TwinCollection Class

Package:

com.microsoft.azure.sdk.iot.provisioning.service.configs

• java.lang.Object
• • java.util.HashMap<String, Object>
  • • com.microsoft.azure.sdk.iot.provisioning.service.configs.TwinCollection

public class TwinCollection extends Serializable

Representation of a single Twin collection for Provisioning.

The TwinCollection is an extension of aHashMap  ofString  and Object  that contain individual and general versioning mechanism.

By the Twin definition, theObject  can contain types ofBoolean  , Number  ,String  ,Object  , or a sub-TwinCollection, but it cannot be types defined by the user or arrays.

A TwinCollection can contain up to 5 levels of sub TwinCollections. Once the TwinCollection is a extension of theHashMap  , both TwinCollection as well as its sub-TwinCollections can be casted to Map of String and Object.

The collection will be represented in the rest API as a JSON in the body. It can or cannot contain the metadata (identified by the $ character at the beginning of the key.

Because of the Twin metadata, the character $ is not allowed in the entry key.

For instance, the following JSON is a valid TwinCollection with its metadata.

{
        "Color":"White",
        "MaxSpeed":{
            "Value":500,
            "NewValue":300
        },
        "$metadata":{
            "$lastUpdated":"2017-09-21T02:07:44.238Z",
            "$lastUpdatedVersion":4,
            "Color":{
                "$lastUpdated":"2017-09-21T02:07:44.238Z",
                "$lastUpdatedVersion":4,
            },
            "MaxSpeed":{
                "$lastUpdated":"2017-09-21T02:07:44.238Z",
                "$lastUpdatedVersion":4,
                "Value":{
                    "$lastUpdated":"2017-09-21T02:07:44.238Z",
                    "$lastUpdatedVersion":4
                },
                "NewValue":{
                    "$lastUpdated":"2017-09-21T02:07:44.238Z",
                    "$lastUpdatedVersion":4
                }
            }
        },
        "$version":4
    }
    

This class exposes the Twin collection with or without metadata as a Map here user can gat both the value and the metadata. For instance, in the above TwinCollection, get(Object) for Color will return White and getTwinMetadata(String) for Color will return the Object TwinMetadata and TwinMetadata.getLastUpdated() that will returns theDate  2017-09-21T02:07:44.238Z and TwinMetadata.getLastUpdatedVersion() that will returns theInteger  4.

For the nested TwinCollection, you can do the same, for instance, the following code will return the value and metadata of the NewValue nested in MaxSpeed:

// Get the value of the MaxSpeed, which is a inner TwinCollection.
    TwinCollection innerMaxSpeed = (TwinCollection) twinCollection.get("MaxSpeed");
    
    // From the inner TwinCollection, get the value of the NewValue.
    Long maxSpeedNewValue = innerMaxSpeed.get("NewValue");
    
    // As in the root TwinCollection, the inner TwinCollection contain its own metadata.
    // So, get the metadata information for the inner NewValue.
    TwinMetadata maxSpeedNewValueMetadata = innerMaxSpeed.getTwinMetadata("NewValue");
    Date newValueLastUpdated = maxSpeedNewValueMetadata.getLastUpdated(); //Shall contain `2017-09-21T02:07:44.238Z`
    Integer newValueLastUpdatedVersion = maxSpeedNewValueMetadata.getLastUpdatedVersion(); //Shall contain `4`
    

Constructor Summary

Constructor	Description
TwinCollection()	Constructor Creates an empty collection. Fill it with put(String key, Object value) or putAll(Map).
TwinCollection(Map<? extends String, Object> map)	Constructor Creates a new Twin collection coping the provided Map. Once TwinCollection extends Map, this method can copy another TwinCollection.

