11using CouchDB . Driver . DTOs ;
2- using CouchDB . Driver . ExpressionVisitors ;
2+ using CouchDB . Driver . CompositeExpressionsEvaluator ;
33using CouchDB . Driver . Helpers ;
44using CouchDB . Driver . Settings ;
55using CouchDB . Driver . Types ;
@@ -29,49 +29,51 @@ public CouchQueryProvider(IFlurlClient flurlClient, CouchSettings settings, stri
2929
3030 public override string GetQueryText ( Expression expression )
3131 {
32- return Translate ( expression ) ;
32+ return Translate ( ref 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 ( ref 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
64- private string Translate ( Expression e )
63+ private string Translate ( ref Expression e )
6564 {
66- e = Evaluator . PartialEval ( e ) ;
67- var whereVisitor = new WhereExpressionVisitor ( ) ;
65+ e = Local . PartialEval ( e ) ;
66+ var whereVisitor = new BoolMemberToConstantEvaluator ( ) ;
6867 e = whereVisitor . Visit ( e ) ;
6968
69+ var pretranslator = new QueryPretranslator ( ) ;
70+ e = pretranslator . Visit ( e ) ;
71+
7072 return new QueryTranslator ( _settings ) . Translate ( e ) ;
7173 }
72-
73- public object GetCouchListOrFiltered < T > ( string body , MethodInfo filteringMethodInfo , Expression [ ] filteringExpressions )
74- {
74+
75+ public object GetCouchList < T > ( string body )
76+ {
7577 FindResult < T > result = _flurlClient
7678 . Request ( _connectionString )
7779 . AppendPathSegments ( _db , "_find" )
@@ -80,49 +82,116 @@ public object GetCouchListOrFiltered<T>(string body, MethodInfo filteringMethodI
8082 . SendRequest ( ) ;
8183
8284 var couchList = new CouchList < T > ( result . Docs . ToList ( ) , result . Bookmark , result . ExecutionStats ) ;
85+ return couchList ;
86+ }
8387
84- if ( filteringMethodInfo == null )
88+ private Expression RemoveUnsupportedMethodExpressions ( Expression expression , out bool hasUnsupportedMethods , IList < MethodCallExpression > unsupportedMethodCallExpressions )
89+ {
90+ if ( unsupportedMethodCallExpressions == null )
8591 {
86- return couchList ;
92+ throw new ArgumentNullException ( nameof ( unsupportedMethodCallExpressions ) ) ;
8793 }
8894
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 )
95+ // Search for method calls to run in-memory,
96+ // Once one is found all method calls after that must run in-memory.
97+ // The expression to translate in JSON ends with the last not in-memory call.
98+ bool IsUnsupportedMethodCallExpression ( Expression ex )
10099 {
101- ParameterInfo [ ] parameters = m . GetParameters ( ) ;
102- for ( var i = 0 ; i < filteringExpressions . Length ; i ++ )
100+ if ( ex is MethodCallExpression m )
103101 {
104- var lamdaExpression = filteringExpressions [ i ] as UnaryExpression ;
105- if ( lamdaExpression == null )
102+ Expression nextCall = m . Arguments [ 0 ] ;
103+ // Check if the next expression is unsupported
104+ var isUnsupported = IsUnsupportedMethodCallExpression ( nextCall ) ;
105+ if ( isUnsupported )
106106 {
107- return false ;
107+ unsupportedMethodCallExpressions . Add ( m ) ;
108+ return isUnsupported ;
108109 }
109-
110- if ( lamdaExpression . Operand . Type != parameters [ i + 1 ] . ParameterType )
110+ // If the next call is supported and the current is in the composite list
111+ if ( QueryTranslator . CompositeQueryableMethods . Contains ( m . Method . Name ) )
111112 {
112- return false ;
113+ unsupportedMethodCallExpressions . Add ( m ) ;
114+ return true ;
115+ }
116+ // If the next call is supported and the current is not in the supported list
117+ if ( ! QueryTranslator . NativeQueryableMethods . Contains ( m . Method . Name ) )
118+ {
119+ unsupportedMethodCallExpressions . Add ( m ) ;
120+ expression = nextCall ;
