Azure Search: Using Azure Search (part 2 of 3)

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Date posted
7 February 2019
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15 Minutes
James Taylor

Azure Search: Using Azure Search (part 2 of 3)

/></figure> </div> <p>This post picks up where my previous post '<a href=Introducing Azure Search' left off.

In this section I will describe the basics of how to use Azure Search through the REST API.

Creating an Index

/></figure> <p>In the Indexes section of this document an example index is provided. This index can be used as a body to the REST call above. Other index tasks that can be performed through the REST API include updating an index, deleting an index, listing the indexes in a search service, getting index stats and analysing text through an index. More information about the different index operations can be found here <a href=https://docs.microsoft.com/en-us/rest/api/searchservice/index-operations.

Analysing Text

/></figure> <p>After creating an index, you may want to test how text is analysed by the index, especially if you have used custom analysers or tokenisers. The REST call above can be made to show how text will be analysed. An example body is shown below:</p> <figure ><img src=https://docs.microsoft.com/en-us/rest/api/searchservice/test-analyzer

Adding/Updating/Deleting Documents

/></figure> <p>The content of the above request should match the following form:</p> <figure ><img src=https://docs.microsoft.com/en-us/rest/api/searchservice/document-operations including advanced operations such as enabling autocomplete and suggestions.

Searching/Filtering

Within Azure Search there are 3 possible ways to search. Lucene querying allows all search capabilities of Azure Search, but simple querying excludes fuzzy and other advanced search options. OData expressions are available such as filtering and ordering of search results. Lucene or simple querying can be used in conjunction with OData expressions.

Searching using the REST API can be done via a GET request:

/></figure> <p>Or a post request:</p> <figure ><img src=https://docs.microsoft.com/en-us/azure/search/search-explorer.

Simple Query

Simple querying is the default option when using Azure Search, but to set this value manually you must set "queryType=simple" in the request as a query parameter. Simple queries support 'And', 'Or' and 'Not' expressions. More information can be found here https://docs.microsoft.com/en-us/rest/api/searchservice/simple-query-syntax-in-azure-search.

Lucene Query

For more complicated searches consider using Lucene search terms. This can be done by setting "queryType=full" as a query parameter in the request. Examples of more complicated searches are wildcard, proximity, regular expressions and fuzzy searching. More information can be found here https://docs.microsoft.com/en-us/rest/api/searchservice/lucene-query-syntax-in-azure-search.

OData Query

OData operations can be specified alongside simple or Lucene searching. These include filtering, geographical operations and comparison operations. More information can be found here https://docs.microsoft.com/en-us/rest/api/searchservice/odata-expression-syntax-for-azure-search.

Creating an Indexer and Data Source

First create a data source to be used by the indexer when syncing data.

/></figure> <p>A PUT request can also be used to update a data source (if the specified data source does not exist then it will be created). The request body must be in the following format:</p> <figure ><img src=https://docs.microsoft.com/en-us/rest/api/searchservice/indexer-operations.

Other Operations

There are lots of operations that can be performed through the REST API. Below I will briefly describe some of these additional operations.

Document Operations

Azure Search can provide suggestions based on the user's search terms. The field being searched is specified, for example if the user is searching using "Bri" for a field representing a city then suggestions will return "Brighton", "Bristol" and "Brisbane". This functionality can be used as a search-as-you-type style search.

Another document operation provided by Azure Search is auto complete. This is similar to suggestions but returns values that are currently in the index.

Suggestions and autocomplete are more advanced features but other simple features such as document counting and single document lookup can be done through the REST API. Information about all document operations can be found here https://docs.microsoft.com/en-us/rest/api/searchservice/document-operations.

Skillsets

Skillsets provide advanced natural language processing via cognitive AI skills. These skills can be built-in skills, custom skills or a combination of both. Skillsets are defined in the indexer and are used when the indexer is run. Information on defining a skillset, including an example can be found here https://docs.microsoft.com/en-gb/azure/search/cognitive-search-defining-skillset as well as information about how to create a skillset https://docs.microsoft.com/en-us/rest/api/searchservice/create-skillset.

Synonyms

Synonyms can be used to create custom rules to rewrite a search query. These operations are often used when mappings between certain search terms are known by the developer. For example if an index holds information about houses and one of the fields is a description of the house, a synonym mapping could be created between the words 'large', 'spacious' and 'roomy'. When a user searches by any of these terms then matches will occur between all of the words. More information about creating and managing synonym maps can be found here https://docs.microsoft.com/en-us/rest/api/searchservice/synonym-map-operations.

SDK and Azure portal

Azure provide an SDK for .NET development as well as tutorials in how to use the REST API with Node.js and Java. These tutorials can be found using the below links https://docs.microsoft.com/en-us/azure/search/search-get-started-java, https://docs.microsoft.com/en-us/azure/search/search-get-started-nodejs, https://docs.microsoft.com/en-us/azure/search/search-howto-dotnet-sdk.

Throughout this section I have described how to use the REST API. As well as the REST API and the SDK, the Azure portal can be used. Performing most of the operations described can be done through the portal. It is often just as easy to use the REST API, and since this is how it will be used in development it is a good idea to use the API. However, it is possible to use the portal for most operations and can be the easiest way to get up and running quickly.

Next up I will describe deployment, local development and conclusion in my final blog.

About the author

James Taylor