filepath@data 数据类型的 datajoint-matlab 实现

Question

For datajoint-matlab, #327 seems to indicate that File external storage (#143, PR #197) should be implemented in the current version. I can create a table with the datatype filepath@data, after defining the store 'data', but I get an error on insert.

Error using dj.Relvar/insert/makePlaceholder (line 244)
The field `fref` with datatype `filepath@data` is not yet supported.

Error in dj.Relvar/insert (line 334)
                    [v, placeholder] = makePlaceholder(i,
                    tuple.(header.attributes(i).name));

Is this still not implemented, or is the error-checking here just stopping me from using it? Happy to provide more details on the test if needed.

Answer 1

Maintainer for DataJoint here. Looks like there is a bit of confusion so let's see if I can help to bring some clarity. Hope to use this discussion as a resource to improve the documentation.

DataJoint provides a few DataJoint-only datatypes . Of these types, we identify the ones associated with external storage by embedding an @ symbol. We classify each part of the type as <datatype>@<store> . Essentially with these types, information (ie datatype ) is stored remotely in an object store (ie a store ) with proper reference links within the relational database and client configuration for access.

For datatype , there are currently 3 options:

• blob : Equivalent to a blob type but for external stores. Currently, this type is supported both in datajoint-python and most recently in datajoint-matlab .
• attach : A special type that captures file content as binary information but does not preserve any path information. Currently, this type is supported only in datajoint-python . Documentation is available for this type in File Attachment Datatype section.
• filepath : A special type that captures file content as binary information and includes path (along with file name) detail. Currently, this type is in preview in datajoint-python requiring it to be enabled. Documentation is available for this type in Filepath Datatype section. See note in documentation to enable it.

For store , there is an External Store section in the documentation. Multiple stores can be configured as a mapping located under the stores key in dj.config . For MATLAB, see help('dj.config') for examples and in Python, refer to the docs for attach and filepath above.

Stores currently support 2 protocols:

• s3 : Stores objects in an S3 bucket. Currently, this store is supported both in datajoint-python and most recently in datajoint-matlab .
• file : Stores files in a directory accessible via the filesystem on the client. Currently, this store is supported both in datajoint-python and most recently in datajoint-matlab .

Issue #143 and PR's #197 , #327 that you've mentioned refer to efforts in implementing file , s3 stores for the blob datatype in DataJoint MATLAB. The error you've experienced is expected and a simple placeholder until we support the other 2 datatypes in DataJoint MATLAB.