如何使用自动递增的主键将数据从R写入PostgreSQL表? [英] How do I write data from R to PostgreSQL tables with an autoincrementing primary key?
问题描述
我在PostgreSQL数据库中有一个表,该表具有 BIGSERIAL
自动递增主键。使用以下命令重新创建它:
I have a table in a PostgreSQL database that has a BIGSERIAL
auto-incrementing primary key. Recreate it using:
CREATE TABLE foo
(
"Id" bigserial PRIMARY KEY,
"SomeData" text NOT NULL
);
我想通过 RPostgreSQL
软件包。在R中,数据不包含 Id
列,因为我希望数据库生成这些值。
I want to append some data to this table from R via the RPostgreSQL
package. In R, the data doesn't include the Id
column because I want the database to generate those value.
dfr <- data.frame(SomeData = letters)
这是我用来尝试写入数据的代码:
Here's the code I used to try and write the data:
library(RPostgreSQL)
conn <- dbConnect(
"PostgreSQL",
user = "yourname",
password = "your password",
dbname = "test"
)
dbWriteTable(conn, "foo", dfr, append = TRUE, row.names = FALSE)
dbDisconnect(conn)
不幸的是, dbWriteTable
引发错误:
## Error in postgresqlgetResult(new.con) :
## RS-DBI driver: (could not Retrieve the result : ERROR: invalid input syntax for integer: "a"
## CONTEXT: COPY foo, line 1, column Id: "a"
## )
错误消息不是完全清楚,但我将其解释为R试图通过 SomeData
列的内容到数据库的第一列( Id
)。
The error message isn't completely clear, but I interpret this as R trying to pass the contents of the SomeData
column to the first column in the database (which is Id
).
应如何将数据传递到PostgreSQL,以便自动生成 Id
列?
How should I be passing the data to PostgreSQL so that the Id
column is auto-generated?
推荐答案
From the thread in hrbrmstr's comment, I found a hack to make this work.
在<$ c $ postgresqlWriteTable 中的 RPostgreSQL
包,您需要替换行
sql4 <- paste("COPY", postgresqlTableRef(name), "FROM STDIN")
with
sql4 <- paste(
"COPY ",
postgresqlTableRef(name),
"(",
paste(postgresqlQuoteId(names(value)), collapse = ","),
") FROM STDIN"
)
请注意变量的引用(原始hack中不包括)传递区分大小写的列名是必需的。
Note that the quoting of variables (not included in the original hack) is necessary to pass case-sensitive column names.
以下是一个脚本来做到这一点:
Here's a script to do that:
body_lines <- deparse(body(RPostgreSQL::postgresqlWriteTable))
new_body_lines <- sub(
'postgresqlTableRef(name), "FROM STDIN")',
'postgresqlTableRef(name), "(", paste(shQuote(names(value)), collapse = ","), ") FROM STDIN")',
body_lines,
fixed = TRUE
)
fn <- RPostgreSQL::postgresqlWriteTable
body(fn) <- parse(text = new_body_lines)
while("RPostgreSQL" %in% search()) detach("package:RPostgreSQL")
assignInNamespace("postgresqlWriteTable", fn, "RPostgreSQL")
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