Skip to content

Latest commit

 

History

History
248 lines (175 loc) · 8.15 KB

Querying.md

File metadata and controls

248 lines (175 loc) · 8.15 KB
Raw

Querying

Simple query

This is the simplest 'query object' in SolrNet. Whatever you give it is passed straight to Solr's q parameter

ISolrOperations<Product> solr = ...
var products1 = solr.Query(new SolrQuery("lucene")); // search for "lucene" in the default field
var products2 = solr.Query(new SolrQuery("name:solr")); // search for "solr" in the "name" field

Query by field

This allows you to define field name and value separately:

ISolrOperations<Product> solr = ...
var products = solr.Query(new SolrQueryByField("name", "solr")); // search for "solr" in the "name" field

It also has the benefit that it handles special character escaping for you.

(SolrNet 0.4.0) You can disable character escaping by setting Quoted = false:

var q = new SolrQueryByField("name", "John*") { Quoted = false };

Query by range

Creates a range query:

ISolrOperations<Product> solr = ...
var products = solr.Query(new SolrQueryByRange<decimal>("price", 100m, 250.50m)); // search for price between 100 and 250.50

Query by list of values

var q = new SolrQueryInList("name", "solr", "samsung", "maxtor");

is the same as name:solr OR name:samsung OR name:maxtor

"Any value" query

It's often convenient to see what documents have a field defined or not:

var q = new SolrHasValueQuery("name");

is equivalent to the Solr query name:[* TO *]

Query by distance

(SolrNet 0.4.0)

Creates a geofilt or bbox filter on a LatLonType field.

Examples:

// default accuracy is CalculationAccuracy.Radius (higher accuracy)
var q = new SolrQueryByDistance("store", pointLatitude = 45.15, pointLongitude = -93.85, distance = 5);

var q = new SolrQueryByDistance("store", pointLatitude = 45.15, pointLongitude = -93.85, distance = 5, accuracy = CalculationAccuracy.BoundingBox);

See the Solr wiki for more information.

Query operators

You can use the && and || operators to connect queries, with the expected results:

var q = new SolrQuery("solr") && new SolrQuery("name:desc");

generates the query solr AND name:desc

The plus (+) operator is also overloaded. It concatenates the queries and leaves the actual operator to the default as specified in Solr's configuration.

var q = new SolrQuery("solr") + new SolrQuery("name:desc");

creates the query solr name:desc

To negate a query, you can call Not() on it or just use the ! operator:

var q = !new SolrQuery("solr");

creates the query -solr

Finally, the minus (-) operator:

var q = new SolrQuery("solr") - new SolrQuery("name:desc"); // solr - name:desc

which is equivalent to (and more intuitive than):

var q = new SolrQuery("solr") + !new SolrQuery("name:desc"); // solr - name:desc

Alternatively, if you have a list of queries you want to aggregate you can use SolrMultipleCriteriaQuery. For example:

new SolrMultipleCriteriaQuery(new[] {new SolrQuery("1"), new SolrQuery("2")})

is the same as:

new SolrQuery("1") + new SolrQuery("2")

You can also define what operators to use to join these queries, e.g:

new SolrMultipleCriteriaQuery(new[] {new SolrQuery("1"), new SolrQuery("2")}, "AND")

Boosting

You can boost particular queries by calling Boost(), for example:

var q = new SolrQuery("name:desc").Boost(2); // (name:desc)^2

See the Lucene docs for more information about boosting.

Filter queries

Filter queries can be used to specify a query that can be used to restrict the super set of documents that can be returned, without influencing score.

ISolrOperations<Product> solr = ...
var products = solr.Query(SolrQuery.All, new QueryOptions {
        FilterQueries = new ISolrQuery[] {
                new SolrQueryByField("manu", "apache"),
                new SolrQueryByRange<decimal>("price", 100m, 200m),
        }
});

More information in the Solr wiki.

Fields

By default Solr returns all stored fields. You can retrieve only selected fields instead:

ISolrOperations<Product> solr = ...
var products = solr.Query(SolrQuery.All, new QueryOptions {
        Fields = new[] {"id", "manu"}
});

Sorting

By default Solr returns search results ordered by "score desc". You can sort the results by any field(s):

ISolrOperations<Product> solr = ...
var products = solr.Query(SolrQuery.All, new QueryOptions {
        OrderBy = new[] {new SortOrder("manu", Order.DESC), SortOrder.Parse("id asc")}
});

You can random sort using RandomSortOrder:

solr.Query(SolrQuery.All, new QueryOptions {
        OrderBy = new[] {new RandomSortOrder("randomF")},
});

where randomF is a random sort field. RandomSortOrder has various constructors to generate a random seed (as in the example above) or use a predefined seed.

Pagination

In Solr you can't retrieve all your documents in single query. However, by default SolrNet will try to retrieve a large amount of documents, trying to mimic the behavior of a RDBMS without a TOP clause. It's not recommended to rely on this behavior. Instead, always define pagination parameters, for example:

ISolrOperations<Product> solr = ...
solr.Query("somequery", new QueryOptions{
  StartOrCursor = new StartOrCursor.Start(10),
  Rows = 25
});

This will fetch at most 25 documents, starting from the 10th document in the total result set.

If you're planning to paginate beyond the first few pages of results, take a look at CursorMark instead.

Additional parameters

Solr has lots of features that aren't directly mapped in SolrNet, but you can enable and use most of them with the ExtraParams dictionary. Parameters defined in ExtraParams are directly passed to the Solr querystring. For example you can restrict the maximum time allowed for a query:

ISolrOperations<Product> solr = ...
var products = solr.Query(SolrQuery.All, new QueryOptions {
        ExtraParams = new Dictionary<string, string> {
                {"timeAllowed", "100"}
        }
});

Or enable DisMax instead of the standard request handler:

ISolrOperations<Product> solr = ...
var products = solr.Query(SolrQuery.All, new QueryOptions {
        ExtraParams = new Dictionary<string, string> {
                {"qt", "dismax"}
        }
});

LocalParams

LocalParams provide a way to add certain metadata to a piece of query. It's used among other things to change the default operator type on the fly for a particular query.

In SolrNet, LocalParams are represented by the LocalParams class, which is basically a Dictionary<string, string>. LocalParams are attached to a query using the "+" operator. Here's an example:

solr.Query(new LocalParams {{"type", "dismax"},{"qf", "myfield"}} + new SolrQuery("solr rocks"));

This will generate: q={!type=dismax qf=myfield}solr rocks

More information about LocalParams in the Solr wiki.

ExtraParams

ExtraParams provides a way to add extra arbitrary parameters in the request query string.

Differently from LocalParams which is an IDictionary, ExtraParams is an IEnumerable<KeyValuePair<string, string>> therefore it does not have an issue with repeated keys. A sample scenario could be that you want to apply multiple boost queries (bq).

Please look at the example below:

var extraParams = new List<KeyValuePair<string, string>>();

extraParams.Add(new KeyValuePair<string, string>("bq", "SomeQuery^10"));
extraParams.Add(new KeyValuePair<string, string>("bq", "SomeOtherQuery^10"));

var options new new QueryOptions();
options.ExtraParams = extraParams; //Since my List implements the right interface

solr.Query(myQuery, options)