ASP.NET Core 3.1 Identity tables in MySQL

To have identity tables in MySQL install Pomelo package, set the connection string and DBContext in Startup.cs like this:

services.AddDbContext(options => options.UseMySql(Configuration.GetConnectionString("MySqlConnection"));

Open NuGet > Package Manager Console
Run: EntityFrameworkCore\Update-Database -Verbose
Run: update-database

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XPATH cheatsheet

This post was inspired by great this find, which I managed to search while working on one project. It happens few times in the past that some interested content was not available any more and in order to save this great cheatsheet I am copying it from LeCoupa

// XPath CheatSheet
// To test XPath in your Chrome Debugger: $x('/html/body')
// https://www.jittuu.com/2012/2/14/Testing-XPath-In-Chrome/


// 0. XPath Examples.
// More: https://xpath.alephzarro.com/content/cheatsheet.html


'//hr[@class="edge" and position()=1]'                // every first hr of 'edge' class
'//table[count(tr)=1 and count(tr/td)=2]'             // all tables with 1 row and 2 cols
'//div/form/parent::*'                                // all divs that have form
'./div/b'                                             // a relative path
'//table[parent::div[@class="pad"] and not(@id)]//a'  // any anchor in a table without id, contained in a div of "pad" class
'/html/body/div/*[preceding-sibling::h4]'             // give me whatever after h4
'//tr/td[font[@class="head" and text()="TRACK"]]'     // all td that has font of a "head" class and text "TRACK"
'./table/tr[last()]'                                  // the last row of a table
'//rdf:Seq/rdf:li/em:id'                              // using namespaces
'//a/@href'                                           // hrefs of all anchors
'//*[count(*)=3]'                                     // all nodes with 3 children
'//var|//acronym'                                     // all vars and acronyms


// 1. General.


'/html'                     // whole web page (css: html)
'/html/body'                // whole web page body (css: body)
'//text()'                  // all text nodes of web page
'/html/body/.../.../.../E'  // element <E> by absolute reference (css: body > … > … > … > E)


// 2. Tag.


'//E'                                        // element <E> by relative reference (css: E)
'(//E)[2]'                                   // second <E> element anywhere on page
'//img'                                      // image element (css: img)
'//E[@A]'                                    // element <E> with attribute A (css: E[A])
'//E[@A="t"]'                                // element <E> with attribute A containing text 't' exactly (css: E[A='t'])
'//E[contains(@A,"t")]'                      // element <E> with attribute A containing text 't' (css: E[A*='t'])
'//E[starts-with(@A, "t")]'                  // element <E> whose attribute A begins with 't' (css: E[A^='t'])
'//E[ends-with(@A, "t")]'                    // element <E> whose attribute A ends with 't' (css: E[A$='t'])
'//E[contains(concat(" ", @A, " "), " w ")'  // element <E> with attribute A containing word 'w' (css: E[A~='w'])
'//E[matches(@A, "r")]'                      // element <E> with attribute A matching regex ‘r’
'//E1[@id=I1] | //E2[@id=I2]'                // element <E1> with id I1 or element <E2> with id I2 (css: E1#I1, E2#I2)
'//E1[@id=I1 or @id=I2]'                     // element <E1> with id I1 or id I2 (css: E1#I1, E1#I2)


// 3. Attribute.


'//E/@A'                    // attribute A of element <E> (css: E@A)
'//*/@A'                    // attribute A of any element (css: *@A)
'//E[@A2="t"]/@A1'          // attribute A1 of element <E> where attribute A2 is 't' exactly (css: E[A2='t']@A1)
'//E[contains(@A,"t")]/@A'  // attribute A of element <E> where A contains 't' (css: E[A*='t']@A)


// 4. ID & Name.


'//*[@id="I"]'                // element with id I (css: #I)
'//E[@id="I"]'                // element <E> with id I (css: E#I)
'//*[@name="N"]'              // element with name (css: [name='N'])
'//E[@name="N"]'              // element <E> with name (css: E[name='N'])
'//*[@id="X" or @name="X"]'   // element with id X or, failing that, a name X
'//*[@name="N"][v+1]'         // element with name N & specified 0-based index ‘v’ (css: [name='N']:nth-child(v+1))
'//*[@name="N"][@value="v"]'  // element with name N & specified value ‘v’ (css: *[name='N'][value='v’])


// 5. Lang & Class.


