if your model got name, all your binding needs that name

<f:content><Label text="Code"/><Textvalue="{model>Code}"/><Label text="Lastname" /><Textvalue="{model>Lastname}"/></f:content>

are u using jsonmodel or odata model?

paste all your code here. and data structure

where and how have defined model ?

is GET_ENTITY method is implemented in data provider class ? check console and share if any errors

path should be :

oView.bindElement({
    path: "/Entities('" + oEvent.getParameter("arguments").Code + "')"
});

It is an odata model v4 .The model is defined in the manifest using a datasource.

"dataSources": {		
                          "manageservice": {
				"uri": "/destinations/testmodel/Service.svc/",
				"type": "OData",
				"settings": {
					"odataVersion": "4.0"
				},

"models": {
			"model": {
				"dataSource": "manageservice",
				"settings": {
					"synchronizationMode": "None",
					"operationMode": "Server",
					"groupId": "$direct"
				}

If I start my application all data are shown in the overview page. So in general the model is working correctly. Also if I navigate to the respective detail views I found following response in the network tab.

{"@odata.context":"$metadata#Entities","Code":"ABC","Name":"Sinclair"}

To check if "getentity" is working I simply accessed a single entity within the browser by using some kind of this URL:

https://domainname.com/service/Service.svc/Entities('ABC')

The entity(structred in xml) is looking like this:

<a:entry xmlns:a="http://www.w3.org/2005/Atom" xmlns:m="http://docs.oasis-open.org/odata/ns/metadata" xmlns:d="http://docs.oasis-open.org/odata/ns/data" m:context="$metadata#Entities">
<a:id>Entity(79b26e9a-b8e6-4d00-9fce-eb45c1a8a51b)</a:id>
<a:title/>
<a:summary/>
<a:updated>2017-04-10T08:08:37Z</a:updated>
<a:author>
<a:name/>

</a:author>

<a:link rel="edit" href="Entity(79b26e9a-b8e6-4d00-9fce-eb45c1a8a51b)"/>
<a:category scheme="http://docs.oasis-open.org/odata/ns/scheme" term="#OData.entity.entity"/>
<a:content type="application/xml">
<m:properties>
<d:Code>ABC</d:Code>
<d:Lastname>Sinclair</d:Lastname>

</m:properties>

</a:content>

</a:entry>

I still don`t get it why the context is not showing in respective fields of the detail view.

as per details you have provide only below has to be corrected:

1. "/Entities('" + oEvent.getParameter("arguments").Code + "')"
2. model name while element binding in details view ( you have incorporated now)
3. if still not working then, you can get that named model in onInit of details view controller and set back that model to detail view individually.

OR

1. remove model name from manifest file
2. Remove model reference from every bindings (first and second view)
3. and in details view bindElement like below:

oView.bindElement({
   path: "/Entities('" + oEvent.getParameter("arguments").Code + "')",
   //model: "model" //remove this line
});

"models": {
    "": { // remove 'model' from here and keep blank
    "dataSource": "manageservice",
    "settings": {
              "synchronizationMode": "None",
               "operationMode": "Server",
               "groupId": "$direct"
             } 
...........

if no luck, paste your all code including component, first controller and details code.

I followed up on the suggestions removing the model name. Also the first approach didn`t work. For testing purposes I bound a table to the detail view and data were shown but without any context. Of course the text fields can display then data for a selected entity.

Please find my code involved in the routing:

Component.js

sap.ui.define([
	"sap/ui/core/UIComponent",
	"sap/ui/Device",
	"testapplication/model/models"
], function(UIComponent, Device, models) {
	"use strict";

	return UIComponent.extend("trmaccelerator.Component", {
		metadata: {
			manifest: "json"
		},

		init: function() {
			// call the base component's init function
			UIComponent.prototype.init.apply(this, arguments);

			// set the device model
			this.setModel(models.createDeviceModel(), "device");
			
			// initialize router to create views based on url/hash 
			this.getRouter().initialize();
		}
	});
});

Manifest.json including Data Source, Model and Routing

"dataSources": {
	"source": {
		"uri": "/destinations/service/Service.svc/",
		"type": "OData",
		    "settings": {
		         "odataVersion": "4.0"
		     }
	}			
},

"models": {
	"model": {
		"dataSource": "source",
		"settings": {
			"synchronizationMode": "None",
			"operationMode": "Server",
			"groupId": "$direct"
	   }			
},

"routing": {
			"config": {
				"routerClass": "sap.m.routing.Router",
				"viewType": "XML",
				"viewPath": "trmaccelerator.view",
				"controlId": "idApp",
				"controlAggregation": "pages",
				"bypassed": {
					"target": "Error"
				},
				"async": true,
				"transition": "show"
			},
			"routes": [
				{
					"pattern": "",
					"name": "DisplayOverview",
					"target": "DisplayOverview"
				},
				
