DATAMONGO-1290 - Move parameter binding for String based queries.

Moved parameter binding for string based queries into separate class.

Author: christophstrobl

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/query/ExpressionEvaluatingParameterBinder.java

@@ -0,0 +1,230 @@
+/*
+ * Copyright 2015 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mongodb.repository.query;
+
+import java.util.Collections;
+import java.util.List;
+
+import javax.xml.bind.DatatypeConverter;
+
+import org.bson.BSON;
+import org.springframework.data.mongodb.repository.query.StringBasedMongoQuery.ParameterBinding;
+import org.springframework.data.repository.query.EvaluationContextProvider;
+import org.springframework.expression.EvaluationContext;
+import org.springframework.expression.Expression;
+import org.springframework.expression.spel.standard.SpelExpressionParser;
+import org.springframework.util.Assert;
+import org.springframework.util.CollectionUtils;
+import org.springframework.util.StringUtils;
+
+import com.mongodb.util.JSON;
+
+/**
+ * {@link ExpressionEvaluatingParameterBinder} allows to evaluate, convert and bind parameters to placholders within a
+ * {@link String}.
+ * 
+ * @author Christoph Strobl
+ * @author Thomas Darimont
+ * @since 1.9
+ */
+class ExpressionEvaluatingParameterBinder {
+
+	private final SpelExpressionParser expressionParser;
+	private final EvaluationContextProvider evaluationContextProvider;
+
+	/**
+	 * Creates new {@link ExpressionEvaluatingParameterBinder}
+	 * 
+	 * @param expressionParser must not be {@literal null}.
+	 * @param evaluationContextProvider must not be {@literal null}.
+	 */
+	public ExpressionEvaluatingParameterBinder(SpelExpressionParser expressionParser,
+			EvaluationContextProvider evaluationContextProvider) {
+
+		Assert.notNull(expressionParser, "ExpressionParser must not be null!");
+		Assert.notNull(evaluationContextProvider, "EvaluationContextProvider must not be null!");
+
+		this.expressionParser = expressionParser;
+		this.evaluationContextProvider = evaluationContextProvider;
+	}
+
+	/**
+	 * Bind values provided by {@link MongoParameterAccessor} to placeholders in {@literal raw} while consisdering
+	 * potential conversions and parameter types.
+	 * 
+	 * @param raw
+	 * @param accessor
+	 * @param bindingContext
+	 * @return {@literal null} if given {@literal raw} value is empty.
+	 */
+	public String bind(String raw, MongoParameterAccessor accessor, BindingContext bindingContext) {
+
+		if (!StringUtils.hasText(raw)) {
+			return null;
+		}
+
+		return replacePlaceholders(raw, accessor, bindingContext);
+	}
+
+	/**
+	 * Replaced the parameter place-holders with the actual parameter values from the given {@link ParameterBinding}s.
+	 * 
+	 * @param input
+	 * @param accessor
+	 * @param parameters
+	 * @param bindings
+	 * @return
+	 */
+	private String replacePlaceholders(String input, MongoParameterAccessor accessor, BindingContext bindingContext) {
+
+		if (!bindingContext.hasBindings()) {
+			return input;
+		}
+
+		boolean isCompletlyParameterizedQuery = input.matches("^\\?\\d+$");
+
+		StringBuilder result = new StringBuilder(input);
+
+		for (ParameterBinding binding : bindingContext.getBindings()) {
+
+			String parameter = binding.getParameter();
+			int idx = result.indexOf(parameter);
+
+			if (idx != -1) {
+				String valueForBinding = getParameterValueForBinding(accessor, bindingContext.getParameters(), binding);
+
+				// if the value to bind is an object literal we need to remove the quoting around
+				// the expression insertion point.
+				boolean shouldPotentiallyRemoveQuotes = valueForBinding.startsWith("{") && !isCompletlyParameterizedQuery;
+
+				int start = idx;
+				int end = idx + parameter.length();
+
+				if (shouldPotentiallyRemoveQuotes) {
+
+					// is the insertion point actually surrounded by quotes?
+					char beforeStart = result.charAt(start - 1);
+					char afterEnd = result.charAt(end);
+
+					if ((beforeStart == '\'' || beforeStart == '"') && (afterEnd == '\'' || afterEnd == '"')) {
+
+						// skip preceeding and following quote
+						start -= 1;
+						end += 1;
+					}
+				}
+
+				result.replace(start, end, valueForBinding);
+			}
+		}
+
+		return result.toString();
+	}
+
+	/**
+	 * Returns the serialized value to be used for the given {@link ParameterBinding}.
+	 * 
+	 * @param accessor
+	 * @param parameters
+	 * @param binding
+	 * @return
+	 */
+	private String getParameterValueForBinding(MongoParameterAccessor accessor, MongoParameters parameters,
+			ParameterBinding binding) {
+
+		Object value = binding.isExpression() ? evaluateExpression(binding.getExpression(), parameters,
+				accessor.getValues()) : accessor.getBindableValue(binding.getParameterIndex());
+
+		if (value instanceof String && binding.isQuoted()) {
+			return (String) value;
+		}
+
+		if (value instanceof byte[]) {
+
+			String base64representation = DatatypeConverter.printBase64Binary((byte[]) value);
+			if (!binding.isQuoted()) {
+				return "{ '$binary' : '" + base64representation + "', '$type' : " + BSON.B_GENERAL + "}";
+			}
+			return base64representation;
+		}
+
+		return JSON.serialize(value);
+	}
+
+	/**
+	 * Evaluates the given {@code expressionString}.
+	 * 
+	 * @param expressionString
+	 * @param parameters
+	 * @param parameterValues
+	 * @return
+	 */
+	private Object evaluateExpression(String expressionString, MongoParameters parameters, Object[] parameterValues) {
+
+		EvaluationContext evaluationContext = evaluationContextProvider.getEvaluationContext(parameters, parameterValues);
+		Expression expression = expressionParser.parseExpression(expressionString);
+
+		return expression.getValue(evaluationContext, Object.class);
+	}
+
+	/**
+	 * @author Christoph Strobl
+	 * @since 1.9
+	 */
+	static class BindingContext {
+
+		final MongoParameters parameters;
+		final List<ParameterBinding> bindings;
+
+		/**
+		 * Creates new {@link BindingContext}.
+		 * 
+		 * @param parameters
+		 * @param bindings
+		 */
+		public BindingContext(MongoParameters parameters, List<ParameterBinding> bindings) {
+
+			this.parameters = parameters;
+			this.bindings = bindings;
+		}
+
+		/**
+		 * @return {@literal true} when list of bindings is not empty.
+		 */
+		boolean hasBindings() {
+			return !CollectionUtils.isEmpty(bindings);
+		}
+
+		/**
+		 * Get unmodifiable list of {@link ParameterBinding}s.
+		 * 
+		 * @return never {@literal null}.
+		 */
+		public List<ParameterBinding> getBindings() {
+			return Collections.unmodifiableList(bindings);
+		}
+
+		/**
+		 * Get the associated {@link MongoParameters}.
+		 * 
+		 * @return
+		 */
+		public MongoParameters getParameters() {
+			return parameters;
+		}
+
+	}
+}