@@ -32,32 +32,31 @@ public override string GetQueryText(Expression expression)
3232 return Translate ( expression ) ;
3333 }
3434
35- public override object Execute ( Expression e , bool completeResponse )
35+ public override object Execute ( Expression expression , bool completeResponse )
3636 {
37- MethodInfo _filterMethodInfo = null ;
38- Expression [ ] _filteringExpressions = Array . Empty < Expression > ( ) ;
39- if ( e is MethodCallExpression m )
37+ // Remove from the expressions tree all IQueryable methods not supported by CouchDB and put them into the list
38+ var unsupportedMethodCallExpressions = new List < MethodCallExpression > ( ) ;
39+ expression = RemoveUnsupportedMethodExpressions ( expression , out var hasUnsupportedMethods , unsupportedMethodCallExpressions ) ;
40+
41+ var body = Translate ( expression ) ;
42+ Type elementType = TypeSystem . GetElementType ( expression . Type ) ;
43+
44+ // Create generic GetCouchList method and invoke it, sending the request to CouchDB
45+ MethodInfo method = typeof ( CouchQueryProvider ) . GetMethod ( nameof ( CouchQueryProvider . GetCouchList ) ) ;
46+ MethodInfo generic = method . MakeGenericMethod ( elementType ) ;
47+ var result = generic . Invoke ( this , new [ ] { body } ) ;
48+
49+ // If no unsupported methods, return the result
50+ if ( ! hasUnsupportedMethods )
4051 {
41- if (
42- m . Method . Name == "First" ||
43- m . Method . Name == "FirstOrDefault" ||
44- m . Method . Name == "Last" ||
45- m . Method . Name == "LastOrDefault" ||
46- m . Method . Name == "Single" ||
47- m . Method . Name == "SingleOrDefault" )
48- {
49- _filterMethodInfo = m . Method ;
50- _filteringExpressions = m . Arguments . Skip ( 1 ) . ToArray ( ) ;
51- e = m . Arguments [ 0 ] ;
52- }
52+ return result ;
5353 }
5454
55- var body = Translate ( e ) ;
56- Type elementType = TypeSystem . GetElementType ( e . Type ) ;
57-
58- MethodInfo method = typeof ( CouchQueryProvider ) . GetMethod ( nameof ( CouchQueryProvider . GetCouchListOrFiltered ) ) ;
59- MethodInfo generic = method . MakeGenericMethod ( elementType ) ;
60- var result = generic . Invoke ( this , new [ ] { body , ( object ) _filterMethodInfo , _filteringExpressions } ) ;
55+ // For every unsupported method expression, execute it on the result
56+ foreach ( MethodCallExpression inMemoryCall in unsupportedMethodCallExpressions )
57+ {
58+ result = InvokeUnsupportedMethodCallExpression ( result , inMemoryCall ) ;
59+ }
6160 return result ;
6261 }
6362
@@ -69,9 +68,9 @@ private string Translate(Expression e)
6968
7069 return new QueryTranslator ( _settings ) . Translate ( e ) ;
7170 }
72-
73- public object GetCouchListOrFiltered < T > ( string body , MethodInfo filteringMethodInfo , Expression [ ] filteringExpressions )
74- {
71+
72+ public object GetCouchList < T > ( string body )
73+ {
7574 FindResult < T > result = _flurlClient
7675 . Request ( _connectionString )
7776 . AppendPathSegments ( _db , "_find" )
@@ -80,49 +79,84 @@ public object GetCouchListOrFiltered<T>(string body, MethodInfo filteringMethodI
8079 . SendRequest ( ) ;
8180
8281 var couchList = new CouchList < T > ( result . Docs . ToList ( ) , result . Bookmark , result . ExecutionStats ) ;
82+ return couchList ;
83+ }
8384
84- if ( filteringMethodInfo == null )
85+ private Expression RemoveUnsupportedMethodExpressions ( Expression expression , out bool hasUnsupportedMethods , IList < MethodCallExpression > unsupportedMethodCallExpressions )
86+ {
87+ if ( unsupportedMethodCallExpressions == null )
8588 {
86- return couchList ;
89+ throw new ArgumentNullException ( nameof ( unsupportedMethodCallExpressions ) ) ;
8790 }
8891
89- var filteringMethods = typeof ( Enumerable ) . GetMethods ( )
90- . Where ( m =>
91- m . Name == filteringMethodInfo . Name &&
92- m . GetParameters ( ) . Length - 1 == filteringExpressions . Length )
93- . OrderBy ( m => m . GetParameters ( ) . Length ) . ToList ( ) ;
94-
95-
96- var invokeParameter = new object [ filteringExpressions . Length + 1 ] ;
97- invokeParameter [ 0 ] = couchList ;
98-
99- bool IsRightOverload ( MethodInfo m )
92+ // Search for method calls to run in-memory,
93+ // Once one is found all method calls after that must run in-memory.
