JSON Reader

This node reads the .json file and parses it as JSON value.

This node can access a variety of different file systems. More information about file handling in KNIME can be found in the official File Handling Guide.

Options

Settings

Read from
Select a file system which stores the data you want to read. There are four default file system options to choose from:
  • Local File System: Allows you to select a file/folder from your local system.
  • Mountpoint: Allows you to read from a mountpoint. When selected, a new drop-down menu appears to choose the mountpoint. Unconnected mountpoints are greyed out but can still be selected (note that browsing is disabled in this case). Go to the KNIME Explorer and connect to the mountpoint to enable browsing. A mountpoint is displayed in red if it was previously selected but is no longer available. You won't be able to save the dialog as long as you don't select a valid i.e. known mountpoint.
  • Relative to: Allows you to choose whether to resolve the path relative to the current mountpoint, current workflow or the current workflow's data area. When selected a new drop-down menu appears to choose which of the three options to use.
  • Custom/KNIME URL: Allows to specify a URL (e.g. file://, http:// or knime:// protocol). When selected, a spinner appears that allows you to specify the desired connection and read timeout in milliseconds. In case it takes longer to connect to the host / read the file, the node fails to execute. Browsing is disabled for this option.
To read from other file systems, click on ... in the bottom left corner of the node icon followed by Add File System Connection port . Afterwards, connect the desired file system connector node to the newly added input port. The file system connection will then be shown in the drop-down menu. It is greyed out if the file system is not connected in which case you have to (re)execute the connector node first. Note: The default file systems listed above can't be selected if a file system is provided via the input port.
Mode
Select whether you want to read a single file or multiple files in a folder. When reading files in a folder, you can set filters to specify which files and subfolders to include (see below).
Filter options
Only displayed if the mode Files in folder is selected. Allows to specify which files should be included according to their file extension and/or name. It is also possible to include hidden files. The folder filter options enable you to specify which folders should be included based on their name and hidden status. Note that the folders themselves will not be included, only the files they contain.
Include subfolders
If this option is checked, the node will include all files from subfolders that satisfy the specified filter options. If left unchecked, only the files in the selected folder will be included and all files from subfolders are ignored.
File, Folder or URL
Enter a URL when reading from Custom/KNIME URL, otherwise enter a path to a file or folder. The required syntax of a path depends on the chosen file system, such as "C:\path\to\file" (Local File System on Windows) or "/path/to/file" (Local File System on Linux/MacOS and Mountpoint). For file systems connected via input port, the node description of the respective connector node describes the required path format. You can also choose a previously selected file/folder from the drop-down list, or select a location from the "Browse..." dialog. Note that browsing is disabled in some cases:
  • Custom/KNIME URL: Browsing is always disabled.
  • Mountpoint: Browsing is disabled if the selected mountpoint isn't connected. Go to the KNIME Explorer and connect to the mountpoint to enable browsing.
  • File systems provided via input port: Browsing is disabled if the connector node hasn't been executed since the workflow has been opened. (Re)execute the connector node to enable browsing.
The location can be exposed as or automatically set via a path flow variable.
Output column name
Name of the output column
Select with JSONPath
Select a part of the read JSON if checked
JSONPath
The part to select from the input JSON. Using JSONPath preferably with a single result. (For multiple results new rows will be created from them.)
Fail if path not found
If checked, execution will fail if no such part found. If unchecked and not found, the result will be an empty file.
Allow comments in json files
When selected, /* ... */ and the line comments // , # are interpreted as comments and get ignored instead of causing errors
Path column
If checked, the node will append a path column with the provided name to the output table. This column contains for each row which file it was read from. The node will fail if adding the column with the provided name causes a name collision with any of the columns in the read table.

Limit Rows

Skip first data rows
If enabled, the specified number of valid data rows are skipped.
Limit data rows
If enabled, only the specified number of data rows are read.

Input Ports

Icon
The file system connection.

Output Ports

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Table with the read JSON values

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