Page History

...

JSON does not provide any type information for the values it contains.  For a configuration database, this can be problematic, as some numeric values might be limited to integers or even a small set of integers.  Therefore, additional information is added to the JSON configuration object to provide type information.  Any field name ending in ":RO" is considered to be read-only and will not be displayed by the graphical editor.  An additional key, ":types:" will be added to the top level dictionary.  This key maps to a dictionary with roughly the same structure as the JSON object, except that instead of containing values, the dictionary contains type information.  This information is either:

...

• setInfo(detType=None, detName=None, detId=None, doc=None)
  Set the top-level reserved keys to the specified values.
• setAlg(alg, version=[0,0,0], doc="")
  Set the top-level reserved "alg" key to a dictionary containing the arguments.
• set(name, value, type="INT32", override=False, append=False)
  The "name" parameter is a "flattened" name with dot-separated fields.  XXX.  Each field is used as a dictionary key or list index in turn to describe a particular value in the JSON object.  (As a bit of syntactic sugar, list indices may be separated from the previous field by an underscore or a dot.  That is "a.6.b" or "a_6.b" are equivalent.)    This routine sets the referred to value to the value parameter with the specified type.  If the hierarchy already exists and has a different type, an exception is thrown unless override is True, in which case the hierarchy and type is overwritten.  In the event that name refers to a list, append controls whether the list should be overwritten or appended to.
• typed_json()
  Return a dictionary representing a typed JSON object (with the ":types:" key, etc.).
• get(name, withtype=False)
  The "name" parameter is a flattened name as described for the set method.  The current value of this name in the hierarchy is returned.  If withtype is True, values that are basic types will return a tuple, the first element of which is a string which names the basic type and the second element is the value.
• getenumdict(name, reverse=False)
  If name is not a defined enumeration type, return None.  Otherwise, return a dictionary with the enumeration mapping.  If reverse is False, the mapping is from names to integers, and if it is True, the mapping is fromintegers to names.
• define_enum(name,value)
  This method defines a new enumeration type, name.  value is a dictionary mapping names of the enumeration type to integer values.

The typed_json module also has a few helper functions to deal with typed JSON dictionaries.

• getType(dict, name) returns the type of the value referred to by the flattened name, throwing an error if dict does not have any such value.
• getValue(dict, name) returns the value referred to by the flattened name, throwing an error if dict does not have any such value.
• updateValue(dict, name, value) stores a new value into the typed JSON dict referred to by name.  value is always a string.  Numeric values are converted, and array values are space-separated.  0 is returned on success, and non-zero values indicate an error.