How does ADO. NET Entity Framework output logs (ef4.0, log4net)

The EF team launched a complete set of cache and SQL Execution log solutions, efproviderwrappers. Their practice is to add a layer of packaging on the original EF provider, and use this layer of packaging interception for data caching and log monitoring. The cached data is the native data returned by the database after query, and is not an entity object. This avoids the extreme negative impact of the entity object status on the cache. In addition, this cache is transparent to upper-layer data queries, and within the same closed range, after the object type on which the cached data depends is updated (the corresponding table has a curd operation), the cache is automatically cleared. Log monitoring can be easily processed after this layer of packaging. You can download the original code from the previous link and compile and use it by yourself.

The following describes how to use it:
1. Download the source code compilation and add reference:
(1) efproviderwrappertoolkit. dll
(2) eftracingprovider. dll (used to output SQL)

(3) efcachingprovider. dll (for caching)

2. inherit an extended objectcontext from the generated objectcontext and define the required extended attributes. The focus is to redefine the constructor and generate the encapsulated entityconnection object.
Note:
(1) name = northwndentities the "northwndentities" here is the name of the connectionstring that generates EF in APP. config or web. config.
(2) "eftracingprovider", "efcachingprovider". If one is not used, delete the corresponding string.
Public extendednorthwindentities () <br/>: This ("name = northwindentities") <br/>{< br/>}< br/> Public extendednorthwindentities (string connectionstring) <br/>: Base (entityconnectionwrapperutils. createentityconnectionwithwrappers (<br/> connectionstring, <br/> "eftracingprovider", <br/> "efcachingprovider" <br/>) <br/>{< br/>}
 
3. Register provider in the application:
(1) if it is a winform application, you can call the following two statements of code at application startup to register the application.
Eftracingproviderconfiguration. registerprovider (); <br/> efcachingproviderconfiguration. registerprovider (); <br/>
(2) For a web application, you need to append the following configuration in Web. config: (same level as the system. Web node)
<System. DATA> <br/> <dbproviderfactories> <br/> <Add name = "Ef caching data provider" invariant = "efcachingprovider" Description = "caching provider wrapper" type = "efcachingprovider. efcachingproviderfactory, efcachingprovider, version = 1.0.0.0, culture = neutral, publickeytoken = def642f226e0e59b "/> <br/> <Add name =" Ef tracing data provider "invariant =" eftracingprovider "Description =" tracing provider wrapper "type =" eftracingprovider. eftracingproviderfactory, eftracingprovider, version = 1.0.0.0, culture = neutral, publickeytoken = Taobao "/> <br/> <Add name =" Ef generic provider wrapper "invariant =" efproviderwrapper "Description =" generic provider wrapper "type =" efproviderwrappertoolkit. efproviderwrapperfactory, efproviderwrappertoolkit, version = 1.0.0.0, culture = neutral, publickeytoken = def642f226e0e59b "/> <br/> </dbproviderfactories> <br/> </system. DATA> <br/>

How to append log4net output:
According to the above steps, some code is added to the extension class of objectcontext. For details, see the comments in the Code:
Public partial class extendednorthwindentities: northwndentities <br/>{< br/> Private Static ilog logger; <br/> static extendednorthwindentities () <br/>{< br/> // register tracingprovider <br/> eftracingproviderconfiguration. registerprovider (); <br/> // initialize log4net, Which is configured in an independent "log4net. config ". <br/> log4net. config. xmlconfigurator. configure (New fileinfo ("log4net. config "); <br/> // initialize a logger <br/> logger = log4net. logmanager. getlogger ("eflog4net"); <br/>}< br/> Public extendednorthwindentities () <br/>: This ("name = northwndentities ") <br/>{< br/> // bind the commandexecuting event of eftracingconnection, and output log <br/> This. unwrapconnection <eftracingconnection> (). commandexecuting + = (S, e) => <br/>{< br/> // output tracestring (SQL) <br/> logger. debug (environment. newline + E. totracestring (). trimend (); <br/>}; <br/>}< br/> Public extendednorthwindentities (string connectionstring) <br/>: Base (entityconnectionwrapperutils. createentityconnectionwithwrappers (<br/> connectionstring, <br/> "eftracingprovider" <br/>) <br/>{< br/>}< br/>}
The configuration of log4net. config is as follows: (for other detailed configuration instructions of log4net, refer to the http://logging.apache.org/log4net/release/config-examples.html)
<? XML version = "1.0" encoding = "UTF-8"?> <Br/> <configuration> <br/> <log4net> <br/> <root> <br/> <level value = "all"/> <br/> <appender -Ref ref = "rollingfileappender"/> <br/> <appender-ref = "leleappender"/> <br/> </root> <br/> <appender name = "rollingfileappender" type = "log4net. appender. rollingfileappender, log4net "> <br/> <Param name =" file "value = ".. /.. /logs/eflogs.txt "/> <br/> <Param name =" appendtofile "value =" true "/> <br/> <para M name = "rollingstyle" value = "date"/> <br/> <Param name = "datepattern" value = "YYYY. mm. dd "/> <br/> <Param name =" staticlogfilename "value =" true "/> <br/> <layout type =" log4net. layout. patternlayout, log4net "> <br/> <Param name =" conversionpattern "value =" % d [% T] %-5 p % C-% m % N "/> <br/> </layout> <br/> </appender> <br/> <appender name = "leleappender" type = "log4net. appender. coloredconsoleappender, log4 Net "> <br/> <mapping> <br/> <level value =" debug "/> <br/> <! -- <Forecolor value = "white"/> --> <br/> <backcolor value = "cyan, highintensity "/> <br/> </mapping> <br/> <layout type =" log4net. layout. patternlayout, log4net "> <br/> <Param name =" conversionpattern "value =" % d [% T] [%-5 p] % C-% m % N "/> <br/> </layout> <br/> </appender> <br/> </log4net> <br/> </configuration>
 
In this way, you can control the SQL output generated by EF through the log4net configuration file. In the above log4net, two appender are configured. One is output to the console, and the other is output to eflogs.txt.
Next, call EF to see the output log:
Static void main (string [] ARGs) <br/>{< br/> using (var db = new extendednorthwindentities ()) <br/> {<br/> var toyproducts = from P in dB. products <br/> where p. category. categoryname. contains ("seafood") <br/> select new {P. category. categoryname, P. productname, P. unitprice }; <br/> console. writeline ("-----------------"); <br/> foreach (var p in toyproducts) <br/> console. writeline ("{0,-10} {1,-35} {2, 10}", p. categoryname, P. productname, P. unitprice); <br/>}< br/> console. read (); <br/>}

 

 

The above blue background output is the SQL log configured and output through log4net. In addition, efproviderwrappers not only provides the log output functions, but also provides important functions for caching. In the next article, I will focus on how to use efproviderwrappers to implement data caching.