Mapping Object Attribute in SolrNet


Solr fields defined in your schema.xml must be mapped to properties in a .NET class. There are currently three built-in ways to map fields:

Attributes (default)

With this method you decorate the properties you want to map with the SolrField and SolrUniqueKey attributes. The attribute parameter indicates the corresponding Solr field name.


public class Product {
    public string Id { get; set; }

    public string Manufacturer { get; set; }

    [SolrField("cat")] // cat is a multiValued field
    public ICollection<string> Categories { get; set; }

    public decimal Price { get; set; }

    public bool InStock { get; set; }

    public DateTime Timestamp { get; set; }

    public double? Weight { get; set;} // nullable property, it might not be defined on all documents.

This way of mapping is implemented by the AttributesMappingManager class.

Index-time field boosting

You can also use the mapping attribute to apply a boost to a specific field at index-time.

[SolrField("inStock", Boost = 10.5)]
public bool InStock { get; set; }

.. this will add a boost of 10.5 to the InStock field each time the document is indexed.


This maps each property of the class to a field of the exact same name as the property (note that Solr field names are case-sensitive). It’s implemented by the AllPropertiesMappingManager class. Note that unique keys cannot be inferred, and therefore have to be explicitly mapped. The same mapping as above could be accomplished like this:

public class Product {
    public string id { get; set; }
    public string manu_exact { get; set; }
    public ICollection<string> cat { get; set; }
    public decimal price { get; set; }
    public bool inStock { get; set; }
    public DateTime timestamp { get; set; }
    public double? weight { get; set; }

Then to add the unique key:

var mapper = new AllPropertiesMappingManager();

Manual mapping

This allows you to programmatically define the field for each property:

public class Product {
    public string Id { get; set; }
    public string Manufacturer { get; set; }
    public ICollection<string> Categories { get; set; }
    public decimal Price { get; set; }
    public bool InStock { get; set; }
    public DateTime Timestamp { get; set; }
    public double? Weight { get; set; }
var mgr = new MappingManager();
var property = typeof (Product).GetProperty("Id");
mgr.Add(property, "id");
mgr.Add(typeof(Product).GetProperty("Manufacturer"), "manu_exact");
mgr.Add(typeof(Product).GetProperty("Categories"), "cat_exact");
mgr.Add(typeof(Product).GetProperty("Price"), "price");
mgr.Add(typeof(Product).GetProperty("InStock"), "inStock");
mgr.Add(typeof(Product).GetProperty("Timestamp"), "timestamp");
mgr.Add(typeof(Product).GetProperty("Weight"), "weight");

Dictionary mappings and dynamic fields

Solr dynamicFields can be mapped differently depending on the use case. They can be mapped “statically”, e.g, given:

<dynamicField name="price_*"  type="integer"  indexed="true"  stored="true"/>

a particular dynamicField instance can be mapped as:

public decimal? Price {get;set;}

However, it’s often necessary to have more flexibility. You can also map dynamicFields as a dictionary, with a field name prefix:

public IDictionary<string, decimal> Price {get;set;}

In this case, price_ is used as a prefix to the actual Solr field name, e.g. with this mapping, Price["regular"] maps to a Solr field named price_regular.

Another, even more flexible mapping:

public IDictionary<string, object> OtherFields {get;set;}

This acts as a catch-all container for any fields that are otherwise unmapped. E.g. OtherFields["price_i"] maps to a Solr field named price_i.

Fully loose mapping

An even more “dynamic” mapping can be achieved by using a Dictionary<string,object> as document type. In this document type, the dictionary key corresponds to the Solr field name and the value to the Solr field value. Statically typing the fields is obviously lost in this case, though.

When adding documents as Dictionary<string,object> SolrNet will recognize field value types as usual, e.g. you can use strings, int, collections, arrays, etc. Example:

Startup.Init<Dictionary<string, object>>(serverUrl);
var solr = ServiceLocator.Current.GetInstance<ISolrOperations<Dictionary<string, object>>>();
solr.Add(new Dictionary<string, object> {
  {"field1", 1},
  {"field2", "something else"},
  {"field3", new DateTime(2010, 5, 5, 12, 23, 34)},
  {"field4", new[] {1,2,3}},

When fetching documents as Dictionary<string,object> SolrNet will automatically map each field value to a .NET type, but it’s up to you to downcast the field value to a properly typed variable. Example:

ISolrOperations<Dictionary<string, object>> solr = ...
ICollection<Dictionary<string, object>> results = solr.Query(SolrQuery.All);
bool inStock = (bool) results[0]["inStock"];

Custom mapping

You can code your own mapping mechanism by implementing the IReadOnlyMappingManager interface.

To override the default mapping mechanism, see this page.


Copy from:

2 thoughts on “Mapping Object Attribute in SolrNet

  1. I have created a mapper:

    var mapper = new AllPropertiesMappingManager();

    how do I use this?
    Where to set this?

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s