Infusion IoC API

Whilst Infusion's IoC is primarily a declarative system, operated by a declarative dialect of JSON configuration, there are a few language-level APIs which are useful in dealing with the system. Some of these are externalisable in that there is a reasonable semantic for operating them from outside the JavaScript VM housing the component tree - these special APIs are grouped under the heading Nexus API methods, named after the Nexus component that will shortly be built around them.

IoC utility methods


  • component: {Component} The component whose global path is required
  • Returns: {Array of String} The component's global path, as an array of path segments

Each instantiated component in the Infusion system has a stable base path in the system's global component tree. Records about the component are held in Infusion's instantiator where the path and numerous other details can be looked up. This utility method accepts a currently instantiated (not destroyed) component and returns its path as a set of parsed array segments. This information can be very useful for making calculations about the geometry of component trees - that is, which components are descended from which others and which are siblings, etc.


Retrieves a component by global path.

  • path {String|Array of String} The global path of the component to look up
  • Returns: The component at the specified path, or undefined if none is found

fluid.queryIoCSelector(root, selector[, flat])

Query for all components matching a selector in a particular tree.

  • root {Component} The root component at which to start the search. A reasonable choice for this can be fluid.rootComponent although such global searches can be very slow. A more reasonable choice will be some particular component in the tree whose descendents are of interest.
  • selector {String} An IoCSS selector, in form of a string. Note that since selectors supplied to this function implicitly match downwards, they need not contain the "head context" followed by whitespace required in the distributeOptions form. E.g. simply fluid.viewComponent will match all viewComponents below the root.
  • flat {Boolean} [optional] true if the search should just be performed at top level of the component tree. Note that with flat=true this search will scan every component in the tree and may well be very slow.

fluid.makeGradeLinkage(linkageName, inputNames, outputNames)

Registers a grade into the system, and create a global instance of it, which ensures that any components where the grades listed in inputNames co-occur (that is, occur attached to the same component) will also be supplied the grades listed in outputNames. This is a shorthand for an effect that the user can achieve for themselves by constructing an instance of a component holding a distributeOptions block globally targetting the co-occuring grades.

  • linkageName {String} The grade name which will hold the required options distribution. The component instance's global name will be derived from this grade name via fluid.typeNameToMemberName.
  • inputNames {Array of String} The list of grade names which must co-occur in a single component in order to trigger the addition of outputNames.
  • outputNames {String or Array of String} The grade names which will be added to any component in which the inputNames co-occur.

fluid.expand(material, that)

Expands some options material in the context of a particular component - any IoC References and expanders held at any depth in the material will be expanded to hold their resolved contents. The source material will not be modified.

  • material {Object} The configuration material to be expanded
  • that {Component} The component in whose context the material is to be expanded
  • Returns: {Object} An expanded version of the input material.

fluid.getForComponent(component, path)

This is a fairly interesting method. During the instantiation of an IoC component tree, the framework's "focus of attention" moves around the tree in a data-driven way. If an IoC reference is seen to a particular path, this will direct attention to instantiate the material referenced by the path. fluid.getForComponent is the method used internally by the framework in order to ensure that any referenced material has actually been instantiated before the results from any IoC reference are filled in in the expanded options material. You can use this method too, in order to make sure that any member of a component has been instantiated before you look at it. This should not normally be necessary - and the use of this API only makes sense during a construction "fit" - during the "semi-static period", you can assume that all members of all visible components are concrete.

This is an analogue of the API fluid.get for use during the "ginger construction process".

  • component {Component} The component whose resolved member is required
  • path {String|Array of String} The path within the component which is to be resolved
  • Returns: {Any} The fully observed value held at path of component component.

fluid.resolveContext (context, that)

Another method for enthusiasts. Given a particular IoC Context, determine which (if any) component in the tree it refers to, from the point of view of component that.

  • context {String} The context to be resolved. For example, in an IoC reference of the form "{myContext}.myPath1.myPath2", the context is myContext.
  • that {Component} The component from whose point of view the context is to be resolved
  • Returns: {Component|None} Returns the component to which the context refers, or undefined if the reference cannot be resolved.

fluid.parseContextReference(reference) {

Parse an IoC reference of the form "{myContext}.myPath1.myPath2" into an object form. In this case, for example, the output would be

    context: "myContext", 
    path: "myPath1.myPath2"

From here it is a simple matter to resolve them in a DIY fashion with reference to the APIs fluid.resolveContext and fluid.getForComponent or fluid.get.

  • reference {String} An IoC reference expressed as a String
  • Returns: {Object} The parsed form of the reference, with the following fields:
    • context {String} The context portion of the IoC reference
    • path {String} The path portion of the IoC reference


This path holds the global instantiator which holds all the records for Infusion's IoC system. Whilst any methods on this object should not be called by applications, there are many entries in here that can aid debugging, especially the members instantiator.pathToComponent which holds a mapping for every instantiated component from its global path in the component tree, and instantiator.idToShadow which holds a mapping from every component's id to its shadow record which holds many useful pieces of bookkeeping, including the mergeOptions structure which can be used to inspect the details of the options merging process resulting in the component's final options.


Holds the global root component for the global instantiator's component tree.

Nexus API methods

fluid.construct(path, options[, instantiator])

Construct a component with the supplied options at the specified path in the component tree. The parent path of the location must already be a component.

  • path {String|Array of String} Path where the new component is to be constructed, represented as a string or array of segments
  • options {Object} Top-level options supplied to the component - must at the very least include a field type holding the component's type. Note that these are expressed in the future-compatible post-FLUID-5750 format with type alongside the component's options rather than at a higher nested level as is currently required in local configuration supplied as subcomponents.
  • instantiator {Instantiator} [optional] The instantiator holding the component to be created - if blank, the global instantiator will be used

fluid.destroy(path[, instantiator])

Destroys a component held at the specified path. The parent path must represent a component, although the component itself may be nonexistent.

  • path {String|Array of String} Path where the component is to be destroyed, represented as a string or array of segments
  • instantiator {Instantiator} [optional] The instantiator holding the component to be destroyed - if blank, the global instantiator will be used


This method is included in the Nexus API since the effects of the ContextAwareness API fluid.constructSingle need to be replicable from outside the process. This API assists users to compute the name at which the IoC system will be expecting an "adaptation" component with a particular typeName to be instantiated as a member of the global root component. Note that the period character . is not supported within a component member name.

  • typeName {String} The "principal type name" of the component which should be used to compute its global name for the purposes of a fluid.constructSingle adaptation honoured through fluid.construct.
  • Returns: {String} The required member name of the global root component