IJSValueReader-api-windows.md

id	title
IJSValueReader	IJSValueReader

Kind: interface

Forward-only reader for JSON-like streams. It is used to read data sent between native modules and the Microsoft.ReactNative library.

The JSON-like streams are data structures that satisfy the JSON specification. The data structure may have objects with name-value pairs and arrays of items. Property values or array items can be of type Null, Object, Array, String, Boolean, or Number. The IJSValueReader treats the Number type as Int64 or Double. See JSValueType.

When IJSValueReader reads data it must walk the whole tree without skipping any items. For example, if the current value type is Object, one must call GetNextObjectProperty to start reading the current object's properties, and if the current type is Array, GetNextArrayItem must be called to start reading the elements in the array. These functions must be called in a loop until they return false, which signifies that there are no more items within the object or array being traversed.

See the IJSValueWriter for the corresponding writer interface.

The IJSValueReader and IJSValueWriter must be rarely used directly. Use them to create functions that serialize a native type or deserialize into a native type. The rest of application code must use these functions to serialize/deserialize values. The Microsoft.ReactNative.Cxx and Microsoft.ReactNative.Managed projects offer serializer/deserializer functions for many standard types. Use them directly or to define serializer/deserializer functions for your types.

Properties

ValueType

readonly JSValueType ValueType

Gets the type of the current value.

Methods

GetBoolean

bool GetBoolean()

Gets the current Boolean value.

GetDouble

double GetDouble()

Gets the current Number value as a Double.

GetInt64

int64_t GetInt64()

Gets the current Number value as an Int64.

GetNextArrayItem

bool GetNextArrayItem()

Advances the iterator within the current array to fetch the next array element. The element can then be obtained by calling one of the Get functions.

Returns true if the next array item is acquired successfully. Otherwise, it returns false, meaning that reading of the JSON-like array is completed.

Note

• Use ValueType to get the type of the array item and other GetXXX methods to read it.
• Use GetNextObjectProperty method to start reading property value of type JSValueType Object.
• Use GetNextArrayItem method to start reading property value of type JSValueType `Array

GetNextObjectProperty

bool GetNextObjectProperty(out string propertyName)

Advances the iterator within the current object to fetch the next object property. The property value can then be obtained by calling one of the Get functions.

Returns true if the next property is acquired successfully. In that case the propertyName is set to the name of the property. Otherwise, it returns false, meaning that reading of the JSON-like object is completed.

Note

• Use ValueType to get the type of the property value and other GetXXX methods to read it.
• Use GetNextObjectProperty method to start reading property value of type JSValueType Object.
• Use GetNextArrayItem method to start reading property value of type JSValueType `Array

GetString

string GetString()

Gets the current String value.

Referenced by

• IRedBoxErrorInfo
• IViewManagerCreateWithProperties
• IViewManagerWithCommands
• IViewManagerWithNativeProperties
• MethodDelegate
• SyncMethodDelegate