94+ // The expression to translate in JSON ends with the last not in-memory call.
95+ bool IsUnsupportedMethodCallExpression ( Expression ex )
10096 {
101- ParameterInfo [ ] parameters = m . GetParameters ( ) ;
102- for ( var i = 0 ; i < filteringExpressions . Length ; i ++ )
97+ if ( ex is MethodCallExpression m )
10398 {
104- var lamdaExpression = filteringExpressions [ i ] as UnaryExpression ;
105- if ( lamdaExpression == null )
99+ Expression nextCall = m . Arguments [ 0 ] ;
100+ // Check if the next expression is unsupported
101+ var isUnsupported = IsUnsupportedMethodCallExpression ( nextCall ) ;
102+ if ( isUnsupported )
106103 {
107- return false ;
104+ unsupportedMethodCallExpressions . Add ( m ) ;
105+ return isUnsupported ;
108106 }
109-
110- if ( lamdaExpression . Operand . Type != parameters [ i + 1 ] . ParameterType )
107+ // If the next call is supported and the current is not in the supported list
108+ if ( ! QueryTranslator . NativeQueryableMethods . Contains ( m . Method . Name ) )
111109 {
112- return false ;
110+ unsupportedMethodCallExpressions . Add ( m ) ;
111+ expression = nextCall ;
112+ return true ;
113113 }
114- invokeParameter [ i + 1 ] = lamdaExpression . Operand ;
115114 }
116- return true ;
115+ return false ;
117116 }
118117
119- MethodInfo rightOverload = filteringMethods . Single ( IsRightOverload ) ;
120-
121- MethodInfo enumerableGenericFilteringMethod = rightOverload . MakeGenericMethod ( typeof ( T ) ) ;
122-
118+ hasUnsupportedMethods = IsUnsupportedMethodCallExpression ( expression ) ;
119+ return expression ;
120+ }
123121
124- var filtered = enumerableGenericFilteringMethod . Invoke ( null , invokeParameter ) ;
122+ private object InvokeUnsupportedMethodCallExpression ( object result , MethodCallExpression methodCallExpression )
123+ {
124+ MethodInfo queryableMethodInfo = methodCallExpression . Method ;
125+ Expression [ ] queryableMethodArguments = methodCallExpression . Arguments . ToArray ( ) ;
126+ // Find the equivalent method in Enumerable
127+ MethodInfo enumarableMethodInfo = typeof ( Enumerable ) . GetMethods ( ) . Single ( enumerableMethodInfo =>
128+ {
129+ return
130+ queryableMethodInfo . Name == enumerableMethodInfo . Name &&
131+ ReflectionComparator . IsCompatible ( queryableMethodInfo , enumerableMethodInfo ) ;
132+ } ) ;
133+
134+ // Add the list as first parameter of the call
135+ var invokeParameter = new List < object > { result } ;
136+ // Convert everty other parameter expression to real values
137+ IEnumerable < object > enumerableParameters = queryableMethodArguments . Skip ( 1 ) . Select ( GetArgumentValueFromExpression ) ;
138+ // Add the other parameter to the complete list
139+ invokeParameter . AddRange ( enumerableParameters ) ;
140+
141+ Type [ ] requestedGenericParameters = enumarableMethodInfo . GetGenericMethodDefinition ( ) . GetGenericArguments ( ) ;
142+ Type [ ] genericParameters = queryableMethodInfo . GetGenericArguments ( ) ;
143+ Type [ ] usableParameters = genericParameters . Take ( requestedGenericParameters . Length ) . ToArray ( ) ;
144+ MethodInfo enumarableGenericMethod = enumarableMethodInfo . MakeGenericMethod ( usableParameters ) ;
145+ var filtered = enumarableGenericMethod . Invoke ( null , invokeParameter . ToArray ( ) ) ;
125146 return filtered ;
126147 }
148+
149+ private object GetArgumentValueFromExpression ( Expression e )
150+ {
151+ if ( e is ConstantExpression c )
152+ {
153+ return c . Value ;
154+ }
155+ if ( e is UnaryExpression u && u . Operand is LambdaExpression l )
156+ {
157+ return l . Compile ( ) ;
158+ }
159+ throw new NotImplementedException ( $ "Expression of type { e . NodeType } not supported.") ;
160+ }
127161 }
128162}
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