-->Inheritance
- Java Pair Object
- For Each Key In Object
- Generate Key Value Pairs In An Objective
- Generate Key Value Pairs In An Object Formula
- Generate Key Value Pairs In An Object Worksheet
Nov 16, 2018 3. Key-value pair Generation in MapReduce. Let us now learn how key-value pair is generated in Hadoop MapReduce?In MapReduce process, before passing the data to the mapper, data should be first converted into key-value pairs as mapper only understands key-value pairs of data. We will begin this tip introducing key-value pairs by using simple C# for demonstrative purposes - the following code is not meant to be run inside a class or method for an object in production - this is only to show a key-value dictionary in C#. Jul 18, 2018 In MySQL, you can use the JSONOBJECT function to create a JSON object from a list of key/value pairs. You provide each key/value pair as two separate arguments. Each pair becomes a key/value pair in the resulting JSON object. You must provide an even number of arguments (otherwise, you’d have an incomplete pair somewhere in your list of arguments). The function also accepts an. Define key value pair employee object and push it into employees array. In below example we have employee keys say id, name and age with their respective values. To verify it just iterate the employee array and retrieve the each employee value with the help of keys. VB.NET KeyValuePair Examples Use KeyValuePair, which has two member fields. Access the Key and Value properties. ' Create List of key-value pairs. KeyValuePair stores a key and a value together in a single object in memory. It is a value type. This makes it more efficient in.
Definition
Defines a key/value pair that can be set or retrieved.
Type Parameters
- TValue
The type of the value.
KeyValuePair<TKey,TValue>
- Attributes
Examples
The following code example shows how to enumerate the keys and values in a dictionary, using the KeyValuePair<TKey,TValue> structure.
This code is part of a larger example provided for the Dictionary<TKey,TValue> class.
Remarks
The Dictionary<TKey,TValue>.Enumerator.Current property returns an instance of this type.
The
foreach
statement of the C# language (for each
in C++, For Each
in Visual Basic) returns an object of the type of the elements in the collection. Since each element of a collection based on IDictionary<TKey,TValue> is a key/value pair, the element type is not the type of the key or the type of the value. Instead, the element type is KeyValuePair<TKey,TValue>. For example:Java Pair Object
The
foreach
statement is a wrapper around the enumerator, which allows only reading from, not writing to, the collection.Constructors
KeyValuePair<TKey,TValue>(TKey, TValue) | Initializes a new instance of the KeyValuePair<TKey,TValue> structure with the specified key and value. |
Properties
Key | Gets the key in the key/value pair. |
Value | Gets the value in the key/value pair. |
Methods
Deconstruct(TKey, TValue) | |
ToString() | Returns a string representation of the KeyValuePair<TKey,TValue>, using the string representations of the key and value. |
Applies to
See also
- TypeScript Tutorial
- TypeScript Useful Resources
- Selected Reading
An object is an instance which contains set of key value pairs. The values can be scalar values or functions or even array of other objects. The syntax is given below −
Syntax
As shown above, an object can contain scalar values, functions and structures like arrays and tuples.
Example: Object Literal Notation
On compiling, it will generate the same code in JavaScript.
For Each Key In Object
The output of the above code is as follows −
TypeScript Type Template
Let’s say you created an object literal in JavaScript as −
In case you want to add some value to an object, JavaScript allows you to make the necessary modification. Suppose we need to add a function to the person object later this is the way you can do this.
If you use the same code in Typescript the compiler gives an error. This is because in Typescript, concrete objects should have a type template. Objects in Typescript must be an instance of a particular type.
You can solve this by using a method template in declaration.
Example: Typescript Type template
On compiling, it will generate the same code in JavaScript.
The output of the above code is as follows −
Objects can also be passed as parameters to function.
Example: Objects as function parameters
The example declares an object literal. The function expression is invoked passing person object.
On compiling, it will generate following JavaScript code.
Its output is as follows −
You can create and pass an anonymous object on the fly.
Example: Anonymous Object
On compiling, it will generate following JavaScript code.
Its output is as follows −
Duck-typing
Generate Key Value Pairs In An Objective
In duck-typing, two objects are considered to be of the same type if both share the same set of properties. Duck-typing verifies the presence of certain properties in the objects, rather than their actual type, to check their suitability. The concept is generally explained by the following phrase −
“When I see a bird that walks like a duck and swims like a duck and quacks like a duck, I call that bird a duck.”
Generate Key Value Pairs In An Object Formula
The TypeScript compiler implements the duck-typing system that allows object creation on the fly while keeping type safety. The following example shows how we can pass objects that don’t explicitly implement an interface but contain all of the required members to a function.