Query Builder

The query builder is a library that helps interpret or construct a VQLL query.
VQLL is a Lisp-style grammar that writes values out in JSON arrays.

Usage

Include the following package dependencies in the project:

<ItemGroup>
    <PackageReference Include="MicroFocus.CafApi.QueryBuilder" Version="*" />
    <PackageReference Include="MicroFocus.CafApi.QueryBuilder.Mapper" Version="*" />
    <PackageReference Include="MicroFocus.CafApi.QueryBuilder.Matcher" Version="*" />
    <PackageReference Include="MicroFocus.CafApi.QueryBuilder.Vqll.Parsers.SystemJson" Version="*" />
</ItemGroup>

VQLL Parser

The QueryBuilder.Parsers.SystemJson is a library that helps create field filters/clauses by analyzing a query string that conforms to VQLL.

Filter conversions

The QueryBuilder.Mapper module can be used to change the type parameter of Filter objects by applying a mapping function lazily.

Filter matching

The QueryBuilder.Matcher is a library that allows users to match a document to a Filter.

Matching a document to filter

To match a document to a filter, first create a filter, and then invoke the filter.IsMatch method mapping the Filter<string> to a Filter<IMatcherFieldSpec> using the filter.Map method.

Sample application

A sample document is represented by a Dictionary which has field names mapped to a list of string field values

var document = new Dictionary<string, List<string>>()
{
    { "ID", new List<string>() { "1" } },
    { "IS_ROOT", new List<string>() { "true" } },
    { "CLASSIFIED", new List<string>() { "true" } },
    { "COLLECTION_STATUS", new List<string>() { "CONTENT" } },
    { "FILE_PATH", new List<string>() {
        "//alpha-agent04/EnronData/Sent Items/enron guaranty (forest oil - conf).doc" } },
    { "REPOSITORY_ID", new List<string>() { "100" } },
    { "TITLE", new List<string>() { "enron guaranty (forest oil - conf).doc" } },
    { "CONTENT", new List<string>() {
        "Guarantor hereby irrevocably and unconditionally guarantees timely payment" } }
}

In VQLL a Title equals "some string" is specified as

var vqll = @"[""=="", ""TITLE"", ""Sciullo Properties -- Appraisal""]",

Parse the vqll criteria which is a json string and get a JsonNode

var vqllJsonNode = JsonNode.Parse(vqll);

Interpret the vqll and create a Filter object

Filter<string> filter = SystemJsonFilterReader.ReadFromJsonArray(vqllJsonNode);

Map the 'string' type Filter object to a 'MapKeyMatcherFieldSpec' type Filter. The 'fields' specified in the filter which are strings are mapped to "keys" in a Dictionary representation of a document

bool? isMatch = filter.Map(x => new MapKeyMatcherFieldSpec(x)).IsMatch(document);

The Filter.IsMatch(document) function follows the three-valued logic and returns

• true if the document matches the filter
• false if the document does not match the filter
• null if fields in the filter are not present in the document and the filter cannot be evaluated

Sample MatcherFieldSpec

public sealed class MapKeyMatcherFieldSpec : IMatcherFieldSpec<Dictionary<string, List<string>>>
{
    private readonly string _key;

    public MapKeyMatcherFieldSpec(string key)
    {
        _key = key;
    }

    public IEnumerable<IMatcherFieldValue>? GetFieldValues(Dictionary<string, List<string>> document)
    {
        return document.TryGetValue(_key, out var value)
            ? value.Select(value => new MatcherFieldValue(value))
            : null;
    }

    public bool IsCaseInsensitive => true;

    public bool IsTokenizedPath => false;

    class MatcherFieldValue : IMatcherFieldValue
    {
        private readonly string _value;
        public MatcherFieldValue(string value)
        {
            _value = value;
        }

        public string StringValue => _value;
        public bool IsReference => false;
    }
}