"rel")
#> [1] "edit"
#> attr(,"type")
#> [1] "application/atom+xml"
#> attr(,"href")
#> [1] "https://spreadsheets.google.com/feeds/cells/1tP1SAErOJbMrTTCONdL0a9lwe3KkhTuZaGhCy3MPZP8/ozf3txt/private/full/R1C1/fu9n6e"
#>
#> [[9]]
#> [1] "\n "
#>
#> $cell
#> list()
#> attr(,"row")
#> [1] "1"
#> attr(,"col")
#> [1] "1"
#> attr(,"inputValue")
#> [1] "country"
#>
#> [[11]]
#> [1] "\n "No, the linebreaks do cause problems!
But notice it doesn't affect XML written to file.
write_xml(rt, "27_feed-node-xml2-roundtrip.xml")diff -b 27_feed-node-xml2.xml 27_feed-node-xml2-roundtrip.xmlEverything below here is old.
Here's my original rough pass at writing XML with xml2. Done with jimhester/xml2@04a83fe, which is now out-of-date. Code is not run.
feed <- xml_new_document() %>%
xml_add_child("feed",
xmlns = "http://www.w3.org/2005/Atom",
"xmlns:batch" = "http://schemas.google.com/gdata/batch",
"xmlns:gs" = "http://schemas.google.com/spreadsheets/2006"
)
xml_add_child(feed, "id", africa_cellsfeed)
entry <- xml_add_child(feed, "entry")
xml_add_child(entry, "batch:id", update_fodder$cell[1])
xml_add_child(entry, "batch:operation", type = "update")
xml_add_child(entry, "id", update_fodder$cell_id[1])
xml_add_child(entry, "link", rel = "edit", type = "application/atom+xml",
href = update_fodder$edit_link[1])
xml_add_child(entry, "gs:cell", row = as.character(update_fodder$row[1]),
col = as.character(update_fodder$col[1]),
inputValue = update_fodder$update_value[1])
## now I just need to do that for the remaining 35 rows of update_fodder :)
write_xml(feed, "27_feed-node-xml2.xml")Observations about the XML vs xml2 result (other than the scale up)
- Why no line breaks in the xml2 output? would be so much easier to look at
- xml2 insists on adding
<?xml version="1.0"?>as first line; will this matter? I have no idea - XML uses shorter form for elements with no content; I assume this is of no practical significance
- xml2 requires me to explicitly convert things to character (see the row and col attributes of gs:cell node)
Re setting the namespaces: the current method feels a bit weird. It feels like I should be able to provide a character vector, with possibly one unnamed element (the first one?) for the default namespace. You might also expect that the output of xml_ns() could somehow be used to set namespace? But that does not work.
foo <- xml_add_child(xml_new_document(), "feed", xml_ns(feed))
#> Error in inherits(x, "xml_document"): object 'feed' not found
xml_ns(feed)
#> Error in inherits(x, "xml_document"): object 'feed' not found
xml_ns(foo)
#> Error in inherits(x, "xml_document"): object 'foo' not found