Toolkit - Dynamic Content Queries

This post if part of a series about the File System Toolkit - a custom content delivery API for SDL Tridion.

This post presents the Dynamic Content Query capability. The requirements for the Toolkit API are that it should be able to provide CustomMeta queries, pagination, and sorting -- all on the file system, without the use third party tools (database, search engines, indexers, etc). Therefore I had to implement a simple database engine and indexer -- which is described in more detail in post Writing My Own Database Engine.

The querying logic does not make use of cache. This means the query logic is executed every time. When models are requested, the models are however retrieved using the ModelFactory and those are cached.

Query Class

This is the main class for dynamic content queries. It is the entry point into the execution logic of a query. The class takes as parameter a Criterion (presented below) which triggers the execution of query in all sub-criteria of a Criterion object.

Class Query provides three main method: executeQuery, executeComponentQuery and executePageQuery, presented below. Each of these method return a list of items, paginated and sorted against the given parameters.

Method executeQuery

This method returns an list of Strings representing the TcmUris of the result. In terms of sorting, this is the most inefficient method because it first has to retrieve Component and Page models for all TcmUris, then sort them, then apply pagination on them and return only the result.

public List<String> executeQuery() {
    List<String> uris = new ArrayList<>(criterion.executeQuery());

    totalItemCount = uris.size();
    uris = applyPagination(uris);

    return uris;
}

Method executeComponentQuery

The method returns a list of ComponentMeta models that match the specified criteria. The method delegates the executeQuery call to the given Criterion and applies filter to item types Components only.

public List<ComponentMeta> executeComponentQuery() {
    List<String> uris = new ArrayList<>(criterion.executeQuery(
        new FilterImpl(ItemTypes.COMPONENT)));
    List<ComponentMeta> result = new ArrayList<>(uris.size());
    for (String uri : uris) {
        TcmUri tcmUri = new TcmUri("tcm:" + uri);
        ComponentMeta componentMeta = modelFactory.getModel(tcmUri);
        if (componentMeta != null) {
            result.add(componentMeta);
        }
    }

    totalItemCount = result.size();
    Collections.sort(result, sorter);
    result = applyPagination(result);

    return result;
}

Method executePageQuery

The method returns a list of PageMeta models that match the specified criteria.

public List<PageMeta> executePageQuery() {
    List<String> uris = new ArrayList<>(criterion.executeQuery(
        new FilterImpl(ItemTypes.PAGE)));
    List<PageMeta> result = new ArrayList<>(uris.size());

    for (String uri : uris) {
        TcmUri tcmUri = new TcmUri("tcm:" + uri);
        PageMeta pageMeta = modelFactory.getModel(tcmUri);
        if (pageMeta != null) {
            result.add(pageMeta);
        }
    }
    totalItemCount = result.size();

    if (sorter != null) {
        Collections.sort(result, sorter);
    }

    result = applyPagination(result);
    return result;
}