Querying Solr using the HTTP API

Querying multi value fields

Here, I have a multi value field author:

<field
  name="author"
  type="string"
  indexed="false"
  stored="true"
  multiValued="true" />

To query for documents with a given author, you cannot (for some reason I don't understand) use a reqular q=author:John, instead you must a query filter fq:

fq=(author:0+OR+John)

The URL then looks like this, example here given with curl:

$ curl 'http://search:8983/core1/select?q=*:*&fq=(author:0+OR+John)&wt=json&indent=true

If you want to apply more parameters to the search to narrow down the results, you can include the regular single valued fields in the q parameter as normal. For example, here I want to include only the documents that have the contenttype field set to story:

$ curl 'http://search:8983/core1/select?q=contenttype:story&fq=(author:0+OR+John)&wt=json&indent=true

An in case you were wondering, yes you need the first 0+OR, or else it doesn't work 😉

Creating one facet per day

Say you have a date time field called creationdate, and you would like to search for all documents containing the string moore and you want facets showing how many documents were created per day.

The intuitive way of doing this would be to ask Solr to facet on the field: ?facet.field=creationdate, however, this would give you one facet per second, which is not what you want:

$ curl 'http://search.example.com/solr/editorial/select?q=moore&wt=json&facet=true&facet.field=creationdate' | \
  jq .facet_counts
{
  "facet_queries": {},
  "facet_fields": {
    "creationdate": [
      "2018-12-24T12:42:49Z",
      1,
      "2018-12-24T12:47:52Z",
      1,
      "2019-01-02T15:16:28Z",
      1,
      "2018-11-29T15:37:46Z",
      0,
      "2018-11-29T15:37:47Z",
      0
    ]
  },
  "facet_ranges": {},
  "facet_intervals": {},
  "facet_heatmaps": {}
}

Instead, you must utilise the facet range mechanism, the following fields gives you facets per day (we ignore days with no articles, facet.mincount=1):

facet=true&
facet.range=creationdate&
facet.mincount=1&
f.creationdate.facet.range.start=2017-12-24T00:42:49Z&
f.creationdate.facet.range.end=2028-12-24T12:42:49Z&
f.creationdate.facet.range.gap=%2B1DAY

With this in place, we get one facet per day, showing how many articles were written:

$ curl 'http://search.example.com/solr/editorial/select?q=moore&wt=json&facet=true&facet.range=creationdate&f.creationdate.facet.range.start=2017-12-24T00:42:49Z&f.creationdate.facet.range.end=2028-12-24T12:42:49Z&f.creationdate.facet.range.gap=%2B1DAY&facet.mincount=1' | \
jq .facet_counts
{
  "facet_queries": {},
  "facet_fields": {},
  "facet_ranges": {
    "creationdate": {
      "counts": [
        "2018-12-24T00:42:49Z",
        2,
        "2019-01-02T00:42:49Z",
        1
      ],
      "gap": "+1DAY",
      "start": "2017-12-24T00:42:49Z",
      "end": "2028-12-25T00:42:49Z"
    }
  },
  "facet_intervals": {},
  "facet_heatmaps": {}
}

You probably want to adjust the .start and .end values, but this should be enough to get you started.

Happy searching!