Micro build low code tutorial - variable definition

Catalog

01 General introduction

02 Application Introduction

03 Page introduction

04 hello,world

In the previous section, we showed how to write the first line of code in low code , In this section, we officially enter our programming teaching .

To be a programmer , The first is to learn grammar . Just like when we learn to speak , We start with words and phrases , Then organize the words into sentences , Slowly we will learn the language .

As a machine, it also has its own language , Machine language only knows 0 and 1, In order to facilitate human control of machines , The inventor of computer language made some abstraction , No matter what kind of language , There will probably be variables 、 loop 、 Branch 、 data type 、 Type conversion, etc . Of course, there are concepts such as objects in high-level languages .

As a beginner, Xiaobai , We also need to have a solid grasp of these basic concepts , Basic concepts learned , You won't be confused when learning the official template later .

This section focuses on the concept of variables . The so-called variable can be understood as a container , The box in daily life is a kind of container , We'll put the data in this box . Here's the picture ：

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We can use the following syntax to create a variable and give it a value

let message = "hello"

Low code uses javascript The grammar of , This variable definition is valid , But to make it easier to define variables , Low code provides a visual variable definition method .

Enter the low code console , Find the variable icon on the navigation bar

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The window of variable definition pops up , The scope of variables includes global and page level

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If the variable defined in the global , Every page can use , If the variable defined as page level can only be used in this page .

The method of variable definition is to move the mouse over the page name , Click next to + Number

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Identification of the input variable , Select the type of variable . There are three types , They are ordinary variables 、 Model variables and parameter variables .

Common variables are javascript Variables that can be defined , Type a string( character string )、number（ The number ）、boolean（ Boolean value ）、array（ Array ）、object（ object ）. Different types can store data with different structures .

Model variables correspond to data sources , You need to select a specific data source , Generally, you can choose to obtain a single or multiple records of the data source .

Parameter variables are generally used to receive parameters during page delivery , For example, in the details page, you need to obtain the record's primary key .

In order to be consistent with the above method of using code to define variables , Let's create a basic variable here message, Variable type selection string

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When defining variables, you can also set initial values , Let's give one here hello The initial value of the

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Click the save button , The variable we just defined appears at the bottom of the page

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