JSON (JavaScript Object Notation) Reader Parameters

A JSON structure expression can refer to values in a JSON document. The outermost JSON element, which must be an array or an object, is always referred to by the term json, and this term must appear at the beginning of every JSON structure expression. The child elements can be referred to using JavaScript-like square bracket index operators. For example, if the outermost element is an array, the first element of the array can be referred to by the expression json[0], the second element can be referred to by the expression json[1], and so on. Likewise, if the outermost JSON element is an object, with keys "name" and "address", then the values of these keys can be referred to by the expressions json["name"] and json["address"] respectively.

These index operators can be cascaded. For example, it the outermost JSON element is an object with a key and "address" whose value is an object containing keys "city" and "province", then these values can be referred to by the expressions json["address"]["city"] and json["address"]["province"].

In order to refer to all of the values in an array or object, a wildcard index * can be used. For example, if the outermost JSON element is an array, then the expression json[*] refers to every element in the array.

A property expression is a structure expression as described above, followed by a . (dot) operator and a property name. Currently, the only supported properties are type and size. The type property returns the type of the JSON value referred to by the JSON structure expression. For example, if the outermost JSON element is an array, and the first element of the array is a string, then the expression json[0].type would have a value of string. The size property, which can only be applied to an array, returns the number of elements in the array.

A string literal expression is simply a quoted string value, such as "this is a string literal expression".

Specifies where in the JSON text the reader should look for objects representing FME features. The default query json[*] can apply to a dataset that is an array of JSON objects, each of which represents a single feature.

Specifies the JSON object key that contains the feature type of the FME feature produced from the object. If no value is provided, json_featuretype is used.

Specifies the JSON object key that contains the geometry of the FME feature produced from the object. If no value is provided, json_geometry is used.

Specifies the JSON object key that contains the coordinate system. The default value is json_ogc_wkt_crs.

Note: FME supports features without a coordinate system assigned to them. If a coordinate system is specified for the reader in FME Workbench that differs from one specified in the reader dataset, the coordinate system specified in Workbench overrides the one specified in the dataset.

Specifies the geometry format that the reader should use when converting the value of Geometry Key Name into FME geometry. Possible values are GeoJSON, OGC-WKT and None. If no value is provided, GeoJSON is used.

If set to Yes (default), FME will delete the file to which the text was downloaded after the reader has finished reading it. This field applies only if the dataset is a URL.

If checked (default), the reader decodes escape sequences when interpreting JSON text. If unchecked, escape sequences are not decoded during the reading process.

Use this parameter to expose Format Attributes in Workbench when you create a workspace:

• In a dynamic scenario, it means these attributes can be passed to the output dataset at runtime.
• In a non-dynamic scenario where you have multiple feature types, it is convenient to expose additional attributes from one parameter. For example, if you have ten feature types and want to expose the same attribute in each one, it is easier to define it once than it is to set each feature type individually in the workspace.

Using the minimum and maximum x and y parameters, define a bounding box that will be used to filter the input features. Only features that intersect with the bounding box are returned.

If all four coordinates of the search envelope are specified as 0, the search envelope will be disabled.

Select this parameter to remove any portions of exported features outside the area of interest.

The illustration below shows the results of the Search Envelope when Clip to Search Envelope is set to No on the left side and Yes on the right side.

• No: Any features that cross the search envelope boundary will be read, including the portion that lies outside of the boundary.
• Yes: Any features that cross the search envelope boundary will be clipped at the boundary, and only the portion that lies inside the boundary will be read. The underlying function for the Clip to Search Envelope function is an intersection; however, when Clip to Search Envelope is set to Yes, a clip is also performed in addition to the intersection.

Specify the authentication method to use when accessing a password-protected server.

• Basic: (default) Basic access authentication is designed to allow a client to provide credentials to a server on the assumption that the connection between them is trusted and secure. Note that any credentials passed from client to server can be easily intercepted through an insecure connection.
• Digest: Digest authentication is one of the agreed-upon methods a web server can use to negotiate credentials, such as username or password, with a user's web browser.
• NTLM: A challenge-response protocol that is used to provide compatibility with versions of Windows earlier than the Windows 2000 operating systems.
• Web Connection: Web connections provide a convenient and secure way to store and reuse previously established connection parameters. See Web Connection below.
• Single Sign-on: FME will use the credentials of the current user to authenticate the HTTP request. This authentication method currently works only on the Windows operating system.

Using Web Connections

FME Options: Web Connections