library("RPostgres")
library("rgdal")
dbGetSp <- function(dbInfo, query) {
# if(!require('rgdal')|!require(RPostgreSQL))stop('missing rgdal or RPostgreSQL')
d <- dbInfo
tmpTbl <- sprintf('tmp_table_%s',round(runif(1)*1e5))
dsn <- sprintf("PG:dbname='%s' host='%s' port='%s'",
d$dbname, "localhost", 5432
)
# dsn <- sprintf("PG:dbname='%s' host='%s' port='%s' user='%s' password='%s'",
# d$dbname,d$host,d$port,d$user,d$password
# )
# drv <- dbDriver("PostgreSQL")
# con <- dbConnect(drv, dbname=d$dbname, host='localhost', port=5432)
tryCatch({
sql <- sprintf("CREATE UNLOGGED TABLE %s AS %s", tmpTbl, query)
res <- dbSendQuery(con, sql)
nr <- dbGetInfo(res)$rowsAffected
if(nr<1){
warning('There is no feature returned.');
return()
}
sql <- sprintf("SELECT f_geometry_column from geometry_columns WHERE f_table_name='%s'",tmpTbl)
geo <- dbGetQuery(con,sql)
if(length(geo)>1){
tname <- sprintf("%s(%s)",tmpTbl,geo$f_geometry_column[1])
}else{
tname <- tmpTbl;
}
out <- readOGR(dsn,tname)
return(out)
},finally={
sql <- sprintf("DROP TABLE %s",tmpTbl)
dbSendQuery(con,sql)
dbClearResult(dbListResults(con)[[1]])
dbDisconnect(con)
})
}
library("DBI")
con <- dbConnect(RPostgres::Postgres(), dbname="spatial_db", host='localhost', port=5432)
DBI::dbSendQuery(con, "CREATE TABLE spatial_table;")
d <- list(host='localhost', dbname='spatial_db')
dbGetSp(dbInfo=d, query="SELECT * FROM spatial_table")
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