Method Summary

Modifier and Type	Method and Description
TwinMetadata	getTwinMetadata() Getter for the TwinCollection metadata
TwinMetadata	getTwinMetadata(String key) Getter for the entry metadata in the TwinCollection.
Integer	getVersion() Getter for the version.
Object	put(String key, Object value) Add a single new entry in the TwinCollection. OverrideHashMap.put(String, Object)  </code> .</p> This function will add a single pair key value to the TwinCollection. By the Twin definition, theObject  </code> can contain types of<code>Boolean  </code> , <code>Number  </code> ,<code>String  </code> ,<code>Object  </code> , or up to 5 levels of sub-TwinCollection, but it cannot be types defined by the user or arrays.</p>
void	putAll(Map<? extends String, ?> map) Add all information in the provided Map to the TwinCollection. OverrideHashMap.putAll(Map)  </code> .</p> This function will add all entries in the Map to the TwinCollection. If the provided key already exists, it will replace the value by the new one. This function will not delete or change the content of the other keys in the Map. As defined by the Twin, the value of a entry can be an inner Map. TwinCollection will accept up to 5 levels of inner Maps.
JsonElement	toJsonElement() Serializer Creates aJsonElement  </code> , which the content represents the information in this class and its subclasses in a JSON format.</p> This is useful if the caller will integrate this JSON with JSON from other classes to generate a consolidated JSON.

Inherited Members

Serializable.toJson() Serializable.toString()

Constructor Details

TwinCollection

public TwinCollection()

Constructor

Creates an empty collection. Fill it with put(String key, Object value) or putAll(Map).

TwinCollection

public TwinCollection(Map map)

Constructor

Creates a new Twin collection coping the provided Map. Once TwinCollection extends Map, this method can copy another TwinCollection.

Parameters:

map -

the Map of? extends String 

</code> and<code>Object 

</code> with the Twin collection </p>

Method Details

getTwinMetadata

public TwinMetadata getTwinMetadata()

Getter for the TwinCollection metadata

Returns:

the TwinMetadata of the Whole TwinCollection. It can benull 

</code> . </p>

getTwinMetadata

public TwinMetadata getTwinMetadata(String key)

Getter for the entry metadata in the TwinCollection.

Parameters:

key -

theString 

</code> with the name of the entry to retrieve the metadata. </p>

Returns:

the TwinMetadata ot the specific entry in the TwinCollection. It can benull 

</code> . </p>

getVersion

public Integer getVersion()

Getter for the version.

Returns:

TheInteger 

</code> with the version content. It can be<code>null 

</code> . </p>

put

public Object put(String key, Object value)

Add a single new entry in the TwinCollection.

OverrideHashMap.put(String, Object) 

</code> .</p>

This function will add a single pair key value to the TwinCollection. By the Twin definition, theObject 

</code> can contain types of<code>Boolean 

</code> , <code>Number 

</code> ,<code>String 

</code> ,<code>Object 

</code> , or up to 5 levels of sub-TwinCollection, but it cannot be types defined by the user or arrays.</p>

Parameters:

key -

theString 

</code> that represent the key of the new entry. It cannot be {code null} or empty. </p>

value -

theObject 

</code> that represents the value of the new entry. It cannot be user defined type or array. </p>

Returns:

TheObject 

</code> that correspond to the last value of this key. It will be<code>null 

</code> if there is no previous value. </p>

putAll

public void putAll(Map map)

Add all information in the provided Map to the TwinCollection.

OverrideHashMap.putAll(Map) 

</code> .</p>

This function will add all entries in the Map to the TwinCollection. If the provided key already exists, it will replace the value by the new one. This function will not delete or change the content of the other keys in the Map.

As defined by the Twin, the value of a entry can be an inner Map. TwinCollection will accept up to 5 levels of inner Maps.

Parameters:

map -

AMap 

</code> of entries to add to the TwinCollection. </p>

toJsonElement

public JsonElement toJsonElement()

Serializer

Creates aJsonElement 

</code> , which the content represents the information in this class and its subclasses in a JSON format.</p>

This is useful if the caller will integrate this JSON with JSON from other classes to generate a consolidated JSON.

Returns:

TheJsonElement 

</code> with the content of this class. </p>