Tutorial by Examples: field

extern crate serde; extern crate serde_json; #[macro_use] extern crate serde_derive; use std::collections::BTreeMap as Map; #[derive(Serialize)] struct Resource { // Always serialized. name: String, // Never serialized. #[serde(skip_serializing)] hash: String, ...

We use this model from the first example: class Person(models.Model): name = models.CharField(max_length=50) description = models.TextField() class Club(models.Model): name = models.CharField(max_length=50) members = models.ManyToManyField(Person) Add Tom and Bill to the N...

Pattern matching can be used to deconstruct records. We illustrate this with a record type representing locations in a text file, e.g. the source code of a program. type location = { filename : string; line: int; column: int; offset: int; } A value x of type location can be deconstr...

The following examples can be tested on https://ellie-app.com/m9vmQ8NcMc/0. import Html exposing (..) import Json.Decode payload = """ [ { "bark": true, "tag": "dog", "name": "Zap", "playful": true } , { "w...

Header fields (usually just called ‘headers’) may be added to an HTTP request to provide additional information with the request. A header has semantics similar to parameters passed to a method in any programming language that supports such things. A request with Host, User-Agent and Referer header...

CREATE TABLE table_name ( id INT NOT NULL AUTO_INCREMENT, json_col JSON, PRIMARY KEY(id) );

In case we want to use enum with more information and not just as constant values, and we want to be able to compare two enums. Consider the following example: public enum Coin { PENNY(1), NICKEL(5), DIME(10), QUARTER(25); private final int value; Coin(int value){ this....

As per the Mongoid Documentation, there are 16 valid field types: Array BigDecimal Boolean Date DateTime Float Hash Integer BSON::ObjectId BSON::Binary Range Regexp String Symbol Time TimeWithZone To add a field (let's call it name and have it be a String), add this to your mode...

Public Function GetUserFirstName(UserName As String) As String Dim Firstname As String = "" 'Specify the SQL that you want to use including a Parameter Dim SQL As String = "select firstname from users where username=@UserName" 'Provide a Data Sourc...

Used by awk to split each record into multiple fields: echo "a-b-c d-e-f" | awk 'BEGIN {FS="-"} {print $2}' will result in: b e The variable FS can also be set using the option -F: echo "a-b-c d-e-f" | awk -F '-' '{print $2}' By default, the fields are se...

This inserts a json dictionary where one of the members is an array of strings into the table that was created in another example. INSERT INTO myjson(dict) VALUES('{"opening":"Sicilian","variations":["pelikan","dragon","najdorf"]}'); ...

In the previous example we saw how mixed data types can be inserted into a JSON field. What if we want to update that field? We are going to add scheveningen to the array named variations in the previous example. UPDATE myjson SET dict=JSON_ARRAY_APPEND(dict,'$.variations','schevening...

#include <stdio.h> int main(void) { /* define a small bit-field that can hold values from 0 .. 7 */ struct { unsigned int uint3: 3; } small; /* extract the right 3 bits from a value */ unsigned int value = 255 - 2; /* Binary 11111101 */ small.u...

Setting a field to NULL works exactly like with any other value: UPDATE Employees SET ManagerId = NULL WHERE Id = 4

For example inserting an employee with no phone number and no manager into the Employees example table: INSERT INTO Employees (Id, FName, LName, PhoneNumber, ManagerId, DepartmentId, Salary, HireDate) VALUES (5, 'Jane', 'Doe', NULL, NULL, 2, 800, '2016-07-22') ;

Used by awk to separate fields output by the print statement. For example: echo "a b c d e f" | awk 'BEGIN {OFS="-"} {print $2, $3}' produces: b-c e-f The default value is , a string consisting of a single space.

You can use the DataExtension mechanism to add extra database fields to an existing DataObject: class MyMemberExtension extends DataExtension { private static $db = [ 'HairColour' => 'Varchar' ]; } And apply the extension: # File: mysite/_config/app.yml Member: exten...

The variable FS is used to set the input field separator. In awk, space and tab act as default field separators. The corresponding field value can be accessed through $1, $2, $3... and so on. awk -F'=' '{print $1}' file -F - command-line option for setting input field separator. awk 'BEGIN ...

This variable is used to set the output field separator which is a space by default. awk -F'=' 'BEGIN { OFS=":" } { print $1 }' file Example: $ cat file.csv col1,col2,col3,col4 col1,col2,col3 col1,col2 col1 col1,col2,col3,col4,col5 $ awk -F',' 'BEGIN { OFS="|" } { $...

This variable will give you a total number of fields in the current input record. awk -F',' '{print NF}' file.csv Example: $ cat file.csv col1,col2,col3,col4 col1,col2,col3 col1,col2 col1 col1,col2,col3,col4,col5 $ awk -F',' '{print NF}' file.csv 4 3 2 1 5