				{
					"pattern": "ShowObject/{Code}",
					"name": "ShowObject",
					"target": "ShowObject"
				}
				
			],
			"targets": {
				
				"DisplayOverview": {
					"viewName": "DisplayOverview",
					"viewId": "idDisplayOverview",
					"viewLevel": 1
				},
				"ShowObject": {
					"viewName": "ShowObject",
					"viewId": "idShowObject",
					"viewLevel": 2,
					"transition": "slide"
				},
			}
}

DisplayOverview.js

sap.ui.define([
	"sap/ui/core/mvc/Controller",
	"sap/ui/model/Filter",
	"sap/ui/model/FilterOperator",
	"sap/m/MessageToast"
	
	], function(Controller, Filter, FilterOperator, MessageToast) {
	"use strict";


	return Controller.extend("trmaccelerator.controller.DisplayOverview", {

	       onEditCurrencyButtonPressed:function(oEvent) {
		
			var oTable = this.getView().byId("idTableCodes");
			var oCode = oTable.getSelectedItem().getBindingContext("model").getProperty("Code");
			var oRouter = this.getOwnerComponent().getRouter();
			
			oRouter.navTo("ShowObject", {
				Code: oCode
			}); 
	      },	 
	});
});

DisplayOverview.xml

<mvc:View	controllerName="trmaccelerator.controller.DisplayOverview"
			xmlns:core="sap.ui.core" 
			xmlns:mvc="sap.ui.core.mvc" 
			xmlns="sap.m" 
			xmlns:html="http://www.w3.org/1999/xhtml"
			xmlns:l="sap.ui.layout"
			xmlns:f="sap.ui.layout.form"
			xmlns:fb="sap.ui.comp.filterbar">


	<App>
		<pages>
			<Page title="Overview">
				<content>
			
                                                 <Table	id="idTableCodes" 
							mode="SingleSelectLeft" 
							items="{ path: 'model>/Entities' }">
						
						<headerToolbar>
							<Toolbar>
								<Title text="Codes"/>
								<ToolbarSpacer></ToolbarSpacer> 
								<Button text = "Edit" press="onEditCurrencyButtonPressed" enabled = "true"/> 	
							</Toolbar>
						</headerToolbar>
						<columns>
						
							<Column>
								<Text text="Code"/>
							</Column>
							<Column>
								<Text text="Lastname"/>
							</Column>
				
						</columns>
						<items>
	                                               <ColumnListItem >
								<cells>
									<ObjectIdentifier text="{Code}"/>
									<Text text="{Name}"/>
								</cells>
							</ColumnListItem>
						</items>
					</Table>
				</content>
			</Page>
		</pages>
	</App>
</mvc:View>

ShowObject.js

onInit: function() {
	var oRouter = sap.ui.core.UIComponent.getRouterFor(this);
	oRouter.getRoute("ShowObject").attachMatched(this._onRouteMatched, this); 
},
			
	_onRouteMatched: function (oEvent) {
                       var oView = this.getView();
		       var oPath =  "/Entities('" + oEvent.getParameter("arguments").Code + "')";

                        oView.bindElement({
				path: oPath,
				model: "model"
			});					
	},

ShowObject.xml

<mvc:View	controllerName="trmaccelerator.controller.ShowObject"
			xmlns:html="http://www.w3.org/1999/xhtml" 
			xmlns:mvc="sap.ui.core.mvc"
			xmlns="sap.m"
			xmlns:l="sap.ui.layout"
			xmlns:f="sap.ui.layout.form"
			xmlns:core="sap.ui.core" >
	<App>
		<pages>
			<Page title="Change Codes"
			showNavButton="true"
			navButtonPress="onCurrencyBackButtonPressed"> 
		
				<VBox class="sapUiSmallMargin">
					<f:SimpleForm id="idForm"
						minWidth="1024"
						maxContainerCols="2"
						editable="false"
						layout="ResponsiveGridLayout"
						title="Change Codes"
						labelSpanL="2"
						labelSpanM="2"
						emptySpanL="0"
						emptySpanM="0"
						columnsL="1"
						columnsM="1">
						<f:content>
							<Label text="Currency ISO code"/>
							<Text value="{model>Code}"/>
							<Label text="Currency description" />
							<Text value="{model>Lastname}"/>
						</f:content>
					</f:SimpleForm>
				</VBox>
			</Page>
		</pages>
	</App>
</mvc:View>

I am surprised you are getting data displayed in table of DisplayOverview view even binding is not correct.

check my observations below:

1: in DisplayOverview view binding should be with model name like {model>Code},

2: in ShowObject.js try with attachPatternMatched

try: oRouter.getRoute("ShowObject").attachPatternMatched(this._onRouteMatched, this);

may help