DependencyResolver

Helper class for resolving component dependencies.

Implements: IReferences

Description

The DependencyResolver is a helper class that allows you to resolve component dependencies. It is configured to resolve named dependencies by a specific locator.

Important points:

  • During deployment the dependency locator can be changed. This mechanism can be used to clarify a specific dependency among several alternatives. Typically components are configured to retrieve the first dependency that matches a logical group, type and version. However, if the container contains more than one instance and the resolution has to be specific about those instances; they can be given a unique name, and the dependency resolvers can be reconfigured to retrieve dependencies according to their name.

Configuration parameters

  • dependencies:
    • [dependency name 1]: Dependency 1 locator (descriptor)
    • …
    • [dependency name N]: Dependency N locator (descriptor)

References

References must match configured dependencies.

Constructors

NewDependencyResolverWithParams

Creates a new instance of the dependency resolver.

NewDependencyResolverWithParams(ctx context.Context, config *conf.ConfigParams, references IReferences) *DependencyResolver

  • ctx: context.Context - operation context.
  • config: *conf.ConfigParams - (optional) default configuration where key is dependency name and value is locator (descriptor)
  • references: IReferences - (optional) default component references

NewDependencyResolverFromTuples

Creates a new DependencyResolver from a list of key-value pairs called tuples where key is dependency name and value the depedency locator (descriptor).

NewDependencyResolverFromTuples(ctx context.Context, tuples …any) *DependencyResolver

  • ctx: context.Context - operation context.
  • tuples: …any - list of values where odd elements are dependency name and the following even elements are dependency locator (descriptor)

NewDependencyResolver

Creates a new instance of the dependency resolver.

NewDependencyResolver() *DependencyResolver

Methods

Configure

Configures the component with specified parameters.

(c *DependencyResolver) Configure(ctx context.Context, config *conf.ConfigParams)

  • ctx: context.Context - operation context.
  • config: *conf.ConfigParams - configuration parameters to set.

Find

Finds all matching dependencies by their name.

(c *DependencyResolver) Find(name string, required bool) ([]any, error)

  • name: string - dependency name to locate.
  • required: bool - true to raise an exception when no dependencies are found.
  • returns: ([]any, error) - list of found dependencies

GetOneOptional

Gets one optional dependency by its name.

(c *DependencyResolver) GetOneOptional(name string) any

  • name: string - dependency name to locate.
  • returns: any - dependency reference or nil of the dependency was not found

GetOneRequired

Gets one required dependency by its name. At least one dependency must present. If the dependency was found it throws a ReferenceError

(c *DependencyResolver) GetOneRequired(name string) (any, error)

  • name: string - dependency name to locate.
  • returns: (any, error) - dependency reference

GetOptional

Gets all optional dependencies by their name.

(c *DependencyResolver) GetOptional(name string) []any

  • name: string - dependency name to locate.
  • returns: []any - list with found dependencies or empty list of no dependencies was found.

GetRequired

Gets all required dependencies by their name. At least one dependency must be present. If no dependencies were found it throws a ReferenceError

(c *DependencyResolver) GetRequired(name string) ([]any, error)

  • name: string - dependency name to locate.
  • returns: ([]any, error) - list with found dependencies.

Put

Adds a new dependency into this resolver.

(c *DependencyResolver) Put(ctx context.Context, name string, locator any)

  • ctx: context.Context - operation context.
  • name: string - dependency’s name.
  • locator: any - locator to find the dependency by.

SetReferences

Sets the component references. References must match configured dependencies.

(c *DependencyResolver) SetReferences(ctx context.Context, references IReferences)

  • ctx: context.Context - operation context.
  • references: IReferences - references to set.

Examples

TODO: add example

See also