121+ return true ;
113122 }
114- invokeParameter [ i + 1 ] = lamdaExpression . Operand ;
115123 }
116- return true ;
124+ return false ;
117125 }
118126
119- MethodInfo rightOverload = filteringMethods . Single ( IsRightOverload ) ;
127+ hasUnsupportedMethods = IsUnsupportedMethodCallExpression ( expression ) ;
128+ return expression ;
129+ }
120130
121- MethodInfo enumerableGenericFilteringMethod = rightOverload . MakeGenericMethod ( typeof ( T ) ) ;
131+ private object InvokeUnsupportedMethodCallExpression ( object result , MethodCallExpression methodCallExpression )
132+ {
133+ MethodInfo queryableMethodInfo = methodCallExpression . Method ;
134+ Expression [ ] queryableMethodArguments = methodCallExpression . Arguments . ToArray ( ) ;
122135
136+ // Since Max and Min are not map 1 to 1 from Queryable to Enumerable
137+ // they need to be handled differently
138+ MethodInfo FindEnumerableMethod ( )
139+ {
140+ if ( queryableMethodInfo . Name == nameof ( Queryable . Max ) || queryableMethodInfo . Name == nameof ( Queryable . Min ) )
141+ {
142+ return FindEnumerableMinMax ( queryableMethodInfo ) ;
143+ }
144+ return typeof ( Enumerable ) . GetMethods ( ) . Single ( enumerableMethodInfo =>
145+ {
146+ return
147+ queryableMethodInfo . Name == enumerableMethodInfo . Name &&
148+ ReflectionComparator . IsCompatible ( queryableMethodInfo , enumerableMethodInfo ) ;
149+ } ) ;
150+ }
123151
124- var filtered = enumerableGenericFilteringMethod . Invoke ( null , invokeParameter ) ;
152+ // Find the equivalent method in Enumerable
153+ MethodInfo enumarableMethodInfo = FindEnumerableMethod ( ) ;
154+
155+ // Add the list as first parameter of the call
156+ var invokeParameter = new List < object > { result } ;
157+ // Convert everty other parameter expression to real values
158+ IEnumerable < object > enumerableParameters = queryableMethodArguments . Skip ( 1 ) . Select ( GetArgumentValueFromExpression ) ;
159+ // Add the other parameter to the complete list
160+ invokeParameter . AddRange ( enumerableParameters ) ;
161+
162+ Type [ ] requestedGenericParameters = enumarableMethodInfo . GetGenericMethodDefinition ( ) . GetGenericArguments ( ) ;
163+ Type [ ] genericParameters = queryableMethodInfo . GetGenericArguments ( ) ;
164+ Type [ ] usableParameters = genericParameters . Take ( requestedGenericParameters . Length ) . ToArray ( ) ;
165+ MethodInfo enumarableGenericMethod = enumarableMethodInfo . MakeGenericMethod ( usableParameters ) ;
166+ var filtered = enumarableGenericMethod . Invoke ( null , invokeParameter . ToArray ( ) ) ;
125167 return filtered ;
126168 }
169+
170+ private object GetArgumentValueFromExpression ( Expression e )
171+ {
172+ if ( e is ConstantExpression c )
173+ {
174+ return c . Value ;
175+ }
176+ if ( e is UnaryExpression u && u . Operand is LambdaExpression l )
177+ {
178+ return l . Compile ( ) ;
179+ }
180+ throw new NotImplementedException ( $ "Expression of type { e . NodeType } not supported.") ;
181+ }
182+
183+ private static MethodInfo FindEnumerableMinMax ( MethodInfo queryableMethodInfo )
184+ {
185+ Type [ ] genericParams = queryableMethodInfo . GetGenericArguments ( ) ;
186+ MethodInfo finalMethodInfo = typeof ( Enumerable ) . GetMethods ( ) . Single ( enumerableMethodInfo =>
187+ {
188+ Type [ ] enumerableArguments = enumerableMethodInfo . GetGenericArguments ( ) ;
189+ return
190+ enumerableMethodInfo . Name == queryableMethodInfo . Name &&
191+ enumerableArguments . Length == genericParams . Length - 1 &&
192+ enumerableMethodInfo . ReturnType == genericParams [ 1 ] ;
193+ } ) ;
194+ return finalMethodInfo ;
195+ }
127196 }
128197}
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