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lookup()

string lookup(string fidj-file-uri, string key [, string default = ""])

The XPath function lookup returns the value associated with the key in a database file. The database file specified by the fidj-uri can be either in JSON or SHMT format. If the key is not found, the default string will be returned.

  • fidj-file-uri: FIDJ URI pointing to a local database file. The extension of the database file must be either lowercase .json for a JSON file or lowercase .shmt for an SHMT file.
  • key: database key to search for
  • default: optional value to return if the key is not found in the database (default is an empty string "")

Using a JSON file

The JSON DB file has to be implemented as a key-value object (SHMT does this automatically):

{
  "key1": "value1",
  "key2": [1, 2, 3],
  "key3": {"k":"v"}
  ...
}

If a value is either of type object or ordered list of values (array), the value is always converted to a JSON string. By using the json-to-xml() function, the result string can be translated into a corresponding XML structure.

Example:

  <xsl:value-of select="lookup('fit://site/databases/db.json', 'key3')" />

would result in the string "{\"k\":\"v\"}".

Debugging

The lookup XPath function provides many information or error messages in the json debug channel.

Examples

...
  <xsl:value-of select="lookup('fit://project/db/my.json', 'full_name', 'John Doe')" />
...
  <xsl:value-of select="lookup('fit://site/databases/db.shmt', 'key')" />
...