How to Highlighting Search Results Using Apache SOLR with PHP code

Question

I developed search page using SOLR with Tomcat servlet container. Using PHP code I post the search query into solrQuery() function and In this function have defined query parameter as follows.

$query = "?q=".trim(urlencode($q)) &version=2.2&start=0&rows=10&indent=on&hl=true&hl.fl=title";

I have passed highlighted "hl=true&hl.fl=title" parameters. I dont know about How to parse/display highlighted results in my search page?

can any one help me?

Answer 1

The way highlighting works in Solr is the following:

At the beggining of the XML response with the results, you see a "result" node with child "doc" nodes which contain your search results. Something like this:

 <doc>
  <str name="body">Merge transfer will merge one item with another. The new item can be either from same location or from different location. Merge transfer directions:  Open your Paper Tiger Online and select the database. Select item(s) you want to merge except for the one you want to merge the items into, click on Transfer and select Merge. A pop up will be opened asking New Location, once you select the location, the items in the location will be loaded in to the “File to Merge”.  Select a file in the “File to Merge” list. Choose whether you want to be reminded to move this file or not  Click Merge File  Add any additional keywords, notes, action date, change category (if necessary)  Click Merge Item button  If you chose to be reminded, you'll need to click the Confirm box to confirm the merge, then the merge will happen. (You can also cancel the merge from the Confirm page) </str>
  <str name="current-tags"/>
  <str name="id">141156</str>
  <str name="title">What is a merge transfer? How do I merge files?</str>
 </doc>

At the end of the XML response with the resutls, you will see a "lst" node with the name "highlighting". You will notice that within each node, you'll see a child "lst" node with the name of the unique identifier that you've chosen for your document. Something like this:

<lst name="141154">
  <arr name="body">
    <str>Transfers are used to move or &lt;em&gt;merge&lt;/em&gt; the items from one location and another location and creating duplicates items in the locations. You might want to move and item from Action to Reference or Archive to an off-site location. You would want to move the item in Paper Tiger to ensure you can find it</str>
  </arr>
</lst>

The easiest way for me to do it is just to traverse the "results" node first and set my variables to the content of the search results as such. Then, within the loop to display each item, I loop through the "highlighted" node and search for the item's ID to see if I find a match. If a match is found, I will overwrite the content of the original variables with highlighted content.

This way, you will display results wether there is a highlighted match found or not.

    cURL_address($curl_url);

$xml = new SimpleXMLElement($data);

    foreach ($xml->children() as $node) {

        $arr = $node->attributes();   // returns an array
        $no_results = FALSE;

        //When no results are found

        if ($arr["name"] == "response" && $arr["numFound"] == 0) {

            echo "No results found for '". $query ."'";
            $no_results = TRUE;

        }

        if ($arr["name"] == "response") {

            if ($no_results != TRUE) {
                echo "<h4 id=\"search_results\">Search results for '".$query."'</h4>";
            } 

            foreach ($node->doc as $response) {

                //Initially set all the variables to the non-highlighted content

                $entry_title = $response->str[3];
                $entry_body = substr($response->str[0], 0, 300)."&#8230;";
                $entry_id = $response->str[2];
                $entry_tags = $response->str[1];

                //logic to see if we need to add ellipsis to start/end of body
                $orig_body_beggining = substr($response->str[0], 0, 10);
                $orig_body_end = substr($response->str[0], -10);

                //Now loop through every highlighted field to see if we have a node that matches the original item's ID

                foreach ($xml->lst[1]->lst as $hl_data) {

                    $arr2 = $hl_data->attributes();   // returns an array

                    $hl_arr = $arr2["name"];

                    if ((string)$entry_id == (string)$hl_arr) {

                        foreach ($hl_data->arr as $hl_content) {

                            $arr3 = $hl_content->attributes();

                            //Use a switch to overwrite existing variables if a new one exists that is highlighted

                            switch($arr3['name']) { // Get attributes as element indices
                                case 'body':
                                    $f_ellip = NULL;
                                    $l_ellip = NULL;
                                    if ($orig_body_beggining != substr((string)$hl_content->str, 0, 10)) {
                                        $f_ellip = "&#8230; ";
                                    }
                                    if ($orig_body_end != substr((string)$hl_content->str, 0, -10)) {
                                        $l_ellip = " &#8230;";
                                    }
                                    $entry_body = $f_ellip.(string)$hl_content->str.$l_ellip;
                                    break;
                                case 'title':
                                    $entry_title = (string)$hl_content->str;
                                    break;
                                case 'current-tags':
                                    $entry_tags = (string)$hl_content->str;
                                    break;
                                }

                        }

                    }
                }

Let me know what you think!