Indexes: Additional Assemblies

• Index capabilities can be expanded by importing whole libraries with useful classes and methods that can then be used in the index syntax.
  Additional Assemblies make it very easy to import assemblies from:

  • NuGet
  • Runtime
  • Local file

• Indexes can be enhanced with capabilities like machine learning image recognition or full text searching in Office files.

• This feature is similar to the Additional Sources feature, that can be used to add methods and classes to an index in the form of a file or pure text.
  These two features can be used together: an index's Additional Sources code has access to all of the index's Additional Assemblies.

• In this page:

  • Syntax
  • Examples
    • Basic Example
    • Complex Example
    • Pre-Release Packages

Syntax

Additional assemblies are defined using the AdditionalAssembly object.

public class AdditionalAssembly
{
  public static AdditionalAssembly FromRuntime(string assemblyName, 
                                               HashSet<string> usings = null);

  public static AdditionalAssembly FromPath(string assemblyPath, 
                                            HashSet<string> usings = null);

  public static AdditionalAssembly FromNuGet(string packageName, 
                                             string packageVersion, 
                                             string packageSourceUrl = null, 
                                             HashSet<string> usings = null);
}

Parameter	Type	Description
assemblyName	string	The name of an assembly to import from runtime
assemblyPath	string	Local path to an assembly
packageName	string	Name of a NuGet package to import
packageVersion	string	The version number of the NuGet package - optional
packageSourceUrl	string	The URL of the package's original source - optional
usings	HashSet<string>	A set of namespaces to attach to the compiled index with using - optional
The AdditionalAssemblys are collected in AdditionalAssemblies, a property of
IndexDefinition:

public HashSet<AdditionalAssembly> AdditionalAssemblies;

Examples

Basic Example

This index is able to use the method GetFileName() from the class Path because the namespace System.IO has been imported as an additional assembly. It takes a string file path and retrieves just the file name and extension.

var runtimeindex = new IndexDefinition
{
  Name = "Dog_Pictures",
  Maps = { @"
      from user in docs.Users
      let fileName = Path.GetFileName(user.ImagePath)
      where fileName = ""My_Dogs.jpeg""
      select new {
          user.Name,
          fileName
      }"
  },
  AdditionalAssemblies = {
      AdditionalAssembly.FromRuntime("System.IO")
  }
};

Complex Example

This index uses a machine learning algorithm imported from NuGet that can recognize the contents of images and classify them with an appropriate tag. These tags are then stored in the index just like any other term.

store.Maintenance.Send(new PutIndexesOperation(new IndexDefinition
{
  Name = "Photographs/Tags",
  Maps =
  {
      @"
      from p in docs.Photographs
      let photo = LoadAttachment(p, ""photo.png"")
      where photo != null
      let classified =  ImageClassifier.Classify(photo.GetContentAsStream())
      select new {
          e.Name,
          Tag = classified.Where(x => x.Value > 0.75f).Select(x => x.Key),
          _ = classified.Select(x => CreateField(x.Key, x.Value))
      }"
  },
  AdditionalSources = new System.Collections.Generic.Dictionary<string, string>
  {
      {
          "ImageClassifier", 
          @"
          public static class ImageClassifier
          {
              public static IDictionary<string, float> Classify(Stream s)
              {
                  // returns a list of descriptors with a
                  // value between 0 and 1 of how well the
                  // image matches that descriptor.
              }
          }"
      }

  },
  AdditionalAssemblies =
  {
      AdditionalAssembly.FromRuntime("System.Memory"),
      AdditionalAssembly.FromNuGet("System.Drawing.Common", "4.7.0"),
      AdditionalAssembly.FromNuGet("Microsoft.ML", "1.5.2")
  }
}));

Pre-Release Packages

Additional assemblies are allowed to include pre-release packages.

AdditionalAssemblies = {
  AdditionalAssembly.FromNuGet("FlexiMvvm.Common.PreRelease", "0.10.8-prerelease")
}