View source on GitHub
|
Provides a read-only file-like interface to a blobstore blob.
Inherits From: expected_type
google.appengine.ext.blobstore.BlobReader(
blob, buffer_size=131072, position=0
)
Args | |
|---|---|
blob
|
The blob key, blob info, or string blob key to read from. |
buffer_size
|
The minimum size to fetch chunks of data from blobstore. |
position
|
The initial position in the file. |
Raises | |
|---|---|
ValueError
|
If a BlobKey, BlobInfo, or string blob key is not
supplied.
|
Attributes | |
|---|---|
blob_info
|
Returns the BlobInfo for this file.
|
closed
|
Determines whether a file is closed. |
Methods
close
close()
Closes the file.
A closed file cannot be read or written to anymore. An operation that
requires that the file to be open will raise a ValueError after the file
has been closed. Calling close() more than once is allowed.
flush
flush()
next
next()
Returns the next line from the file.
| Returns | |
|---|---|
A string, terminated by \\n. The last line cannot end with \\n. If the
end of the file is reached, an empty string will be returned.
|
| Raises | |
|---|---|
StopIteration
|
If there are no further lines to read. |
read
read(
size=-1
)
Reads at most size bytes from the file.
Fewer bytes are read if the read hits the end of the file before obtaining
size bytes. If the size argument is negative or omitted, all data is
read until the end of the file is reached. The bytes are returned as a
string object. An empty string is returned immediately when the end of the
file is reached.
Calling read() without specifying a size is likely to be dangerous, as
it might read excessive amounts of data.
| Args | |
|---|---|
size
|
Optional. The maximum number of bytes to read. When omitted,
read() returns all remaining data in the file.
|
| Returns | |
|---|---|
| The read data, as a string. |
readline
readline(
size=-1
)
Reads one entire line from the file.
A trailing newline character is kept in the string but can be absent when a
file ends with an incomplete line. If the size argument is present and
non-negative, it represents a maximum byte count, including the trailing
newline and an incomplete line might be returned. An empty string is
returned immediately only when the end of the file is reached.
| Args | |
|---|---|
size
|
Optional. The maximum number of bytes to read. |
| Returns | |
|---|---|
| The read data, as a string. |
readlines
readlines(
sizehint=None
)
Reads until the end of the file using readline().
A list of lines read is returned.
If the optional sizehint argument is present, instead of reading up to the
end of the file, whole lines totalling approximately sizehint bytes are
read, possibly after rounding up to an internal buffer size.
| Args | |
|---|---|
sizehint
|
A hint as to the maximum number of bytes to read. |
| Returns | |
|---|---|
| A list of strings, each being a single line from the file. |
seek
seek(
offset, whence=SEEK_SET
)
Sets the file's current position, like stdio's fseek()_.
| Args | |
|---|---|
offset
|
The relative offset to seek to. |
whence
|
Optional; defines to what value the offset is relative. This
argument defaults to os.SEEK_SET or 0 to use absolute file
positioning; other valid values are os.SEEK_CUR or 1 to seek
relative to the current position and os.SEEK_END or 2 to seek
relative to the end of the file.
|
.. _fseek(): http://www.cplusplus.com/reference/cstdio/fseek/
tell
tell()
Retrieves the file's current position, like stdio's ftell()_.
| Returns | |
|---|---|
| The file's current position. |
.. _ftell(): http://www.cplusplus.com/reference/cstdio/ftell/
truncate
truncate(
size
)
Raises an error if you attempt to truncate the file.
| Args | |
|---|---|
size
|
The size that you are attempting to truncate to. |
| Raises | |
|---|---|
IOError
|
If you attempt to truncate a file in BlobReader.
|
write
write(
str
)
Raises an error if you attempt to write to the file.
| Args | |
|---|---|
str
|
The string that you are attempting to write. |
| Raises | |
|---|---|
IOError
|
If you attempt to write to a file in BlobReader.
|
writelines
writelines(
sequence
)
Raises an error if you attempt to write to the file.
| Args | |
|---|---|
sequence
|
The sequence of strings that you are attempting to write. |
| Raises | |
|---|---|
IOError
|
If you attempt to write lines to a file in BlobReader.
|
__enter__
__enter__()
Attempts to open the file.
| Returns | |
|---|---|
| The open file. |
__exit__
__exit__(
exc_type, exc_value, traceback
)
Closes the file.
__iter__
__iter__()
Retrieves a file iterator for this BlobReader.
| Returns | |
|---|---|
The file iterator for the BlobReader.
|
Class Variables | |
|---|---|
| SEEK_CUR |
1
|
| SEEK_END |
2
|
| SEEK_SET |
0
|