Description Usage Arguments Details Value See Also Examples
Read raw data from a mongo.gridfile. The data read may span multiple chunks.
1 | mongo.gridfile.read(gridfile, size)
|
gridfile |
A (mongo.gridfile) object. |
size |
(as.double) The number of bytes to read. |
A mongo.gridfile file maintains a current read position which is advanced by the size of each read. This position is initially at offset 0.
Since this function returns raw data, you may want to use R's
readBin()
to unpack it.
(raw) The data read from emphgridfile. The length of this vector may
be less than the requested size if there was not enough data remaining to be
read. This length could also be 0 if an error occured during the operation.
Check mongo.get.err()
of the associated mongo connection
object in this case.
mongo.gridfs
,
mongo.gridfs.find
,
mongo.gridfile,
mongo.gridfile.get.descriptor
,
mongo.gridfile.get.filename
,
mongo.gridfile.get.length
,
mongo.gridfile.get.chunk.size
,
mongo.gridfile.get.chunk.count
,
mongo.gridfile.get.content.type
,
mongo.gridfile.get.upload.date
,
mongo.gridfile.get.md5
,
mongo.gridfile.get.metadata
,
mongo.gridfile.get.chunk
,
mongo.gridfile.get.chunks
,
mongo.gridfile.seek
,
mongo.gridfile.pipe
.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | mongo <- mongo.create()
if (mongo.is.connected(mongo)) {
gridfs <- mongo.gridfs.create(mongo, "grid")
mongo.gridfs.store.file(gridfs, "tests/test.R", "test.R")
gf <- mongo.gridfs.find(gridfs, "test.R")
if( !is.null(gf)){
mongo.gridfile.seek(gf, 256*256*5)
data <- mongo.gridfile.read(gf, 16384)
mongo.gridfile.destroy(gf)
}
mongo.gridfs.destroy(gridfs)
}
|
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