Search
The Search operation is used to retrieve a resources from the server using search parameters. This will be an overview of what we support from the FHIR search specification. The server will return the resources that match the search parameters.
Resource Parameters supported
| Type | Supported | Description |
|---|---|---|
| Number | Yes | Searching on a simple numerical value in a resource |
| Date/DateTime | Yes | A date parameter searches on a date/time or period |
| String | Yes | Searching on simple string values in a resource |
| Token | Yes | A token type is a parameter that provides a close to exact match search on a string of characters. |
| Reference | Yes | A reference parameter refers to references between resources. |
| Composite | No | Composite search parameters support joining single values with a $ |
| Quantity | Yes | A quantity parameter searches on the Quantity data type. |
| URI | Yes | The uri parameter refers to an element that contains a URI |
Special Parameters
| Name | Supported | Description |
|---|---|---|
| _id | Yes | Logical id of a resource |
| _lastUpdated | Yes | Instant the resource was last updated |
| _tag | Yes | Meta.tag of the resource |
| _profile | Yes | Meta.profile of the resource |
| _security | Yes | Meta.security of the resource |
| _text | Yes | Search on the narrative of the resource |
| _content | Yes | Search on the content of the resource |
| _list | No | |
| _has | No | For reverse chaining |
| _type | Yes | Filter system search on a specific set of resource types. |
| _sort | Yes | Set the parameter to use for sorting. We also support sorting priority based on comma seperation of parameters. |
| _count | Yes | Max it can be set to is 50. |
| _include | yes | Include related resources in bundle. Include resources referenced by current resource. |
| _revinclude | yes | Include related resources in Bundle. Include resources that reference current resource. |
| _summary | No | Return a portion of the resource |
| _total | Yes | Return the total count of parameters matching query (including resources not returned by _count limitation). |
| _element | No | Return summary based on parameters |
| _countained | No | Whether to return resources contained in other resources. |
| _containedType | No | Determine whether to return container or contained. |
Chaining
When searching for data you may want to find resources based on data linked to a resource. For example finding an Observation by a patients MRN identifier. To perform these kinds of searches you use chaining. Our api supports chained parameters so in the example above you can perform the following query:
- CLI
curl --request GET --url https://{my-api}/Observation?patient.identifier={mrn-system}|12345
To retrieve all observations for a patient with an mrn identifier of 12345. The way this is accomplised is that Observation stores a reference parameter for patient and the Patient resource has a token parameter for identifier so in above example we chain both of these parameters together. You can have chaining to any depth.
Modifiers
Modifiers are colon seperated values that alter the behavior of search.
For example the following query:
- CLI
curl --request GET --url https://{my-api}/Patient?name=bob
Will perform a default string search which is a case insensitive search for all patients whose name starts with bob.
To make this more specific we can use the exact modifier as follows:
- CLI
curl --request GET --url https://{my-api}/Patient?name:exact=Bob
This will perform a case sensitive search to find all Patients whose name exactly matches Bob.
Supported Modifiers
| Name | Supported | Types | Description |
|---|---|---|---|
| missing | Yes | token | Search for values that don't have a value for given parameter. |
| exact | Yes | string | Search for an exact match of the given value. |
| contains | Yes | string | Search for a value that contains given value. |
Prefixes
Prefix which specifies the type of matching that occurs. This is used for odered parameter types number, date and quantity.
Currently we only have support for number based prefixes but plan on adding date and quantity support in the near future.
For example the following query:
- CLI
curl --request GET --url https://{my-api}/RiskAssessment?probability=0.5
Will query for all RiskAssessments who a probability of 0.5 with range given by decimal precision of query.
If instead you want to query for RiskAssessments with probability less than equal to 0.5 you would use the le prefix as follows:
- CLI
curl --request GET --url https://{my-api}/RiskAssessment?probability=le0.5
Supported Prefixes
| Name | Supported | Type | Description |
|---|---|---|---|
| eq | Yes | number | exact match of a value. By default matching is done by range of decimal precision this forces an exact match. |
| ne | Yes | number | Search for value of parameter that is not the value provided. |
| gt | Yes | number | Search for values greater than value provided. |
| lt | Yes | number | Search for values less than value provided. |
| ge | Yes | number | Search for values greater than or equal to the value provided. |
| le | Yes | number | Search for values less than or equal to the value provided. |
| sa | No | the value for the parameter in the resource starts after the provided value | |
| eb | No | the value for the parameter in the resource ends before the provided value | |
| ap | No | The value for the parameter in the resource is approximately the same to the provided value. |