'//E[@lang="L" or starts-with(@lang, concat("L", "-"))]'  // element <E> is explicitly in language L or subcode (css: E[lang|=L])
'//*[contains(concat(" ", @class, " "), " C ")]'          // element with a class C (css: .C)
'//E[contains(concat(" ", @class, " "), " C ")]'          // element <E> with a class C (css: E.C)


// 6. Text & Link.


'//*[.="t"]'                  // element containing text 't' exactly
'//E[contains(text(), "t")]'  // element <E> containing text 't' (css: E:contains('t'))
'//a'                         // link element (css: a)
'//a[.="t"]'                  // element <a> containing text 't' exactly
'//a[contains(text(), "t")]'  // element <a> containing text 't' (css: a:contains('t'))
'//a[@href="url"]'            // <a> with target link 'url' (css: a[href='url'])
'//a[.="t"]/@href'            // link URL labeled with text 't' exactly


// 7. Parent & Child.


'//E/*[1]'                                                        // first child of element <E> (css: E > *:first-child)
'//E[1]'                                                          // first <E> child (css: E:first-of-type)
'//E/*[last()]'                                                   // last child of element E (css: E *:last-child)
'//E[last()]'                                                     // last <E> child (css: E:last-of-type)
'//E[2]'                                                          // second <E> child (css: E:nth-of-type(2))
'//*[2][name()="E"]'                                              // second child that is an <E> element (css: E:nth-child(2))
'//E[last()-1]'                                                   // second-to-last <E> child (css: E:nth-last-of-type(2))
'//*[last()-1][name()="E"]'                                       // second-to-last child that is an <E> element (css: E:nth-last-child(2))
'//E1/[E2 and not( *[not(self::E2)])]'                            // element <E1> with only <E2> children
'//E/..'                                                          // parent of element <E>
'//*[@id="I"]/.../.../.../E'                                      // descendant <E> of element with id I using specific path (css: #I > … > … > … > E)
'//*[@id="I"]//E'                                                 // descendant <E> of element with id I using unspecified path (css: #I E)
'//E[count(*)=0]'                                                 // element <E> with no children (E:empty)
'//E[count(*)=1]'                                                 // element <E> with an only child
'//E[count(preceding-sibling::*)+count(following-sibling::*)=0]'  // element <E> that is an only child (css: E:only-child)
'//E[count(../E) = 1]'                                            // element <E> with no <E> siblings (css: E:only-of-type)
'//E[position() mod N = M + 1]'                                   // every Nth element starting with the (M+1)th (css: E:nth-child(Nn+M))


// 8. Sibling.


'//E2/following-sibling::E1'                 // element <E1> following some sibling <E2> (css: E2 ~ E1)
'//E2/following-sibling::*[1][name()="E1"]'  // element <E1> immediately following sibling <E2> (css: E2 + E1)
'//E2/following-sibling::*[2][name()="E1"]'  // element <E1> following sibling <E2> with one intermediary (css: E2 + * + E1)
'//E/following-sibling::*'                   // sibling element immediately following <E> (css: E + *)
'//E2/preceding-sibling::E1'                 // element <E1> preceding some sibling <E2>
'//E2/preceding-sibling::*[1][name()="E1"]'  // element <E1> immediately preceding sibling <E2>
'//E2/preceding-sibling::*[2][name()="E1"]'  // element <E1> preceding sibling <E2> with one intermediary
'//E/preceding-sibling::*[1]'                // sibling element immediately preceding <E>


// 9. Table Cell.


'//*[@id="TestTable"]//tr[3]//td[2]'          // cell by row and column (e.g. 3rd row, 2nd column) (css: #TestTable tr:nth-child(3) td:nth-child(2))
'//td[preceding-sibling::td="t"]'             // cell immediately following cell containing 't' exactly
'td[preceding-sibling::td[contains(.,"t")]]'  // cell immediately following cell containing 't' (css: td:contains('t') ~ td)


// 10. Dynamic.


'//E[@disabled]'       // user interface element <E> that is disabled (css: E:disabled)
'//*[not(@disabled)]'  // user interface element that is enabled (css: E:enabled)
'//*[@checked]'        // checkbox (or radio button) that is checked (css: *:checked)


// 11. XPath Functions.
// https://developer.mozilla.org/en-US/docs/Web/XPath/Functions


// 11.1. Conversion.


boolean(expression)  // evaluates an expression and returns true or false.
string([object])     // converts the given argument to a string.
number([object])     // converts an object to a number and returns the number.


