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* fix(iot-device): TryGetValue methods should check for the component…
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… identifier when applicable and should not throw any exceptions (#2111)
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@abhipsaMisra
abhipsaMisra authored Jul 20, 2021
1 parent 058035b commit 22fb865
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Showing 4 changed files with 298 additions and 42 deletions.
74 changes: 56 additions & 18 deletions iothub/device/src/ClientPropertyCollection.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -170,8 +170,9 @@ public bool Contains(string componentName, string propertyName)
/// <typeparam name="T">The type to cast the object to.</typeparam>
/// <param name="componentName">The component which holds the required property.</param>
/// <param name="propertyName">The property to get.</param>
/// <param name="propertyValue">The value of the component-level property.</param>
/// <returns>true if the property collection contains a component level property with the specified key; otherwise, false.</returns>
/// <param name="propertyValue">When this method returns true, this contains the value of the component-level property.
/// When this method returns false, this contains the default value of the type <c>T</c> passed in.</param>
/// <returns>True if a component-level property of type <c>T</c> with the specified key was found; otherwise, it returns false.</returns>
public virtual bool TryGetValue<T>(string componentName, string propertyName, out T propertyValue)
{
if (Logging.IsEnabled && Convention == null)
Expand All @@ -180,35 +181,72 @@ public virtual bool TryGetValue<T>(string componentName, string propertyName, ou
$"TryGetValue will attempt to get the property value but may not behave as expected.", nameof(TryGetValue));
}

// If either the component name or the property name is null, empty or whitespace,
// then return false with the default value of the type <T> passed in.
if (string.IsNullOrWhiteSpace(componentName) || string.IsNullOrWhiteSpace(propertyName))
{
propertyValue = default;
return false;
}

if (Contains(componentName, propertyName))
{
object componentProperties = Collection[componentName];

// If the ClientPropertyCollection was constructed by the user application (eg. for updating the client properties)
// then the componentProperties are retrieved as a dictionary.
// The required property value can be fetched from the dictionary directly.
if (componentProperties is IDictionary<string, object> nestedDictionary)
{
if (nestedDictionary.TryGetValue(propertyName, out object dictionaryElement))
// First verify that the retrieved dictionary contains the component identifier { "__t": "c" }.
// If not, then the retrieved nested dictionary is actually a root-level property of type map.
if (nestedDictionary.TryGetValue(ConventionBasedConstants.ComponentIdentifierKey, out object componentIdentifierValue)
&& componentIdentifierValue.ToString() == ConventionBasedConstants.ComponentIdentifierValue)
{
// If the value is null, go ahead and return it.
if (dictionaryElement == null)
{
propertyValue = default;
return true;
}

// If the object is of type T or can be cast to type T, go ahead and return it.
if (dictionaryElement is T valueRef
|| NumericHelpers.TryCastNumericTo(dictionaryElement, out valueRef))
if (nestedDictionary.TryGetValue(propertyName, out object dictionaryElement))
{
propertyValue = valueRef;
return true;
// If the value associated with the key is null, then return true with the default value of the type <T> passed in.
if (dictionaryElement == null)
{
propertyValue = default;
return true;
}

// If the object is of type T or can be cast to type T, go ahead and return it.
if (dictionaryElement is T valueRef
|| NumericHelpers.TryCastNumericTo(dictionaryElement, out valueRef))
{
propertyValue = valueRef;
return true;
}
}
}
}
else
{
// If it's not, we need to try to convert it using the serializer.
Convention.PayloadSerializer.TryGetNestedObjectValue<T>(componentProperties, propertyName, out propertyValue);
return true;
// If the ClientPropertyCollection was constructed by the SDK (eg. when retrieving the client properties)
// then the componentProperties are retrieved as the json object that is defined in the PayloadConvention.
// The required property value then needs to be deserialized accordingly.
try
{
// First verify that the retrieved dictionary contains the component identifier { "__t": "c" }.
// If not, then the retrieved nested dictionary is actually a root-level property of type map.
if (Convention
.PayloadSerializer
.TryGetNestedObjectValue(componentProperties, ConventionBasedConstants.ComponentIdentifierKey, out string componentIdentifierValue)
&& componentIdentifierValue == ConventionBasedConstants.ComponentIdentifierValue)
{
// Since the value cannot be cast to <T> directly, we need to try to convert it using the serializer.
// If it can be successfully converted, go ahead and return it.
Convention.PayloadSerializer.TryGetNestedObjectValue<T>(componentProperties, propertyName, out propertyValue);
return true;
}
}
catch
{
// In case the value cannot be converted using the serializer,
// then return false with the default value of the type <T> passed in.
}
}
}

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32 changes: 23 additions & 9 deletions iothub/device/src/PayloadCollection.cs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -107,13 +107,11 @@ public bool Contains(string key)
/// <summary>
/// Gets the value of the object from the collection.
/// </summary>
/// <remarks>
/// This class is used for both sending and receiving properties for the device.
/// </remarks>
/// <typeparam name="T">The type to cast the object to.</typeparam>
/// <param name="key">The key of the property to get.</param>
/// <param name="value">The value of the object from the collection.</param>
/// <returns>True if the collection contains an element with the specified key; otherwise, it returns false.</returns>
/// <param name="value">When this method returns true, this contains the value of the object from the collection.
/// When this method returns false, this contains the default value of the type <c>T</c> passed in.</param>
/// <returns>True if a value of type <c>T</c> with the specified key was found; otherwise, it returns false.</returns>
public bool TryGetValue<T>(string key, out T value)
{
if (Logging.IsEnabled && Convention == null)
Expand All @@ -122,9 +120,16 @@ public bool TryGetValue<T>(string key, out T value)
$"TryGetValue will attempt to get the property value but may not behave as expected.", nameof(TryGetValue));
}

// If the key is null, empty or whitespace, then return false with the default value of the type <T> passed in.
if (string.IsNullOrWhiteSpace(key))
{
value = default;
return false;
}

if (Collection.ContainsKey(key))
{
// If the value is null, go ahead and return it.
// If the value associated with the key is null, then return true with the default value of the type <T> passed in.
if (Collection[key] == null)
{
value = default;
Expand All @@ -139,9 +144,18 @@ public bool TryGetValue<T>(string key, out T value)
return true;
}

// If it's not, we need to try to convert it using the serializer.
value = Convention.PayloadSerializer.ConvertFromObject<T>(Collection[key]);
return true;
try
{
// If the value cannot be cast to <T> directly, we need to try to convert it using the serializer.
// If it can be successfully converted, go ahead and return it.
value = Convention.PayloadSerializer.ConvertFromObject<T>(Collection[key]);
return true;
}
catch
{
// In case the value cannot be converted using the serializer,
// then return false with the default value of the type <T> passed in.
}
}

value = default;
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