// 11.2. Math.


ceiling(number)  // evaluates a decimal number and returns the smallest integer greater than or equal to the decimal number.
floor(number)    // evaluates a decimal number and returns the largest integer less than or equal to the decimal number.
round(decimal)   // returns a number that is the nearest integer to the given number.
sum(node-set)    // returns a number that is the sum of the numeric values of each node in a given node-set.


// 11.3. Logic.


true()           // returns a boolean value of true.
false()          // returns boolean false.
not(expression)  // evaluates a boolean expression and returns the opposite value.


// 11.4. Node.


lang(string)               // determines whether the context node matches the given language and returns boolean true or false.
name([node-set])           // returns a string representing the QName of the first node in a given node-set.
namespace-uri([node-set])  // returns a string representing the namespace URI of the first node in a given node-set.


// 11.5. Context.


count(node-set)           // counts the number of nodes in a node-set and returns an integer.
function-available(name)  // determines if a given function is available and returns boolean true or false.
last()                    // returns a number equal to the context size from the expression evaluation context.
position()                // returns a number equal to the context position from the expression evaluation context.


// 11.6. String.


contains(haystack-string, needle-string)  // determines whether the first argument string contains the second argument string and returns boolean true or false.
concat(string1, string2 [stringn]*)       // concatenates two or more strings and returns the resulting string.
normalize-space(string)                   // strips leading and trailing white-space from a string, replaces sequences of whitespace characters by a single space, and returns the resulting string.
starts-with(haystack, needle)             // checks whether the first string starts with the second string and returns true or false.
string-length([string])                   // returns a number equal to the number of characters in a given string.
substring(string, start [length])         // returns a part of a given string.
substring-after(haystack, needle)         // returns a string that is the rest of a given string after a given substring.
substring-before(haystack, needle)        // returns a string that is the rest of a given string before a given substring.
translate(string, abc, XYZ)               // evaluates a string and a set of characters to translate and returns the translated string.


// 12. XPath Axes.

ancestor            // indicates all the ancestors of the context node beginning with the parent node and traveling through to the root node.
ancestor-or-self    // indicates the context node and all of its ancestors, including the root node.
attribute (@)       // indicates the attributes of the context node. Only elements have attributes. This axis can be abbreviated with the at sign (@).
child (/)           // indicates the children of the context node. If an XPath expression does not specify an axis, this is understood by default. Since only the root node or element nodes have children, any other use will select nothing.
descendant (//)     // indicates all of the children of the context node, and all of their children, and so forth. Attribute and namespace nodes are not included - the parent of an attribute node is an element node, but attribute nodes are not the children of their parents.
descendant-or-self  // indicates the context node and all of its descendants. Attribute and namespace nodes are not included - the parent of an attribute node is an element node, but attribute nodes are not the children of their parents.
following           // indicates all the nodes that appear after the context node, except any descendant, attribute, and namespace nodes.
following-sibling   // indicates all the nodes that have the same parent as the context node and appear after the context node in the source document.
parent(..)          // indicates the single node that is the parent of the context node. It can be abbreviated as two periods (..).
preceding           // indicates all the nodes that precede the context node in the document except any ancestor, attribute and namespace nodes.
preceding-sibling   // indicates all the nodes that have the same parent as the context node and appear before the context node in the source document.
self (.)            // indicates the context node itself. It can be abbreviated as a single period (.).
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Entity Framework in .NET and MySQL tinymce(1) problem

You know at tinymce(1) field in MySQL database will be converted to boolean type in C#. Sometimes you don’t want this because you just want to read the integer value from MySQL in this field (it can be any from 0-255 if unsigned or -127-127 if signed) – one byte.

In order to do so you need to do two things:

  1. Add TreatTinyAsBoolean=false to your connection string
  2. Edit the database edmx file and in SSDL content section change bool to tinyint, and in CSDL content section change Boolean into SByte.

Be careful if you update edmx file because changes you have made will be lost. This is the bad thing about this, but it is working solution.

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Microsoft .NET to run on Linux and Mac OS X

Microsoft .NET will finally run fully on Linux and Mac OS X platform and this is a great news.

Visual Studio is maybe the best tool for developers and Microsoft decided to open sourcing the full server-side .NET Core stack, from ASP.NET 5 down to Core Runtime and Framework.

Microsoft is also giving for free Visual Studio Community 2013 full featured edition of Visual Studio, available today.

You can watch more about this here.

Open source links
ASP.NET – https://github.com/aspnet/home
.NET Compiler – https://roslyn.codeplex.com/
.NET Core – https://github.com/dotnet/corefx
.NET – https://github.com/Microsoft/dotnet

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